Definition of V1
- The maximum speed in the take off at which the pilot must take the first action (eg apply brakes etc) to stop the aircraft within the ASDA, and
- The minimum speed in the take off, following the failure of the critical engine at Vef at which the pilot can continue the take off and achieve the required height above the take off surface within the distance available.
- V1 must be greater than or equal to Vmcg
- V1 must be less than or equal to Vr
- V1 must be less than or equal to Vmbe
- V1 = The speed on which from a balanced field takeoff it is possible to either reject the takeoff and stop within the available stopping distance or to continue after engine failure and clear a screen height of 35 feet at the end of the surface available. In effect V1 is a “go speed”.
Definition of Vr
- Rotate speed is never less than V1 or 1.05 Vmca
Definition of V2
- The airspeed at which the aircraft complies with those handling criteria associated with the climb after take off and the target speed to be attained at the 35ft screen height, assuming recognition of an engine failure at or after V1 and maintained to the point where acceleration to flap retraction speed is initiated.
- V2 must be greater than or equal to 1.2 Vs
- V2 must be greater than or equal to 1.1 Vmca
- V2 is the take-off safety speed or initial target climb speed. It is the speed to be attained at or before 35’ following an engine failure to ensure climb gradients are achieved and hence obstacles are cleared by the required margins.
Definition of Vmca
- The minimum airspeed at which, when sudden and complete failure of the critical engine occurs at that speed, it is possible to recover the airplane with that engine still inoperative and maintain it in straight flight at that speed, either with zero yaw or with an angle of bank not in excess of 5 degrees.
- Must be greater than or equal to 1.2 Vs (with undercarriage retracted and flaps in take off position).
Definition of Vmcg
- Is the minimum speed on the ground during the take off run, at which it is possible to recover control of the aircraft with the use of the primary aerodynamic controls and the take off can be continued safely, when the critcal engine suddenly becomes inoperative, with the remaining engines at take off thrust.
- VMCG is the minimum speed on the ground during the take off run, at which it is possible to recover control of the aircraft with the use of primary aerodynamic controls and the takeoff can be continued safely, when the critical engine suddenly becomes inoperative, with the remaining engines at takeoff thrust. Usually VMCG is higher than VMCA as cannot use 5° bank.
Definition of Va
- Design Manoeuvring Speed, the maximum speed at which application of full available rudder, aileron or elevator will not overstress the aircraft.
- VA is the design manoeuvring speed, the maximum speed at which application of full available rudder, aileron or elevator will not overstress the aircraft.
Performance Group A
- Capable of continuing a flight in IMC after failure of a critical engine at speed V1 and proceeding to a suitable aerodrome and landing.
- All multi-engine turbo-jet and all multi-engine turbo-prop with more than 9 seats or with MTOW > 5,700kg
Definition of runway
- Defined rectangular area for take off and landing run of aircraft.
Definition of stopway
- Clear area immediately beyond the runway and at least as wide, capable of supporting aircraft for braking.
Definition of clearway
- Clear area immediately beyond the runway over which aircraft may fly at a height of 35 ft. Can include stopway.
What is runway distance known as?
- TORA Take off run available
- Runway length excluding stopway
What is ASDA?
- Accelerate Stop Distance Available is the combined distance of runway and stop-way.
What is TODA?
- Take off distance available, is the runway and clearway. Clearway includes stopway.
What is A Balanced Field?
- Is when TODR = ASDR i.e. when the clearway is the same as the stopway.
How is ASDA calculated?
- Distance to accelerate to V1 - 1 second recognition - 2 second transition phase - distance to bring aircraft to stop. Engine failure occurs prior to V1, as your decision should have been made by V1.
What is the relationship between TORA and TODA?
- TORA, usable length of runway, it DOES NOT take into account of and clearway or stopway.
- TODA, usable length of runway PLUS any decleared certified clearway.
What is take off run required?
- Is the distance required to accelerate to V1, engine fail, continue to midway between Vlof and 35ft point.
- Or 115% of distance to reach to point midway between lift off and 35ft point (all engines), whichever is greater.
What is the take off distance required?
- The distance required to accelerate to V1, engine fail, continue climb to 35 ft.
- Or 115% of the distance to reach 35ft point (all engines), whichever is greater.
Vlof is limited by?
- Speed at actual lift off is limited by:
- Max tyre speed / Vmbe
State the climb requirements
- 1st segment, 35ft to gear retracted (+ve ROC)
- 2nd segment, end of 1st segment to 400ft or higher flap retract height, at V2 (2.4% climb gradient required)
- 3rd segment, end of second segment, level acceleration to final climb speed (1.2% climb gradient capability required)
- 4th segment, end of 3rd segment to 1500ft, at or greater than 1.25 Vs (1.2% min climb gradient required).
The net take off flight path is deemed to end when..
- the aircraft passes 1500ft
What is the use of the extended second segment climb?
- Rather than retract flap in the 3rd segment, the flaps are kept down, and on reaching the 5 min take off thrust time, the power is set to MCT. After which the flaps are then retracted, this allows for improved climb gradient but is only to be used for obstacles within the 2nd and 3rd segement. The aircraft must be clean by the 400ft point if obstacle clearance is required in the final segment.
Reduced thrust take offs are dependant on...
- Field length
- Take off flight path (obstacles)
- Engine inop climb gradients
- Aircraft take off weight
What are the disadvantages of a reduced thrust take off?
- Longer climb time
- Higher fuel burn
What conditions should reduced thrust take off not be used?
- Standing water (ice/slush/snow)
- Mixed engine configuration
- Any non-standard take off
What is the reduced screen height for a wet take off?
State the critical engine on a jet during take off?
- Nil in head wind
- The most upwind engine in crosswind due to increased yaw if engine fails (weather cocking).
- In the cruise the outboard engines of a 4 engine aircraft are critical.
- Beech 1900d Left engine
What effect does a balanced field have on take off performance?
- A balanced field means that it is critical that an abort is carried out immediately on engine failure recognition.
- Also that the take off on one engine could be marginal if continued as a balance field is a take off right on performance limits for the given aircraft weight - not favourable.
Definition of second segment of take off path?
- From gear retraction to level acceleration altitude, which is normally a minimum of 400 ft above take off surface. In this segment the gear is retracted, the flaps are in take off position and the aircraft is set in take off power. The speed is equal to V2 (initial climb out speed) and the required minimum gross gradient of climb, in a two engined aircraft, is 2.4%. The net flight path gradient is the gross flight path gradient reduced by 0.8%, i.e 1.6%.
- Conditions are
- Landing gear is retracted
- Flaps are still in take off position
- Speed is V2
- The minimum gross climb gradient in a twin engined aircraft is 2.4%
- The minimum net climb gradient in a twin engined aircraft is 1.6% and
- take off power is still set.
Definition if ISA
- 1013.25 hPa (29.92"hg)
- 15 degrees Celcius
- Lapse rate is 1.98 degrees celcius per 1000' up to 36,090' then -56.5 degrees celcius
- Density is 1.225 kg/m3
Aircraft maintains a constant IAS in climb, what happens to TAS & LSS & Mach?
- Constant IAS
- TAS will increase
- LSS will decrease
- Mach will increase
How does temperature affect the speed of sound?
- The speed of sound is directly proportional to the square root of the absolute temperature (the speed of sound will increase with an increase in temperature)
- LSS =38.94^K
- At sea level ISA LSS=661kts
- At 35,000' ISA LSS=575kts
Airspeed in a climb at a constant TAS/IAS/Mach No. What do each other do?
- Constant IAS = Both TAS & Mach No INCREASE
- Constant Mach No = Both IAS & TAS DECREASE
- Constant TAS = Mach No INCREASE, IAS DECREASE
Cruise Mach No is more limiting when?
- In warm temperatures
- The higher the aircraft flies
- *When Mach number is reduced (high altitudes) and when TAS is reduced (warm temperatures)*
What happens to the speed of sound with altitude / temperature?
- LSS reduces with altitude and with cooling temperatures
Formula for True Altitude?
- TA = Actual temp (K) x Indicated altitude
- . ISA temperature (K)
True altitude is your actual altitude above mean sea level, no errors.
Absolute altitude is your height above ground.
Explain airspeed errors?
- IAS - Position error - CAS - Compressibility error - EAS - Density error - TAS
What errors does a Mach meter NOT suffer from?
- Density error and compressibility error
The two capsules in a Mach meter are what?
- Altitude calibration
- Free stream Mach Number - airflow unaffected by the aircraft
- Local Mach number - is the speed of air relative to the local speed of sound measured at a point on the aircraft.
- The lowest free stream Mach number at which Mach 1 is reached on any part of the aircraft.
- MCRIT is the critical Mach number. This is the speed at which the airflow over certain parts of the airframe (most likely the point of maximum camber of the aerofoil) reaches M1.0. MCRIT is increased through slimness and through the use of sweepback.
How does weight affect Mcrit?
An increase in weight will reduce Mcrit
Drag divergence Mach number is...
- The increase in drag associated with compressibility effect (110-115% of Mcrit)
What happens to the centre of pressure (CP) leading up to super sonic flight?
- The CP is well forward (below Mcrit)
- The CP moves rearward (in excess of Mcrit)
- The CP moves forward Mcrit - Mfs > M1
- The CP gradually moves further rearward as speed increases further
Wave drag is...
- The separation of the airflow behind the shock wave
A shock stall is the result of...
- The boundary layer behind the shock wave becoming turbulent and separating, spilling rearwards and striking the tailplane, creating buffet and rearwards CP movement. Rear movement of the CP causes nose pitch down.
Wing design for high speed flight takes into consideration..
- Minimal camber to delay shock waves
- Low thichness chord ratio
The primary purpose of sweep back is to..
- Increase the value of the critical mach number
How does sweep back work?
- By sweeping the wing the freestream air that travels along the effective chord is less, therefore less acceleration is achieved resulting in a lower speed over the wing and a higher achievable aircraft speed before Mcrit is reached.
Advantages of a swept wing?
- Mcrit increased
- Higher economical cruise speed (delays onset of compressibility effects)
- Increased lateral stability (roll)
- 'Softens' the onset of the force divergence number
Disadvantages of sweepback?
- Lower CL max (flatter curve giving higher stall speed)
- Extensive use of high lift devices
- High drag at high AOA (CL max obtained at high AoA, overcome by slots & flaps)
- Use of vertex generators, wing fences to reduce wingtip 'pooling'
- Prone to wing tip stalling (tips are aft part of the wing and separation point is closer to the leading edge.)
- Taper adds to tip stalling but reduces induced drag.
- T tail makes stalling worse as it provides little or no buffet warning (use stick shaker)
- Sweepback increases drag at low speeds as it gives more spanwise flow than high speeds (due to time).
A swept wing aircraft pitches up or down at a stall?
- A nose pitch up results from the wing tips stalling first moving the CP inwards and forwards (wash out is used to try and prevent tip stalls)
Wash out is...
- A decrease in incidence from root to tip – to prevent wing tip stall
What devices are used to prevent wing tip stall (spanwise flow)?
- Wing fence
- Saw tooth leading edge (generate a vortex to re-energise the flow)
- Vortex generators (re-energise the flow)
What happens to the center of pressure in a stall in a swept wing aircraft?
- Tips will stall first so CP moves inward and forwards & nose tends to pitch up
During a turn what happens to the CP of a swept wing aircraft?
