Technical questions Flashcards
1
Q
Definition of V1?
A
- The speed beyond which the takeoff should no longer be aborted
- Also means the minimum speed in the takeoff, following the failure of the critical engine at VEF at which the pilot can continue the takeoff and achieve the required height above the takeoff surface within the distance available.
- V