As the wing gets higher in a turn the outer portion become higher than the inner portion which creates its own form of washout resulting in a lower AOA and causing the CP to move inwards and pitch the nose upwards.
- Downgoing wing has a relative airflow more from below, upgoing wing has a relative airflow more from above.
- The upward inclination of the wing to the lateral axis to provide lateral (roll) stability
- Negative dihedral – usually with high mounted swept wings to combat dynamic instability (dutch roll)
- This is a design function to ‘blend’ areas where wings, tail, join the fuselage to minimise the increasing and decreasing cross section, minimizing the amount of drag formed by shockwaves. The area of cross section should increase gradually to a maximum, then decrease gradually. Giving more streamline shape. Max cross-section area should be approx half-way.
Formula for Aspect Ratio is...
- AR = Span (width) / Chord (length)
High Aspect ratio (subsonic speeds) gives...
- Better lift
- Better lift/drag ratio
- Less induced drag due reduced wing tip vortices
What is Mach tuck?
- Is when the aircraft is accelerated through the transonic range causing the CP to move rearwards and increasing the lift generated by the tail plane due to modified airflow from the wing causing a nose pitch down.
What happens if Mach tuck is not corrected?
- The nose pitch down causes further speed increase which causes further movement rearwards of the CP which causes further nose pitch down…..etc
Oscillatory instability is...
- A combined yawing and rolling movement
What is dutch roll and what causes it?
- It is oscillatory instability when the rolling motion is predominant and,
- It is a yaw to the left or right which makes the outside wing speed up producing more lift resulting in a roll, after which because of the greater exposed area of the faster wing it has a higher drag component therefore causes a yaw in the opposite direction, resulting in a roll in the direction of the yaw.
- A yaw damper is a gyro system sensitive to changes in yaw which feeds a signal into the rudder which then applies rudder to oppose the yaw. With this device, a Dutch roll will not develop because the yaw which triggers it all off is not allowed to develop. It applies the rudder in the correct direction and in the correct amount, thus preventing the slip starting or building up and stopping all rolling tendency Apart from the swept wing, the basic cause of Dutch rolling tendency is lack of effective fin and rudder area.
What is a stabilising device to prevent dutch roll?
What is snaking?
- Oscillatory instability when the yawing motion is predominant
Oscillatory instability is worse when...
- At high altitudes
- On sweepback aircraft at low IAS
High altitude = High angle of attack = High dihedral effect = High chance of dutch roll.
Approach at slow speeds = High angle of attack = High dihedral effect = High chance of dutch roll.
The aircrafts aerodynamic ceiling is...
- The point at which the high airspeed mach buffet and low speed stall buffet merge, called coffin corner.
The manoeuvre envelope must be...
- At an altitude and airspeed sufficient to avoid stalling and slow enough to avoid structural damage
Gliding angle depends on...
- Ratio of lift to drag ratio – greater weight does not effect gliding angle or range, does effect speed.
Rate of vertical descent depends on...
- Angle of glide and airspeed
Aircraft in constant descent at 300kts, how does weight affect glide angle.
- The heavier the aircraft, the earlier descent must commence. So the more shallow the glide angle.
- Conversely, the lighter the aircraft, the steeper the descent glide angle, for the same speed as the heavier aircraft.
Define rolling, pitching and yawing movement. About what axis, called what stability?
- Rolling is about longitudinal axis and is lateral stability
- Pitching is about lateral axis and is longitudinal stability
- Yawing is about normal axis and is directional stability
What is the resultant of using ailerons for turning / rolling, and how is it corrected?
- Adverse aileron yaw which is caused by the lowering of one aileron (down going aileron, up-going wing)
- Lowered aileron causes additional drag which produces a yawing moment in the opposite direction. By increasing the angle of attack too much causing more drag and by aileron pushing into airflow.
- Corrected by use of spoilers and differential or frise ailerons. Or slot-cum-aileron control (Kermode p302)
What is the difference between differential and frise ailerons?
- Differential ailerons: Up going aileron moves through large rangle to increase drag
- Frise ailerons: Up going aileron projects below as well to cause excessive drag
Aileron size is limited by...
The effect of wing twist from operating ailerons at height speed is...
- It will minimise the effect of the ailerons / reverse the effect all together. Turning at high speeds can increase lifting forces on the upgoing wing so much that it twists the wing and reduces the effective AoA. Use inboard ailerons or spoilers at high speeds.
How do ailerons prevent wing twist at high speeds?
- They are locked out to prevent wing twisting, inboard ailerons are employed to provide roll as well as spoilers.
How do spoilers produce roll?
- The spoilers are raised on the down going wing reducing the lift on that wing
What are the function of spoilers?
- Lift dumping in flight – increase the rate of descent
- Speed brakes in flight – to quickly decrease speed in flight
- Ground spoilers to destroy lift – to achieve shorter landing distances
- Assist lateral (roll) control - allows smaller aileron size, avoids aileron reversal
- Direct lift control
What is direct lift control?
- Use of aerodynamic surfaces (spoilers) to provide control of rate of descent without need to change body angle on approach
What are differential spoilers?
- They provide roll control when flight spoilers are in use and aileron input is given
What is the limitation of spoilers?
- At high speed they can blow back
What is the reason for using a variable incidence tail plane?
- To counteract large trim changes through use of fuel and large speed changes allowing the elevator to remain fully effective under all conditions of longitudinal trim
- Less drag at high speed
- Provides control when a shockwave forms on the tail plane
Power assisted controls provide what?
- Pilot force which is assisted by power units which in turn provides “Feel"
- Provide all the force necessary to operate a control surface, control column feel is provided artificially
What is Q feel?
- An artificial method of providing the pilot with control column loading using either springs or hydraulics which provide variable loading proportional to airspeed
Extending flaps increases what?
- Wing camber
- Wing area and CL
Slotted flaps allow...
- The airflow to be re-energised avoiding separation
Large aircraft are usually fitted with what type of flap?
- Slotted fowler (moves down and rearward)
When does aileron droop occur?
- When flaps are extended (usually the inboard ailerons)
A Krueger flap does what?
- Extends forward of the leading edge providing an increase camber
Leading edges slats extend...
- Outwards providing a slot to delay boundary layer separation
An aft / forward C of G has what effect on the stall speed?
- Aft decreases the stall speed and forward increases the stall speed
What are the purposes of vortex generators?
- To re-energise the boundary layer & delay separation or air from wing
What is hydroplaning and what does it depend on?
- When a tyre is lifted clear of the runway due to a build up of fluid pressure beneath the tyre
- Tyre pressure
- Runway surface
- Tread depth
- Tyre speed
- Water depth
- Runway grooving
What is the formula for the Hydroplaning Speed?
Rotating and Non-rotating.
- Rotating = 9.0 x square root of tyre pressure
- Non-Rotating = 7.7 x square root of tyre pressure
- Beech Nose wheel 60psi, Main gear 97psi +/- 5psi
- = 88kts rotating, 75kts non-rotating
When are reduced thrust take off's used?
- There is a long runway available
- MTOW is low
What are the 2 methods for reduced take offs?
Fixed derate (i.e 10%-20%) - For a given ambient condition, the thrust reduction achieved by selecting another certified takeoff rating that is lower than the maximum takeoff rating.
Assumed temperature - Based on a certified takeoff rating and ambient condition, the thrust reduction achieved by selecting the rated thrust for a temperature that is higher than the outside air temperature.
Using an assumed temperature reduced thrust take off, what speed corrections are there?
- V1 is reduced to allow for slower acceleration but other speeds are the same for the actual TOW
Factors that affect the engine thrust...
- Mass airflow increases...Thrust increases
- Temp increases...Thrust decreases
- Humidity increases...Thrust decreases
- Altitude increases..Pressure decreases...Thrust decreases
What is ram effect?
As the aircraft increases speed the increase in density and mass flow through the engine results in an increase in thrust
An increase in engine RPM results in...
- Higher mass air flow
- SFC decreases
- Higher temps
- Thrust output increases
Two ways of measuring thrust are:
- EPR (the ratio of inlet pressure and turbine exit pressure)
- N1 (low pressure rotor speed)
Engine bleed air has what effect:
- EPR decreases (engine pressure ratio)
- EGT increases
- Thrust decreases
What is a compressor stall / surge?
A reverse flow of air through the engine caused by unstable air
Reverse thrust is most efficient at...
Documents required for international flight?
- C of A
- Aircraft F/Manual
- Aircraft Registration
- Flight Crew Licences
- Valid Maint. Release
- Load Sheet
- Flight records
- List of Crew & Passengers
- Cargo bills of lading and manifests
- List of disposable stores and spare parts
- Route Guide
What separation is provided by ATC between IFR & VFR traffic in Class “C” & “D” airspace?
- “C” IFR from IFR, VFR & SVFR
- “D” IFR from IFR, SVFR. IFR not from VFR, they are given traffic information.
- “E” IFR from IFR. IFR and VFR get traffic information. Shall not include control zones.
When does the Runway Centreline Lights (RCLL) turn red?
- White to a point 914m from runway end.
- Alternate white & red between 914m & 300m.
- Red between 300m & the runway end.
Definition of CAVOK?
- The term CAVOK is an acceptable contraction (meaning Ceiling and Visibility OK) for international use. It indicates that:
- No clouds exist below 5,000 feet or below the highest minimum sector altitude, whichever is greater, and no cumulonimbus are present.
- Visibility is 10 kilometres or more and,
- No precipitation, thunderstorms, sandstorm, dust storm, shallow fog, or low drifting dust, sand or snow is occurring.
What are the classes of dangerous goods?
- Class 1 Explosives Every
- Class 2 Gasses Girl
- Class 3 Flammable Liquids Likes
- Class 4 Flammable Solids Sex
- Class 5 Oxidising Substances Orally
- Class 6 Poisonous / Infectious substances Plus
- Class 7 Radioactive substances Receiving
- Class 8 Corrosive agents Cum
- Class 9 Those that don’t fit above, eg magnetic materials
If the static port blocks during the climb, what will the altimeter read?
- Whatever the reading was at the time of the blockage.
What is the definition of Part 121?
- Pax configuration of more than 30 seats (excluding crew member seats)
- Payload capacity of more than 3410 Kg
What is the purpose of Part 119?
- To prescribe the certification requirements for operators to perform Air Operations and the operating requirements for the continuation of this certification. Air Operations include Air Transport Operations (ATO) and Commercial Transport Operations (CTO).
What is the purpose of Part 121?
- To prescribe the operating requirements for air operations of aeroplanes that have a passenger seating configuration of more than 30 seats, excluding any required crew member seat, or a payload capacity of more than 3410 kg, carried out by the holder of an Airline Air Operator Certificate issued under Part 119 of the Rules.
What is the purpose of Part 61?
- Prescribes the requirements to hold pilot licences and ratings; the prerequisites for those qualifications; and their privileges and limitations.
What is the purpose of Part 91?
- Part 91 is an important rule as it forms the basis of general operating and flight rules for the New Zealand aviation environment. The requirements ensure that the safe operation of aircraft is possible with the minimum endangerment to persons and property.
What is the critical engine on a propeller aircraft?
- On a propeller aircraft with conventionally rotating propellers, the critical engine is the left outboard engine, conversely with propellers rotating anti-clockwise, the outboard right engine would be critical. Counta/contra-rotating propellers do not have a critical engine.
- With conventionally rotating propellers, the down-going blade on each engine has a greater angle of attack producing more lift (thrust) thus offsetting the thrust line on each engine to the right. The right engine (on conventionally rotating propellers) has a greater arm to the C of G causing greater yaw, making the left engine critical.
How does crosswind affect the critical engine?
- On a propeller driven aircraft, a crosswind from the opposite side to the critical engine will assist the situation because the yaw required to offset that which is produced by the failure of the critical engine will be assisted by the effect of the crosswind (weathercocking).
- The reverse situation will make matters worse. Crosswind from the same side as the critical engine will require even more demand from the rudder. The yaw produced by the failure of the critical engine will be compounded by the effect of the aircraft weathercocking.
What are the approach speeds for Cat B?
- CAT BVat (1.3Vs) 91 - 120
- Initial App...120 - 180 (140 Reversal turn)
- Final App...75 - 130
- 45/180 degree turn...1 min
What is ETP and what is the formula?
- Equi time point – a point enroute where it will take the same time to go back as it will to carry on
- Dist to ETP = Distance x GS home G/S onward + G/S home
- With a tailwind out ETP will move closer to departure.
- ETP moves into wind
What is PNR and what is the formula?
- Point of no return – a point which is based on fuel (endurance) at which you have the fuel to return if req’d
- PNR Formula
- Time to PNR (min.s) =
- Endurance (min.s) x G/S home
- G/S out + G/S home
Dist to PNR =
- Endurance (hrs(decimals)) x G/S out x G/S home G/S out + G/S home
What is the formula for Equivalent Still Air Distance?
The distance the aircraft has flown through the air.
What is the formula for Gross fuel flow?
- GFF = Fuel Flow (kg/hr)
- G/S (nm/hr) = kg/gnm
What is endurance?
- With endurance we need to fly as long as possible for a given amount of fuel. To use the least amount of fuel we need to use the least amount of thrust therefore we must fly at the speed for MIN DRAG. This is found at the bottom of the TOTAL DRAG vs IAS curve.
- Since the thrust, and hence the consumption, should be the same at the same indicated speed at any height, it should not matter at what height we fly for endurance. Actually, when engine efficiency is taken into account, there are advantages in flying high (engine operating at design speeds and also the thermal efficiency, compressor efficiency, and the pressure ratio is better at higher altitudes).
- Fuel Consumption with increase in Alt remains Constant, However in practise fuel consumption decreases with altitude.
- In summary, for Endurance fly at speed for min drag as high as possible.
For maximum range we need to cover the maximum distance for a given amount of fuel. If we look at the TOTAL DRAG vs IAS curve once again then it can be seen that a very large increase in IAS can be achieved with a comparably small increase in total drag by drawing a line at a tangent to the curve. This is the speed for Maximum Range.
At this speed it is the least amount of power for the a/c to achieve the highest TAS this also equates to min drag and max lift/drag ratio.
The effect, on range, of an increase in weight requires in increase in speed for a constant angle of attack.
- Increase in headwind results increase in mach no. Aircraft will then be subjected to the headwind for a shorter period of time.
If you were loading an airplane to obtain max range, would you load it with a forward or aft CoG?
- It would be best to load it with an aft C of G as this would require an upward force from the tailplane (or less of a downward force required from the tailplane) which acts in the same direction as lift and hence opposes some of the aircraft’s weight. Less lift from the mainplane means less drag therefore less thrust is required, less thrust means reduced fuel flow and hence more range can be obtained for the amount of fuel on board.
Compare speed for Range Vs Endurance?
Speed for max endurance will always be lower than speed for max range.
Max range is greatest distance covered for the amount of fuel used.
- SAR = TAS / GFC (gross fuel consumption)
- Tangent to the power req curve. Best range TAS INCREASES with altitude not IAS. Reduce weight to increase range.
- Max endurance is to remain in the air for the greatest amount of time for least amount of fuel. Min drag speed.
- Best at SL (less power) for piston engine. High for turbines. Increase in weight, reduces endurance.
What sort of C of G changes occur on long flights?
- For a swept wing aircraft, as fuel is burnt off, the C of G moves forward. A consequence of a forward C of G is that the tailplane must then produce a compensating downwards balancing force which effectively increases the weight to be supported by the wing resulting in a higher stall speed at a constant weight.
- An aft C of G is the best for fuel consumption as there is less downward push applied to the tailplane, effectively reducing weight, resulting in a lower stall speed.
- A forward C of G is the most stable-stability of the aircraft is increased and the static and manoeuvre margins are large.
How does cruise speed vary with fuel burn?
- Cruise speed reduces with gross weight due to fuel burn – less weight requires less lift resulting in less drag, therefore thrust can be reduced.
What happens to SFC as altitude is gained?
What effect happens if the aircraft is flown past the optimum flight level?
SFC increases as excessive drag results from an increased AoA which is required to create enough lift to support the aircraft.
- (The optimum altitude occurs at the optimum angle of attack for least thrust greatest TAS)
Optimum altitude is a function of...
Does temperature affect optimum flight level?
- No as it has an equal effect on fuel flow and TAS
Specific air range formula is...
- SAR = TAS GFC (gross fuel comsumption)
Long range cruise is...
- Flight at an optimum flight level, the airspeed is slightly higher than that at max range cruise as it is proportional to A/C weight. The range is reduced by 1 – 2 % of the max range cruise. For 'Max Range Cruise' cost index is zero, otherwise for a slightly higher fuel burn the long range cruise gives faster speed and better stability in average conditions.
How does stall speed vary with C of G?
- A forward C of G increases stall speed.
- An aft C of G decreases stall speed
Factors affecting the stall speed?
How does VMCA vary with C of G?
- As the C of G moves forward, the arm to the rudder increases, increasing its effectiveness. The opposite occurs as the C of G moves rearward.
- Therefore: A forward C of G decreases Vmca,
- and an aft C of G increases Vmca
What is the function of an Inverter?
What is the function of a Rectifier?
What do CSD's do (Constant Speed Drives)..?
- A CSD runs off the accessory case and drives the AC generator at a constant RPM regardless of engine RPM. CSDs ensure that all generators are producing acceptable outputs of constant frequency, voltage, and phase, and allows each generator to be paralleled and to share the aircraft’s electrical load.
What is RVSM?
Reduced Vertical Separation Minimum.
In the late 1950s it was recognised that, as a result of the reduction in accuracy of the pressure-sensing capability of barometric altimeters with increasing altitude, there was a need above FL290 to increase the prescribed vertical separation of 1000ft.
In 1960, an increased Vertical Separation Minimum (VSM) of 2000ft was established for aircraft operating above FL290 except where, on the basis of regional air navigational agreement, a lower flight level was prescribed for the increased VSM. FL290 was chosen mainly as a result of the operational ceiling of aircraft at that time.
In the mid-1970s, a series of world fuel shortages and the resultant rapid escalation of fuel costs, allied to the growing demand for a more efficient utilisation of the available airspace, emphasised the necessity for a detailed appraisal of the proposal to reduce VSM above FL290.
- The review agreed that 1000ft VSM (RVSM) was technically feasible and found that it was necessary to establish:
- Airworthiness performance requirements embodied in a comprehensive minimum aircraft performance specification (MASPS) for all aircraft utilising the reduced separation;
New operational procedures; and
A comprehensive means of monitoring the safe operation of the system.
Up to FL410 inclusive.
Over time, air data computers (ADCs) combined with altimeters have become more accurate and autopilots more adept at maintaining a set level
Name the 5 main modes of GPWS
- 1-Excessive rate of descent SINK RATE
- 2-Excessive terrain closure TERRAIN PULL UP
- 3-Excessive altitude loss after take off DON'T SINK
- 4-Aircraft too low without gear or flap (shallow flight path) TOO LOW GEAR/TERRAIN/FLAP
- 5-ILS deviation (1.3 dots below glide-slope) GLIDESLOPE6-Advisory callouts
What are the inputs to GPWS?
- Radio altimeter
- ILS receiver
- Barometric pressure sensing
- Flap & gear position
What is the operating envelope of GPWS?
- 2450ft AGL to 30ft AGL (radio altimeter)
How does EGPWS (TAWS) operate?
- From a world surface database input & GPS it can calculate which terrain is conflicting with the aircraft and warn the pilots (forward looking)
What is TAWS?
- Terrain Awareness and Warning System will provide increased vertical situational awareness.
- They will also provide increased warning durations following system detection of terrain threats.
- Perhaps the most important result though is the fact that flight crews will be given.
- Continuous terrain display so that they would have perceived these terrain threats and responded to them before TAWS was required to generate warnings.
- Now called GPWS.
How does TCAS interrogates intruder aircraft, and what are the symbols?
- TCAS uses transponder signals from other aircraft to determine relative positions.
- Surveillance target - Open white diamond (nearby)
- Proximity target - Solid cyan (blue) diamond (within 1200 ft + 6 miles)
- Traffic advisory - Solid yellow circle (within 20 - 48sec’s)
- Resolution advisory - Solid red square (Within 15 - 35 sec’s -Avoidance
With TCAS when given a traffic advisory what would the pilots display indicate to him?
- A relative indication of a solid amber circle / the aircraft’s altitude / if it is climbing or descending (an arrow) and an aural “TRAFFIC TRAFFIC’
What is GPS, how does it work, and how many satellites are required?
- The Global Positioning System is a satellite-based radio navigation system which can provide users with position and time information of tremendous accuracy, anywhere on the earth, 24 hrs a day, and in all weather.
- Position in space is determined by measuring dist from a group of satellites in space, much like a DME fix but in 3 dimensions not 2.
- 4 minimum
What is differential GPS?
- Using ground based receivers at a known location to calculate error in the satellite data they then send other receivers (aircraft) an error correction message. Which in turncorrect themselves, computing a more ‘relative position between an aircraft receiver and a ground based receiver for them to track to.
Multi channel receivers are able to do what?
- Assign and lock onto individual satellites per channel enabling them to track and compute the most accurate position using the best satellites. Reducing the GDOP effect
What is GDOP?
- Geometry dilution of precision – the angle of the satellites relative to the aircraft, larger angles provide better accuracy of position and distance.
What is ADS?
- ADS is Automatic dependant surveillance – the ability to track aircraft using GPS position information which is automatically fed to ATC via the aircraft avionics. This will assist in reduced separation, least fuel tracks,
- ADS communication will also effectively relieve the need for voice communication.
Future Air Navigation System – Implementation of satellite technology for improved communication and navigation tracking surveillance.
It is an avionics system which provides direct data link communication between the pilot and the air traffic controller. The communications include air traffic control clearances, pilot requests and position reporting.
- ETOPS stands for Extended Range Twin Engine Operations and is the term used to govern regulations and procedures pertinent to twin engine commercial aircraft operating on extended global or domestic routes with poor off track alternates. The basic premise regarding this topic is related to the concept of redundancy and failures of the powerplant,/hull. The basis of ETOPS is the improved engine reliability shown by new age aircraft.
- The rules state that any aircraft with two engines must be capable of flying to an adequate airport where it can land safely within 90 minutes at normal cruise speed or 60 minutes at single engine cruise speed (in still air conditions). If the aircraft can not comply with the above regulation – it is then required to become an ETOPS rated aircraft.
- With an ETOPS rating, this rule is extended up to 90mins, 120mins, 138mins and 180mins.
- Individual aircraft must be specifically authorised. As new aircraft are introduced to the fleet a proving period is implemented at 120 min before a higher classification is considered.
- Air New Zealand currently operates B737 on 120min ETOPs, B767 on 180 min ETOPs and B777 on 240 min ETOPS. However when suitable alternates exist it for 120 min ETOPS it may be advantageous to operate to this criteria as opposed to 180 min. These advantages are in the area of MEL dispatch and minimum fuel reserves to be carried.
- The ETOPS times stipulated simply determine the single engine time in still air from which an aircraft must remain from a suitable alternate.
Explain Great Circle.
- A circle drawn on the face of the earth whose radius is the earth. Its plane passes through the centre of the earth. It is the shortest distance between two places.
Explain Small Circle.
- Any circle drawn on the earth whose radius is not the earth. Its plane does not pass through the centre of the earth.
Explain Rhumb line.
- A line drawn on the centre of the earth which cuts each meridian at the same angle.
Explain Parallel's of Latitude.
- Small circles joining points of equal latitude – except equator, which is a great circle
- All are rhumb lines
- Lie east to west
Explain Meridian's of Longitude.
- Semi-great circles passing thru the poles.
What is Prime Meridian?
- A semi-greatcircle passing through the poles and also Greenwich. Known as the Greenwich meridian. It defines a longitude of zero degrees.
- 0000UTC is said to exist when the sun is directly over head the anti meridian (180)
What is an Isogonal?
- Line joining points of equal variation
Define Nautical Mile.
- Distance on the surface of the earth which subtends an angle of one minute of arc at the centre of the earth
- 6080 ft
- One degree of change of latitude along a meridian represents a distance of 60nm (60min of arc)
What is departure formula?
- Necessary due to the fact that 1 degree of longitude is only equal to 60nm at the equator. Any deviation from the equator needs reference to the departure formula.
- Distance (nm) = change of long(in mins of arc) x cos lat
Explain Earth Convergency.
- The angle of inclination between two meridians at any given latitude
- Earth convergency = change in long x sin mean lat
What is the rotation of Earth?
- 900kts at equator, or
- 900 x Cos Lat = speed at a given latitude
Explain Mercator Projection?
- Cylindrical projection
- All meridians appear as straight lines with parallel spacing
- All parallels are straight lines with the distance between them increasing with increase in latitude
- Poles are unable to be projected
- Lat and long intersect at right angles
- A Rhumb line will appear as a straight line
- A great circle will appear as a curved line concave to the equator
Explain Lambert Projection
- This utilises a conical projection with the apex of the cone directly above the pole
- Meridians appear as straight lines converging towards the pole
- Parallels appear as straight lines with the distance between them being constant
- Lats and Longs intersect at right angles
- Rumb lines appear as curved lines concave to the nearest pole
- Great circles appear as straight lines (in fact the are very slightly curved toward the parallel of origin.
What is Conversion Angle?
- This is the angle between the great circle track between two points and the rhumb line track between two points. It is equal to half earth convergency.
- Conversion angle = 0.5 change in long x sin mean lat
- All chart used for nav must have these two qualities.
- The scale on the chart must be correct to the scale nearby (equal scale expansion)
- Parallels and meridians must cross at right angles.
What is Time to Arc?
- 1° of arc = 4 min
- 15’ of arc = 1 min
- 1’ of arc = 4 sec.
- Converting Longitude by using West=Best, East=Least
- degrees x 4 = min (+ 1 min for each 15'). Add this to LMT to get UTC.
How do you calculate Pressure Altitude?
- Difference in QNH x 30
- QNH Hi - Lo
- QNH Lo - Hi
- + Elevation
- OR Set 1013 (29.92) on Altimeter
How do you calculate Density Altitude?
- Density altitude in feet = pressure altitude in feet + (120 x (OAT - ISA_temperature))
Formula for LSS?
What is the LSS at sea level in ISA conditions?
- LSS = 38.94 x square root of Temp (Kelvin)
- LSS at SL on ISA day is: 660.83kt
Cimbing at a constant Mach number, IAS and EAS will...
- Decrease up to 36,000 ft when it remains constant
At what speed does compressibility have little effect?
Whay is too much taper bad?
- It leads to tip stalling whilst twist (washout) reduces this
How does glove fairing at the wing root affect Mcr?
- It increases it by delaying the formation of the shock wave and decreases drag in the cruise speed range.
What are vortex generators used for?
- Increase speeds
- Improve initial buffet boundaries
- Improve aircraft controllability
- Reduce vibrations from boundary layer separation
Wing fences are for...
- reducing span wise flow
How is the speed range between low speed buffet and high speed mach buffet change?
- It reduces with altitude and will reduce with weight as the stall speeds increase even though Vmo/Mmo are unchanged with weight.
- Buffet at high altitude below Mmo may occur with either gusts or manoeuvres.
Why should you use a Mach Meter rather than an ASI above FL270?
- As an aircraft in transonic flight approaches the speed of sound, it first reaches its critical mach number, where air flowing over low-pressure areas of its surface locally reaches the speed of sound, forming shock waves. The indicated airspeed for this condition changes with ambient pressure, which in turn changes with altitude. Therefore, indicated airspeed is not entirely adequate to warn the pilot of the impending problems
Formula for Total Air Temperature TAT?
HSI stands for...
- Horizontal Situation Indicators
ADI stands for...
- Attitude Direction Indicator
INS stands for...
- Inertial Navigation System
ADF stands for...
- Automatic Direction Finding Equipment
RMI stands for...
- Radio Magnetic Indicator
VOR stands for...
- VHF Omnidirectional Range
- Each dot is 5 degrees, full dflection 10 degrees
DME stands for...
- Distance Measuring Equipment
ILS stands for...
- Instrument Landing System
FMS stands for...
- Flight Management Systems
How many flight do Air New Zealand operate each week, how many destination and what is their biggest market?
- 4000 flights per week
- 27 destinations international and 27 Domestic
- Australia is the biggest market at nearly 170 flight per week.
Name some of Air New Zealands innovations?
- The worlds first in-flight international Airline Concierge service
- Large investment in in-flight entertainment
- Domestic airport self check-in
What is Air New Zealands goal?
- To be the worlds most environmentally sustainable airline. They have plans in place to reduce and offset aircraft emissions.
What are the 5 qualities to be found in all Air New Zealanders?
- Commitment to excellence
- Commitment to customer service
- Commitment to safety
- Commitment to each other
- Commitment to promoting New Zealand
What are our 5 guiding principles?
- We will be the customers airline of choice when travelling to, from and within New Zealand.
- We will build competitive advantage in all of our businesses through the creativity and innovation of our people.
- We will champion and promote New Zealand and it's people, culture and business at home and overseas.
- We will work together as a great team committed to the growth and vitality of our company and New Zealand.
- Our workplaces will be fun, energising and where everyone can make a difference.
What are the 5 attitudes found in Air New Zealanders?
- Hard working
- Can do
- An uncompromising approach
What is the company's vision?
- We will strive to be number one in every market we serve by creating a workplace where teams are committed to our customers in a distinctively New Zealand way, resulting in superior industry returns.
How many aircraft?
- B747-400 2
- B777-300ER 5
- B777-200ER 8
- B787 10 on order
- B767-300ER 5
- A320 Shorthaul 13
- A320 Domestic 4 with 10 on order
- B737-300 13
- ATR72-500 11
- ATR72-600 7 on order
- Q300 23
- B190 18
How many seats and what cruising speed for:
- B777-300ER has 332, 910 kph
- B777-200ER has 304, 910 kph.
- B767-300ER has 234, 870 kph
When flying from AKL to Perth on a great circle, what happens to heading? Does it slowly increase or decrease?
- Heading will increase as great Circle is concave to equator on Mercator chart
When flying from AKL to Perth on a great circle, is it a straight or curved line on a Lamberts chart?
- Great circles are straight lines on Lamberts charts (in fact very slightly curved towards parallel of origin)
At what altitude does temperature remain constant?
- 36,090 ft at -56.5 degrees celcius
When flying EAST, are days longer or shorter?
- Shorter as earth is rotating towards East
Which part of a swept wing stalls first?
- A raw swept wing will stall at the tips first. The total airflow over the swept wing includes a span wise vector. The flow of air outwards along the wing causes the boundary layer on a swept wing to drift outwards towards the tips resulting in an undesirably thick boundary layer in the region of the tips. The retardation of the air by the boundary layer is one of the major causes of the stall.
- A thick boundary layer will encourage the stall. The boundary layer is thicker at the wingtips therefore the tip is likely to stall before the root. When a tapered wing is also swept, the tip stalling trend is enhanced by the span wise airflow towards the tip, particularly at low speed and high lift hence the need to avoid a grossly large taper ratio.
- The degree of this trend is modified by the varying use of built-in wing twist; span wise aerofoil variation, vortex generators, in the gear/flap configuration, and leading edge and trailing edge devices. Reducing sweepback using crescent shaped wings may be a possibility.
Does a jet have a critical engine?
- On a jet there is no critical engine in a nil wind situation. Its VMCA in the flight manual is a fixed speed and does not change with the effects of a crosswind (during certification VMCA tests are conducted in zero wind and no nose-wheel steering). In a crosswind situation the preferred engine to lose would be the outboard downwind engine as the crosswind will aid in directional control opposing the yaw caused by the failed engine (due to weather cocking action of the cross wind against the vertical stabiliser). This effect will be exactly the same on the reverse side Thus on a 4 engine aircraft taking off with wind from right to left the No4 engine (right hand outboard) would be the critical engine (reference: Stanley Stewart – Flying the Big Jets).
- In the cruise the outboard engines in a 4 engined aircraft are considered to be the critical engines.
- (Upwind = engine upwind before weathercocking)
How many satellites are required for RAIM detection? Number of satellites required for RAIM detection AND exclusion?
- RAIM is a software algorithm that is available in some GPS receivers which gives an indication if the position solution given by the GPS receiver is OK to use.
- It is OK to use if the position solutions (latitude, longitude and altitude), worked out from any four of at least five or more GPS satellites, all fall within a pre-defined tolerance. If the solution falls outside this tolerance then a RAIM warning is given which is indicated on the receiver. This means that the accuracy of the position on the receiver can not be guaranteed at that point in time and so it is advisable not to use the GPS for navigation until this warning disappears.
- The RAIM availability (or ability of a GPS receiver to provide a RAIM warning) is dependent on the number of satellites available or in view by the GPS receiver. Remembering we need a minimum of five satellites to provide a RAIM warning.
- For RAIM detection and exclusion 6 satellites required. (Exclusion is to isolate the unacceptable satellite.)
- So, if there are less than this number at any point in time at some location then this is identified as a 'RAIM hole' (or RAIM unavailability).
- It is basically a function of the geometry of the GPS satellites overhead of the receiver. Additionally, some satellites may have been taken out for 'maintenance' by the owners of the GPS constellation - the U.S. Department of Defence (DoD). GPS NOTAMS or Notice Advisories to Navstar Users (NANUs as they are called) are disseminated by the DoD prior to any planned GPS satellite outage.
- Baro-aiding may be used to improve RAIM availability since the additional altitude information provided by baro-aiding effectively acts as an additional satellite.
- Baro-aiding will be made mandatory for IFR GPS use and will be included in New Zealand Civil Aviation Rules Part 91.
- IMPORTANT NOTE: GPS receivers that also provide RAIM prediction do not take into account GPS satellites which have been taken out of service for maintenance by the United States Department of Defence. Their RAIM predictions may not be accurate therefore. The RAIM Prediction Service takes both the satellite geometry and maintenance outages into account giving more accurate predictions.
- The RAIM Prediction Service provides RAIM outage information for aerodromes with a published GPS approach and some additional aerodromes as a check of RAIM coverage.
- RAIM outage data is computed once per day (at 1400 UTC) or when a satellite outage NOTAM has been received. The computation is for the following 72 hour period.
What are the following MET abbreviations?
- FG = Fog
- BR = Mist (Brume)
- VA = Volcanic Ash
- GR = Hail (GS = Small hail)
- SN = Snow
- SQ = Squall
- TS = Thunderstorm
- SG = Snow grains
- PRFG = Partial Fog (covering part of aerodrome)
- PL = Ice pellets
- MIFG = shallow fog
- FU = smoke
- BCFG = fog patches
What is a Katabatic wind?
- A katabatic wind is a down-slope wind that develops as air cools in contact with cold ground and slips down the side of the hill
What are the parameters of CAVOK?
- Visibility better than 10km
- No cloud below 5’000 AGL or below minimum sector altitude whichever is the higher
- No CB’s, precipitation, drifting fog, dust devils etc
Centreline lighting becomes alternating red/white at what distance to the end of the runway? Centreline lighting becomes Red how much distance remains?
- Lighting will be coded to show white from the threshold to a point 914m from the runway end; alternating red and white from 914m to 300m from end; and red between 300m and runway end.
What are the speeds for holds?
- NORMAL CONDITIONS:
- 14,000 and below: 230kts and 170 kts (Cat A & B)
- 14,000 - 20,000: 240 kts
- 20,001 - 34,000: 265 kts
- Above 34,000: M0.83
- TURBULENT CONDITIONS:
- 14,000 and below: 280 kts and 170 kts (Cat A & B)
- 14,000 - 20,000: Lesser of 280 kts or M0.80
- 20,001 - 34,000: Lesser of 280 kts or M0.80
- Above 34,000: M0.83
Headwind component formula is...
- HWC = Surface wind x Cos Angle (Angle is between rwy and wind)
Crosswind component formula is...
CWC = Surface wind x Sin Angle (Angle is between rwy and wind)
- sin30 = .5 (with a wind from 30 degrees the cwc is half the total wind)
- sin50 = .75 (with a wind from 50 degrees the cwc is 3/4 the total wind)
- sin60 = .9 (with a wind from 60 degrees the cwc is the total wind minus 10%)
- sin80 = 1.0 (any wind of more than 80 degrees and your cwc is the total wind)
- CLOCK METHOD
- Think of the degrees off the nose as portions of the hour, so >= 60 degrees - 60 minutes - the whole hour - i.e. it's all crosswind
- 45 degrees - three quarters hours - three quarters is crosswind component.
- 30 degrees - 30 minutes - half hour - half is crosswind, etc, etc
Flying Wellington to Chathams ETP of 1hr 50min, you are 10min ahead of flight plan (tail wind) what effect on ETP? Will it be closer to Wellington or Chathams?
What does sweepback do for stability and critical mach?
The primary purpose of sweepback is to increase the value of MCRIT for a given aircraft. Since only the component of the relative airflow across the wing which is parallel with the chord line can be considered as producing/creating lift, only the vector speed of this chordwise component is significant when considering MCRIT. In effect, the wing is persuaded to believe that it is flying slower than it really is; this means that the airspeed can be increased before the effective chordwise component becomes sonic and thus the critical Mach # is raised. This is why a high speed a/c has a swept wing. As the thickness/chord ratio defines the amount of acceleration imposed on the upper surface stream it follows that the thinner the wing, the lower the acceleration, and the higher will be the airspeed before, for this reason alone, the upper flow becomes sonic. This is why a high speed a/c has a thin swept wing.
- ???Lateral stability (about the longitudinal axis) is reduced. If a straight wing aircraft is yawing it also rolls; this tendency is increased in a swept wing aircraft because the effective spans on both wings are altered. With yaw, both values of V and CL are increased on the outer wing and reduced on the inner wing posing a very marked tendency to roll the aircraft.
- Longitudinal stability (about the lateral axis) is also reduced due to the effects of mach tuck.
Dihedral provides what stability about what axis? Why do we use dihedral?
- Dihedral is the angle between the mainplanes (or tailplane) and the horizontal. If the planes are inclined upwards towards the wingtips this is positive and is called dihedral, if downwards this is negative and called anhedral. Anhedral is used for dynamic stability.
- Dihedral is an aid to lateral stability (about the aircraft longitudinal axis).
Static vent blocked effect on altimeter in climb (over read/under read)?
- Altimeter will read at altitude where it became blocked as it only reads static pressure – therefore under-read.
At what cabin alt does crew require supplemental O2? What are the oxygen rules?
- Pressurised Aircraft when cabin exceeds 10,000ft
- Crew supplemental oxygen to be used
- Crew supplemental and portable oxygen to be used if away from station.
- Pressurised aircraft between FL350-410
- 1 pilot at controls must be wearing mask which is supplemental or automatic whenever cabin is above FL130
- Or if 2 pilots at controls must have access to masks in 5 seconds
- Pressurised aircraft above FL410
- I pilot at controls wearing mask at all times
- Pressurised aircraft in event of pressurisation
- Unless aircraft can descend below FL140 in 4 minutes then supplemental oxygen for each passenger to be used whenever cabin is above FL140.
For flights above FL250, all passengers must be demonstrated use of oxygen during the passenger briefing.
- Unpressurised Aircraft
- When above FL130 continuous oxygen for pax and crew
- Between 10,000 and FL130 for more than 30 minutes continuous oxygen for crew and supplemental for passengers.
- 1013.25 hpa reducing by 1 Hpa per 27 feet
- Lapse Rate is 1.98°C per 1000’ up to 36 090’ then –56.5°C
- Changes are expected to last for a period of less than an hour and sufficiently infrequently foir the prevailing conditions to remain as reported.
- Intermittent changes are expected to last for a period of less than 30 minutes and take place sufficiently infrequently for the prevailing conditions to remain unchanged.
Which part and stage of a thunderstorm will have the most ice and turbulence?
- Icing – worst at point just above the freezing level from 0° to -10°c
- Turbulence – worst ahead of and below CB
Explain Advection/Sea fog?
- Advection fog occurs when a warm moist air mass moves over a progressively colder surface. Moist air masses move pole wards over progressively colder waters – resulting in sea fog and most commonly occurs in the warm sectors of depressions. Maybe widespread and persistent even in moderate winds.
If two aircraft are approaching each other head on and are 225 nm apart at 0000 UTC, what time will they pass if aircraft 1 is doing 420kts and aircraft 2 is doing 480 kts?
- Closing speed is 900 knots: 225/900 = 0.25 = 15 minutes = 0015UTC
TAS 120kts, Tailwind 60 kts (a-b), Fuel burn 100 kgs/hr. If the aircraft burns 100 kgs in a journey from a-b what will it burn from b-a.
- A-B = 1 hour @ GS 180 knots = 180 nm. GS for return = 60 knots = 3 hours = 300kg
Burn 8kg/nm. Range with a ton of gas?
Specific range = 125 nm
Definition of second segment.
- The second segment is from gear retraction to level acceleration altitude, which is normally a minimum of 400’ above the takeoff surface. In this segment the gear
- is retracted, the flaps are in the takeoff position and the aircraft is set in takeoff power. The speed is equal to V2 (initial climb out speed) and the required minimum gross gradient of climb, in a two engined aircraft, is
- 2.4%. The net flight path gradient is the gross flight path gradient reduced by 0.8%, i.e. 1.6%
- Landing gear is retracted
- The flaps are still in the takeoff position
- The speed is V2
- The minimum gross climb gradient in a twin engined aircraft is 2.4%
- The minimum net climb gradient in a twin engined aircraft is 1.6%; and
- Takeoff power is still set.
In what situation is MCRIT at its lowest value?
- When the aircraft is at high altitude – as cold temperature means that LSS is lower than at sea level
If climbing at constant Mach No. What happens to TAS and LSS?
- LSS will decrease with a decrease in temperature so at a constant Mach number the TAS will decrease in the climb.
What happens to MCRIT with decrease in weight?
- A decrease in weight will increase MCRIT due to reduced angle of attack required
How would an aircraft reach MCRIT for the lowest TAS?
- When LSS is at its lowest value; i.e. for any range of options the highest and coldest option
Effect of flap on drag
- An increase in flap setting increases lift and drag.
Effect of flap on angle of attack at the point of stall
- The use of flap increases the CL of the wing by increasing the camber, therefore a higher angle of attack (effective) can be reached before the stall when compared with a flapless wing. Flap increases the effective angle of attack at the stall and reduces the geometric angle of attack and the stall speed.
Boundary layer does what as airflow goes from laminar to turbulent?
- The boundary layer thickens in depth and produces more drag and less lift
Reason for all-moving tailplane?
- Requirement of a large C of G range (large weight changes).
- Need to cover a large speed range
- Need to cope with large trim changes due to wing
- loading and trailing edge high lift devices without limiting the amount of elevator remaining.
- Need to reduce trim drag.
What assists longitudinal stability? (Fin, Tailplane or dihedral)
To correct for a nose heavy aircraft with a variable incidence tailplane, the angle of incidence would ___________ and the leading edge on the tailplane would __________?
- To balance this a downwards force, or a reduction in upwards force is required from the tailplane therefore the angle of incidence would decrease (maybe even negative) and the leading edge would lower.
In a roll to the right which spoiler extends and which aileron goes down?
- Right spoiler extends and left aileron goes down.
What is the definition of Part 121?
- Air Operation - Large Aeroplanes
- Part 121 is to prescribe the operating requirements for air operations of aeroplanes that have a passenger seating configuration of more than 30 seats, excluding any required crew member seat, or a payload capacity of more than 3410 kg, carried out by the holder of an Airline Air Operator Certificate issued under Part 119 of the Rules
Instrument rating currency requirement.
Demonstrateed competency to an examiner preceding 12 months (60 days before is ok), in a conventional non-centreline mullti-engine aircraft.
In the preceding 3 months, not less than 3 hours instrument time (1 hour flight time) in appropriate category - OR otherwise the above within 3 months.
Within preceeding 3 months performed 3 published approaches, one can be in approved simulatator.
Prior to carrying out an approach, must have completed one of similar type in preceeding 3 months in flight or approved simulator.
- Similar types are:
- ILS and PAR
- VOR, NDB, LOC
Documents to be carried on Air Operation under Pt121?
Documents required on an international flight?
Part 121.855 Documents to be carried on each Air operation:
(a) Each holder of an air operator certificate shall ensure that the following documents are carried on each individual air operation—
(1) details of the operational flight plan; and
(2) NOTAM and aeronautical information service briefing documentation appropriate to the operation; and
(3) meteorological information appropriate to the operation; and
(4) the load manifest; and
(5) notification of dangerous goods; and
(6) copies of the relevant flight guide charts and plates; and
(7) in the case of a regular air transport service, a route guide covering each route flown and alternate aerodromes that may be used.
- (b) The holder of an air operator certificate shall ensure that separate copies of the documents referred to in paragraph (a)(7) are available for each pilot performing flight crew duties on the
- C of A
- Aircraft Registration
- Flight Crew Licences
- Valid Maintenance. Release
- Load Sheet
- Flight records
- List of Crew & Passengers
- Cargo bills of lading and manifests
- List of disposable stores and spare parts
- Route Guide (if scheduled)
- Flight Plan
- Met information
- Flight Guide
- Dangerous goods notification
How far out can an ETA be before you must tell ATC?
When can you descend below MDA on circling approach?
When continuous visual reference to terrain is established.
Visibility is equal to or greater than the prescribed minimum for the procedure.
The approach permits a landing to be made using normal manoeuvring and descent rates.
- Except for Cat II and Cat III ILS, one of the following is distinctly visible:
- -the approach lighting system,
- -the threshold markings,
- -the threshold lights,
- -the runway end identification lights,
- -the visual approach slope indicator,
- -the touchdown zone or touchdown zone markings,
- -the touchdown zone lights,
- -the runway or runway markings,
- -the runway lights.
Also for circling approaches: visual reference must be maintained throughout circling,
The pilot can see runway threshold lights, approach lights or any other markings which identify the approach end of the runway, and
Obstacle clearance can be maintained to a point from where a constant rate of descent can be held to the intended touchdown point.
If you go IMC circling downwind? Do you execute the MAP for the “Active” runway or “approach” runway?
Execute the missed approach procedure for the approach that you were on.
- It is expected that the pilot will make an initial climbing turn towards the landing runway and overhead the aerodrome where the pilot will establish the aircraft on the missed approach track. Different patterns will be required to establish the aircraft on the prescribed missed approach course depending on its position at the time that visual reference is lost
What separation is provided by between IFR and VFR traffic in class C and D airspace?
- Class C = IFR separation from IFR, VFR and SVFR
- Class D = IFR from IFR and SVFR but traffic information is passed on VFR
If you are under ATC speed control, how close to the assigned airspeed must you fly?
- Within 10 knots of assigned speed
If the marker beacons are NOTAM U/S for an ILS; what minima can you go to?
- To ILS minima as long as alternate fix altitudes are nominated on the IAC or NOTAM and are used for altitude checks. Air NZ flight NZ60!!!! Erroneous Glideslope
What errors does the mach meter NOT suffer from?
- Compressibility and density
What happens to the altimeter if increase baro scale.
- As the altimeter will sense a greater differential the hands will go up
When will TCAS II not give an RA
- -During GPWS warnings.
- -Also approx 900 ft rad alt and below, no decent advisory below approx 1500 ft rad alt.
A RA - Resolution Advisory depicted by a solid red square is provided when another transponder equipped aircraft is within 20 - 35 sec’s and within 600ft. Avoidance action is required.
A TA is a yellow circle when traffic is within 25 - 45 sec and 850ft. Aural TRAFFIC alert.
If GPS satellites orbit the earth every 12 hours, how does a GPS receiver know where to look when first turned on?
- The GPS database carries an “Almanac” of satellite positions and any changes are transmitted to the GPS receiver by means of Service messages
Regulation of AC voltage
- Through use of a CSD (Constant Speed Drive)
How do you control AC current?
- Through a Generator Control Unit (GCU)
Why do we heat fuel?
- To prevent fuel freezing due to low ambient temperatures
Purpose of bonding regarding static charges?
- To ensure that all sections of the airframe havethe same potential and therefore prevent arcing
For V2 over-speed take offs what are the obstacle considerations
- Close in obstacle clearance reduced
- Distant obstacles cleared better due to higher speed
What is the advantage of an increased V2?
- An improved climb gradient
- An increase in Take off weight
What are the advantages of a swept wing?
- It allows a high mach number cruise speed due to it’s lower drag. This is because the swept wing is only sensitive to the component of airflow velocity across the
- chord of the wing. The apparent airspeed across the chord is less than the real airspeed. This means that wing can be flown to a higher speed before the critical mach number is reached. Obviously a thin wing is also required so as reduce the camber and so reduce the acceleration of air over the upper surface.
What are the disadvantages of a swept wing?
- It can be subject to tip stalling which due to the wing tips being behind the center of gravity causes pitch up.
- This has largely been fixed by washout (reducing the incidence at the wingtips so the wingroot stalls first).
- It has a higher stall speed because the sweep reduces the lift in the same way it reduces the drag. This means that advanced and complicated flap and leading edge devices
- are required to reduce the airspeeds for takeoff and landing.
It requires a higher angle of attack to produce the same amount of lift as an unswept wing. This produces high nose up attitudes for takeoff (possibility of tailstrikes) and landing. Also means that the profile drag is more – higher thrust required on approach and landing.
- It has poor oscillatory stability. It has marked roll with yaw due to the reduced sweepback on the advancing wing producing more lift and also the increased projected
- span. This leads to Dutch Roll.
On swept wing aircraft with podded engines far out on the wing, there is an increased possibility of scrapping them on the runway on takeoff or landing if the aircraft is rolled significantly. This is because the outer part of the wing is behind the main gear which is the pivot for the manoeuvre.
How would you reduce Dutch Yaw if designing an aircraft?
- For the same amount of sweepback you could enlarge the fin and rudder. This would make it more directionally stable butless stable laterally possibly giving spiral instability. You could reduce the sweepback. Yaw dampers are also used.
How does a Yaw Damper work?
- It is a gyro system that is sensitive to changes in yaw which feeds a signal into the rudder controls so that rudder is applied to oppose the yaw.
How do you stop Dutch Roll in flight?
- You apply opposite aileron to the up going wing.
What happens when the Critical Mach Number is reached?
A shockwave may form which increases drag, reduces lift, moves the center of pressure, and can cause buffeting.
- At the shockwave, the velocity falls but the pressure, temperature, and density all increase. More pressure equals less lift – more drag. As the mach number is increased above the critical mach number, the shockwave becomes more developed and moves backwards.
Why does the aircraft tend to pitch nose down when the Critical Mach number is reached? (Mach Tuck)
There are 3 reasons.
The shockwave on the upper surface upsets the lift distribution chordwise and causes the center of lift to move rearwards.
The swept wing tends to experience shock wave effect first at the wing root because this is thickest and has a higher angle of incidence. This causes a loss of lift inboard and thus forwards.
- The shockwave can cause a reduction in downwash over the tailplane.
What would you do to recover the aircraft from a MMO overspeed?
- Deploy the speed brake, roll aircraft level, hold back elevator pressure, use the elevator / stabiliser trim in small amounts.
- Power levers may be closed depending on the aircraft type. I.e. 747 – 400 low thrust line – closing power levers will reduce thrust causing more pitch down.
Which part of the wing normally stalls first?
- The wingroot.
- The reason for this is so that you still have roll control and so that the nose pitches down on a swept wing aircraft. This is a stable movement.
Earlier aircraft without enough washout stalled at the tips first which pitched the aircraft up further increasing the angle of attack and drag. Aircraft with T tails suffered lack of tailplane and elevator effectiveness because the tail was in the path of the disturbed air coming off the wing. These aircraft became superstalled or deepstalled, and some could not be recovered. Thus stickshakers and stickpushers were developed for aircraft with unacceptable stall characteristics.
What is a Mach Trimmer?
It is a device fitted to some Jet aircraft which trims the stabiliser up at mach numbers exceeding MCrit. It is used because some aircraft experience either lack of elevator effectiveness or very heavy elevator forces at high mach numbers above MCrit.
(During high speed flight, an aircraft is subject to rearward movement of the wings centre of pressure causing a nose down pitching moment. This is commonly known as TUCK UNDER. At supersonic speed the use of trim tabs etc has little effect on the pitching movement of the aircraft. Mach trim can be achieved in two ways:one way is to effect the centre of gravity of the aircraft by using the fuel as the trimming medium. If the centre of gravity is to far forward giving a nose down pitching moment fuel can be transferred rearwards, thus restoring the aircraft to normal flight by raising the nose.This type of trim is normally carried out by flight crew, guided by intrumentation that indicates aircraft cg at all times.The more poular method of mach trimming is to use a mach trim system. From design studies, the point at which the pitch down conditions occur is known to the aircraft designers. Say for instance, it occurs in a certain aircraft at mach 0.85. By having sensors and drive motors coupled to the pitot statics system a signal will be generated to the mach trim system at mach 0.85. This then sends on signals to the automatic flight control system, which in turn will carry out small trim changes to the horizontal stabilisers or the all moving tailplane to counteract the tendancy to tuck under.)
How is stability affected by high speed, high altitude flight?
Aerodynamic damping is reduced at high altitude. There is less restoring force when a displacement happens. ½ Rho V2 is the reason why (less lift). Less air density at high altitude and the V2 forces are not high as V2 is based on IAS.
- Directional control can be affected. If right rudder is applied it can accelerate the left wing to it’s critical mach number which thus loses lift and has increased drag so the
- aircraft yaws to the left and rolls left. This means that spiral stability is increased. The aircraft won’t enter a spiral dive.
- Lateral control can be affected as normally the outboard ailerons are locked out due to wing twist that they cause leading to an opposite roll. Thus only the inboard
- ailerons are available and possibly the differential spoilers. Oscillatory stability is reduced due to less roll control.
Longitudinal stability is reduced. (See Mach Tuck, Mach trimmers)
Note: spoilers are normally locked out as well due to the high drag penalties associated with their use at high speed.
- Aerodynamic definition: Whenever in-flight maneuvers result in rotation of an aircraft about or near its center of gravity, a restoring moment is created by the changed relative airflow. This restoring moment opposes the control demands, and it arrests maneuvers as and when the control demands cease. The effectiveness of the restoring moment (known as aerodynamic damping) is dependent on the dynamic pressure (i.e., indicated air speed). As altitude increases, true air speed increases for the given equivalent air speed, resulting in decreased aerodynamic forces. Thus, at higher altitudes the pilot must apply greater opposite control movements to arrest rotation.
How do designers increase the Critical Mach Number of an aircraft?
Number of ways:
Lift / Drag Formula: ½ Rho V2 S CL ½Rho V2 S CD
Low Wing Area: A larger wing will have increased drag but better lift.
Aspect Ratio: High aspect ratio causes less induced drag but can be a problem for the structural people. I.e. High bending forces involved and also a very thick wing root to support the long wing. A thick wing has a lower critical mach number so it is a tradeoff in many respects.
- Sweep: To little sweep causes a high drag rise at a low mach number. Too much sweep causes poor oscillatory stability and a tendency for the tips to stall. Also as fuel burns off there is a large center of gravity change in a
- highly swept wing.
Taper: This is the ratio of root chord to the wingtip chord. Optimum is about 2 ½ to 1. Each section of the wing will produce the correct proportion of lift. If it is too small then the wing will be heavier from a structural point of view. If too large then high local coefficients of lift are produced which tends to make the tips stall first or the wing to suffer bad stalling characteristics.
- Thickness / Chord Ratio: A thin wing is required for high mach numbers. A thick wing is required for structural strength, accommodating fuel, landing gear, flaps, and also to lower the stalling speeds.
Why is a 747 – 400 loaded or flown with an aft C of G?
- Because then the stabiliser is trimmed so as to produce lift. This means that there is more lift to drag so the aircraft will fly further or use less fuel for a given flight.
How does an aft C of G affect stability?
- It reduces longitudinal and directional stability. Stabiliser and Fin, elevator and rudder effectiveness are reduced.
- The further aft the CP the more it gives a pitch up movement after a disturbance. The further aft the C of G, the shorter the restoring arm for the rudder and elevator.
What are the advantages and disadvantages of engines mounted on the wings?
Engines provide bending relief thus reducing wing structure weight.
Intake efficiency is not compromised except perhaps in reverse.
The wing profile is not compromised.
At high angles of attack the engine pylons tend to act as fences, controlling spanwise flow.
Interference drag is low.
Thrust reverser design is not compromised.
Engine accessibility is good.
Less containment devices needed in the event of failure.
More yaw following engine failure. Bigger rudders and fins required.
Roll freedom can be limited on the ground.
A low thrust line can cause pitch up with power and pitch down with reducing power.
The reversed flow from the inners can affect the outboards on a 4 engined type on landing.
FOD damage is higher.
How do you fly for best range?
- You have to cover the most ground nautical miles per pound of fuel used. In terms of engine efficiency this is achieved at high RPM which can only be achieved at high altitudes with jet engines. In terms of airframe efficiency it is achieved at the lowest drag to airspeed / thrust / fuel consumption. At high altitudes the TAS is greater for a given IAS so more nautical miles will be covered than at low altitudes so flying high has
- two advantages – better groundspeeds and better fuel efficiency.
How do you fly for best endurance?
You have to stay airborne as long as possible on a given amount of fuel. The lowest fuel consumption rate is needed. Minimum drag and hence minimum thrust is required. Altitude improves endurance as turbine engines are more efficient at the higher RPMs necessary to maintain the minimum thrust at altitude.
- Jets at high altitudes
- Piston- sea level
- Turbo-props below 10,000ft.
Why are high bypass engines more efficient than low bypass engines?
Propulsive efficiency is made up of the Froude Efficiency (the thrust power produced divided by the kinetic energy added to the air).
U is the speed of the aircraft and V is the jet velocity relative to the aircraft.
High bypass engines moves a large mass of air and accelerates it to a reasonably high speed. This is most efficient up to quite high mach numbers.
Low bypass engines move a smaller amount of air but accelerate it to a lot high speed. This is only efficient at very high mach numbers.
The high bypass engine is thus more efficient and achieves a lower Specific Fuel Consumption (lb of fuel / lb of thrust / per hour)
Also high bypass engines are less noisy.
What is bypass ratio?
It is the ratio of air that does not enter the turbine section of the engine to the ratio that does. I.e. If 10 parts of air goes does not enter the engine and 1 part does, the engine has a 10:1 bypass ratio. q284
What is the advantage of the 3 Spool engine?
It has greater efficiency over a wider range of operating conditions.
Each spool can be rotated at it’s optimum design speed.
It is also less noisy.
Easier to start.
The front spool sections rotate slower and thus achieve better reliability.
A 3 spool engine is one that has three sets of compressors before the combustor and three sets of turbines behind it.A spool is made up of a compressor and a corresponding turbine used to extract the power from the exhaust gasses to turn the compressor.Each spool is given a name. N1, N2, and N3. N1 is the large fan section in front of the engine. N2 is the low pressure compressor section. And N3 is the high pressure compressor section. Some engines incorporate N2 And N3 into one rotating mass and call it N2. Hence the double spool engine.Each section of the compressor wants to rotate at it's own speed, and if allowed to do so as in a triple spool engine, it is able to operate more efficiently. It can turn at it's optimum speed, and not have to compromise between the optimum speed for the N2 and N3 sections when attached in the double spool engine
- More sets of blades results in a greater engine weight, but the corresponding increase in thrust possible more than offsets the weight increase.Major advantage of triple spool engine design is it's ability to minimise engine surgesThe drawbacks of a 3 spool engine are increased weight, complexity, and cost to purchase and overhaul, but they are the most efficient engine flying.
Does a jet aircraft have a critical engine?
- Only on takeoff in crosswinds. A four engined type such as the Boeing 747 – 400 obviously has the outer engines give more yaw if they fail due to moment arm.
What performance category does your aircraft come under?
The Beech 1900D is certified as a Part 125 aircraft in NZ. This means it has performance equivalent to FAA FAR 23 Amendment 34 certified in 1991.
The climb requirements are:
- A: Takeoff, Landing Gear Extended (1st Segment)
- Configuration: Flaps 17, Gear Down
- Power: Critical Engine Inop, Remaining Engine at maximum T/O power
- Speed: V2
- Gradient: Not less than 0%
- B: Takeoff, Landing Gear Retracted (2nd Segment)
- Configuration: Flaps 10, Gear Up
- Power and Speed: As Above
- Altitude: Climb to 400 Ft
- Gradient: Not less than 2.0%
- C: Accelerate, Flaps Retracting (3rd Segment)
- Configuration: Flaps Up, Gear Up.
- Power: As Above
- Altitude: 400 Ft AGL
- Gradient: Not less than 0%
- D: Enroute Climb, Flaps Retracted (4th Segment)
- Configuration: Flaps Up, Gear Up
- Power: MCP
- Altitude: Climb to 1500 Ft AGL
- Gradient: Not less than 1.2%
What is V1?
It is the speed at which the aircraft, having suffered a failure of the critical engine, can either continue the takeoff safely or stop in the remaining distance.
It is the speed by which the pilot should have made the decision to continue the takeoff or reject it.
- It allows for an engine failure, 1 second for the pilot to
- recognise it, 1 second for the decision to stop, and 1 second for the change to be made to maximum braking. Which equals 2 seconds to transition from take off to stopping.
What is Vr?
- It is the rotate speed. It permits obtainment of V2 by 35 feet AGL. It cannot be less than V1 or 1.05 Vmca .
What is V2?
- It is the second segment climb speed. It allows the aircraft to achieve the minimum climb gradient. It cannot be less than 1.2 Vs or 1.1 Vmca.
What is the Vmca of your aircraft?
- 92 knots with flap up or flap 17
Tell us about aquaplaning.
It is caused by a layer of water that builds up an increasing resistance to displacement and finally results in a wedge being created that separates the tyre from the runway. When the tyre is completely separated from the runway the braking effectiveness is reduced to that of an icy runway.
Dynamic aquaplaning occurs when there is standing water and the tyre lifts off the runway completely. Use formula for this.
Viscous aquaplaning occurs when the surface is damp and the film of water cannot be penetrated by the tyre. Can occur down to lower speeds than dynamic aquaplaning. Ususally from very smooth surface e.g. too much rubber on rwy.
Reverted rubber aquaplaning occurs when the tyre builds up a tremendous amount of heat during a skid and reverts allowing hardly any tread to disperse the water. Heat friction boils water into steam, lifting centre of tyre up. Only tyre edges touch rwy, traping steam under centre of tyre. Effectively it is like braking with no tread on the tyres. Leaves marks on runway.
- 3mm water depth is required to call a runway contaminated.
What is Ground Effect?
Ground effect occurs when the aircraft is low enough that the downwash angle of the airflow from the wing is altered by the ground. This tilts the rearward component of lift forward which reduces the drag.
Discovered during WWII when heavy bombers with engines out were forced low over the ground or water, unable to maintain height. Often they would encounter ground effect which enabled them to stay airborne. Jolly good show old chap!
What instruments does the Central Air Data computer run on your aircraft?
Flight Data Recorder
Recieves inputs from the pitot tubes, static vents, and temperature probe.
Tell us about gyros and wander.
Due to it’s rigidity, the spin axis of a perfect gyro should continue to point in a fixed directio. Any movement away from this direction is known as Gyro Wander.
Real Wander occurs when the gyro actually moves relative to a fixed point in space. It may be real drift or real topple. It is caused by frictional forces giving unwanted precession. Max error allowed is 4 degrees per 15 minutes, or 16 degrees per hour.
Apparent Wander occurs when the spin axis of a gyro appears to change direction to a earthbound observer, such as when the earth rotates. Apparent wander also occurs when the gyro is transported across the earth west or east. This is known as Transport Wander.
Transport wander is when flying a great circle (curved path) the gyro thinks your trurning when your not. Straight line on a sphere can seem curved.
Apparent Drift = 15 x sine of the latitude / hour
Apparent Topple = 15 x cosine of the latitude / hour
- There are four types of gyros:
- Space Gyro – Two gimbals, freedom of movement about 3 axes.
Tied Gyro – Two gimbals, freedom of movement in 3 planes but controlled by an external force. Directional Gyro (DI)
Earth Gyro – Two gimbals, freedom of movement in 3 palnes but controlled by gravity. Artificial Horizon.
Rate Gyro – One gimbal, freedom of movement about 2 axes, 1 of which is the spin axis. INS platforms make use of rate gyros. Turn Co-ordinator.
- Earth Rate : 15 x sin mean lat
- N: - S: +
- Latitude Nut: 15 x sin Latitiude of setting
- N: + S: -
- Transports Wander EAST: N - S +
- Transport Wander WEST: N + S -
Real Wander: As in operating manual
What do you know about INS or IRS?
INS – Inertial Navigation System
IRS – Inertial Reference System
INS systems these days are of the Strapdown type where there is no gimbal system on which the gyros and accelerometers are fixed. Rather they are physically strapped to the aircraft structure. The system uses laser ring gyros rather than conventional ones. Prior to flight the system is initialised and the co-ordinates of the ramp position and route waypoints are entered. A computer then builds a reference and stores this in memory. All aircraft movements are then relative to this memory model.
- It is more reliable than the old stable platform system because it contains fewer moving parts and does not
- require recalibration. It can also supply magnetic headings, as well as VSI and attitude information.
- Navigation Questions – Air New Zealand
How does a Laser Ring Gyro work?
- It consists of a solid block of triangular thermally insulated glass with a hole in the middle filled with a laser medium gas such as Neon or Helium (inert). Two lasers travel in opposite directions through this hole. When the gyro is rotated, one laser takes longer to complete it’s travel. The difference is picked up by optical sensors and given a digital readout.
- The advantages of the system over old gyros are:
- Available within 1 second after being switched on (no spin up).
- High reliability
- Not sensitive to acceleration (Gs)
- Sensitive to changes over a wide range – i.e. through all
- ranges of pitch, roll, yaw. (No topple)
What is the departure formula?
It is the formula which relates change of longitude to distance.
Distance (nm) = Change of longitude (in minutes of arc) x Cosine mean Latitude
Distance = d long ‘ x cos lat
Calculate the distance between 46 30 N 138 15 W and 36 15 N 122 45 W.
Distance = d long ‘ x cos mean lat
Distance = 930 x cos 41 22 30 (41.375)
Distance = 930 x .75
Distance = 698nm
Calculate the distance between 37 28 S 176 43 E and 20 15 S 168 23 W
Difference in Longitude = 14 54 x 60 = 894
Distance = d long ‘ x cos mean lat
Distance = 894 x cos 28 51
Distance = 894 x .876
Distance = 783 nm
Tell us about fractions.
- A fraction has two terms – the numerator (above the line) and the denominator (below the line). In order to add or subtract fractions, all the denominators must be alike. The numerators are then added or subtracted.
- ¼ + 2/4 = ¾
2/9 + 5/9 = 7/9
- When the denominators are unlike, it is necessary to reduce the fractions to a common denominator before adding or subtractiong. One way to do this is to multiply
- the two denominators together.
- 1/3 + 4/5 = 5/15
- + 12/15 = 17/15 or 1 2/15
- 2/7 + 3/9 =
- 18/63 + 21/63 = 39/63
- To add two or more mixed numbers,
- add the whole parts first then add the fractions.
- 5 ¼ + 3 2/3 = 8 + (1/4 + 2/3)
- = 8 + (3/12 + 8/12)
= 8 11/12
- 10 6/15 + 23
- 4/11 = 33 + (6/15 + 4/11)
= 33 + (66/165 + 60/165)
= 33 126/165
Subtraction follows the above principles.
- 7 2/3 – 6 2/9 = 1 – (2/3 – 2/9)
= 1 – (12/18 – 6/18)
= 1 6/18
= 1 1/3
To multiply two fractions, simply multiply the two numerators and the two denominators.
- 3/5 x 7/12 = 21/60
To multiply mixed numbers, the mixed number must first be changed to an improper fraction by multiplying the whole number by the denominator then adding the product to the numerator.
- 2 1/3 x 5 ¼
- becomes 7/3 x 21/4
7/3 x 21/4 = 147/12 which becomes 12 3/12 or 12 ¼
10 4/17 x 7 6/11 becomes 174/17 x 83/11
174/17 x 83/11 = 14442/187 which becomes 77 43/187
The simplest way to divide fractions is to invert the divisor fraction then multiply the numerators together and the denominators together.
6 ¾ / 1 ½ = 27/4 / 3/2
27/4 / 3/2 becomes 27/4 x 2/3 = 54/12 or 4 6/12 or 4 ½
5 7/8 / 3 2/5 = 47/8 / 17/5
47/8 / 17/5 becomes 47/8 x 5/17 = 235/136 or 1 99/136
Tell us about Trigonometrical Functions.
Sine of an angle may be determined by constructing a right- angled triangle, where the hypotenuse and an adjacent side subtend the angle in question. If the length of the side opposite this angle is divided by the length of the hypotenuse, the numerical result is the sine of the angle. Remember, the hypotenuse is always the side opposite the right angle, the third side is termed the adjacent.
Tell us about the 1 in Sixty Rule.
- Track Error Angle = Distance Off x 60. Distance Gone
- Closing Angle = Distance Off x 60
- . Distance To Go
How do you work out the Local Speed of Sound?
- LSS = 38.94 x Temperature (K)
- The local speed of sound varies only with temperature. Therefore as the temperature normally decreases with altitude, the local speed of sound reduces and for a constant TAS the Mach Number will increase.
What is Earth Convergency?
- It is the angle of inclination between any two meridians at a given latitude. It can be described as being the difference between a great circle track angle measured at one of the meridians and the great circle track angle measured at the other meridian.
- Earth Convergency = change of longitude x sine of the mean latitude
What do you know about conversion angle?
- When you fly between two points it is usual to use either a great circle track or a rhumb line track (constant track angle). The angle subtended between these two tracks
- at the departure point is equal to the angle subtended at the arrival point and is termed the conversion angle.
- The conversion angle is equal to half the value of earth convergency between the departure point and the arrival point.
- Conversion Angle = 0.5 x change of longitude x sine of the mean latitude
Formula for speed (kts)
Speed (kts) = distance (nm) Time (hrs). q305
Formula for Distance?
Distance (nm) = Speed (kts) x time (hrs). q306
Using One in Sixty Rule, what is the formula for Track error angle and also for closing angle?
Track error angle = Distance off x 60 Distance gone (hypot)
Closing Angle = Distance off x 60 Distance to go (hypot)
If another aircraft at the some height get closer, how do you know if you're on a collision course?
the relative bearing of that aircraft remains constant. q308
What is a rhumb line?
- A regularly curved line on the surface of the earth which cuts all meridians at the same angle.
What are parallels of latitude?
Small circles drawn on the surface of the earth, joining points of equal latitude, so they are parallel to the equator. All parallels of latitude (other than the equator) are small circles and all parallels of latitude (including the equator) are rhumb lines. Numbered from 1-89 degrees north and south.
What are meridians?
- Semi-great circles passing throught the poles which are used to define position in longitude. All meridians point north-south. Whole degrees of meridians are number 1 to 179 degrees east and west of the prime meridian (0 degrees). The prime ante-meridian is 180 degrees east/west. An ante-meridian is a meridian which lies 180 degrees from the meridian in question, together they form a great circle.
What is latitude and longitude?
Is the angle between the equator and the parallel of latitude, from the centre of the earth. It is the arc of the meridian intercepted.
Longitude is the arc of the equator intercepted between the prime meridian and the meridian passing through the point.
One degree of latitude = how many minutes of arc and what distance?
One degree of longitiude = how many minutes of arc and what distance?
One degree of latitude = 60 minutes of arc which = 60nm
One degree of longitude = 60 mintues of arc which = 60nm BUT only at the equator (great circles only), therefore use formula to determine distance.
What is a great circle?
- A circle drawn on the surface of the earth which its radius is that of the earth and its plane passes through the centre of the earth. The shorter arc of a great circle is the shortest distance between any two points.
What is earth convergency?
- The angle of inclination between 2 meridians at a given latitude.
- The difference between a great circle track angle measured at one of these meridians and the same great circle track angle measured at the other.
- At the equator, earth convergency is zero, because all meridians are parallel with one another.
- Formula is Earth convergency = change of longitude (degrees) x sine of the mean latitude.
- EC = d long x sin mean lat
What is Conversion angle?
- When flying between one point and another it is usual to use either a great circle track (the shortest distance) or a rhumb line (with constant track angle). The angle between these 2 tracks at the departure point is equal to the angle between these tracks at the destination, this is called the conversion angle.
- Conversion angle = 0.5 x change in longitiude (degrees) x sine of the mean latitude
- CA = 0.5 x d long x sin mean lat
What 2 features must an orthomorphic chart have?
- 1. Equal scale expansion
- 2. Parallels of latitude must cross the meridians at right angles. q317
Explain a Mercator chart?
- Cylindrical projection
- All meridians appear as straight lines with constant spacing between each meridian
- The parallels of latitude also appear as straight lines, but the distance between increase with increases of latitude.
- Projecting the poles is impossible.
- The parallels of latitude cross the meridians at right angles.
- The scale expands as the secant of the latitude.
- All rhumb lines are shown as straight lines.
- All great circles (apart from meridians and equator) are shown as curved lines which are CONCAVE to the equator.
- Earth convergency is only correctly shown at the equator (zero).
Plotting radio waves on a Mercator Chart
- Radio waves travels along Great circles.
- Great circles are curved line CONCAVE to the equator when on a Mercator Chart.
- Radio can only be plotted along straight rhumb lines when on a Mercator chart.
- NDB/ADF bearings are measured at the aircraft, variation and conversion angle is applied at the aircraft.
- VOR/VDF bearings are measured at the station, variation and conversion angle is applied at the station.
Explain a Lambert Chart?
- Conical projection
- Cone touches the earth at the Parallel of Origin/Tangency or it is inset and touches at 2 latitudes called standard parallels.
- The meridians are straight lines which converge toward the poles.
- The parallels of latitude are curved lines.
- The parallels of latitude cross the meridians at right angles.
- Rhumb lines are curved lines concave to the nearest POLE.
- Great circles are shallow curves concave to the parallel of origin (assume they are straight for plotting purposes)
- Chart convergency = Earth convergency at the parallel of origin.
- Chart convergency = d long x sine of parallel or origin
What is Vmu
Max unstick speed.
Vr must meet a number of criteria, one of which its its relation to Vmu, the minimum speed at which lift off is possible. Due to the vertical component of thrust, the all-engines-operating Vmu is usually less than the one-engine-inop Vmu.
In either case Vmu can be limited by one or more of three criteria:
(a) the stall AoA in ground proximity,
(b) the maximum AoA attainable on the ground due to the airplane geometry with mainwheels on the runway and the tail touching the ground, or
(c) the minimum speed at which it is possible to lift the nosewheel off the runway at forward center of gravity.
Vmu= minimum speed at which lift off is possible without tailstrike
Vlof= speed at actual lift off when rotating at VR.
What is Vlof
- Lift off speed, occurs after rotate.
At 36000 ft you want to climb, SAT is -42. What ISA chart do you refer to for performance?
ISA-5, ISA+5, ISA=10 etc
ISA @36000= -56.5 so use ISA +15
What are the Mach meter errors?
1. Blockage error
: When static is blocked, at level flight Mach Meter will read correct. In climb, Mach Meter under read. In descend, Mach Meter will over read.
When pitot is blocked, at level flight Mach Meter will freeze. In climb, Mach Meter over read. In descend, Mach Meter will under read
2. Instrument error
: This error is due to small manufacturing imperfections, with small tolerances. The error is usually insignificant and in some cases, a correct table is provided with the instrument.
- 3. Position/Pressure error: The error is caused due to interference of dynamic pressure at static source. Position error causes Mach Meter to under read. The error is induced due to: a) Position of static source. b) Maneuver induced.
How do you work out ROC required?
ROC req = Climb gradient x groundspeed
What are the approach speeds for Cat C?
- CAT C
- Vat (1.3Vs) 121 - 140
- Initial App...160 - 240
- Final App...115 - 160
- 45/180 degree turn...1 min, 15 sec
What are the approach speeds Cat D?
- CAT D
- Vat (1.3Vs) 141 - 165
- Initial App...185 - 250
- Final App...130 - 185
- 45/180 degree turn...1 min, 15 sec
What is the outbound timing in the hold?
- At 14,000 ft or below = 1 minute
- Above 14,000 = 1.5 minutes
- QFE = Pressure above airfield
- QFF = Pressure at a place reduced to MSL using actual temp
- QNE = 1013.25 (29.92) Pressure altitude (Pressure at SL in ISA)
- QNH = Pressure at SL, reads altitude
What is 'The Compass'
- The Compass is the International Airline strategy, it is our guide for the next 3-5 years.
- The Compass has several components – the vision with its audacious $110m profit improvement goal,
- a set of behaviours and leadership principles required from all of us, and
- a set of 10 strategic missions.
- We want all Air New Zealanders, regardless of where they work and what they do, to understand the strategy at some level and be better educated about the broader business. This in turn will also give you the context you need when we announce the various tactics that will fall out of this strategy over the coming months and years.
- So we have developed a series of five film modules for you to watch.
- The objectives of the modules is to ensure everyone understands the burning platform for change, leaves with a good sense of The Compass strategic plan and 10 missions, and starts to internalise what they personally, as an Air New Zealander and a leader, need to do to help create a better performance.
What are GPS errors?
- Ephemeris error - error in data which defines satellite position.
- Multi-Path error - signal reaching receiver after bouncing off earth surface.
- Ionospheric Propagation - Ionosphere has charged particles which affect speed of the signal.
- Tropospheric Propagation - water vapour in the troposphere slow down GPS signals.
- Receiver error - difficulty in matching the receivers emitted code with the satellite.
- Interference - electromagnetic influences on board aircraft.
- Tracking Accuracy & Collision Avoidance.
- RECEIVER ERRORS:
- Clock error
- Maximu dilution of precision (PDOP)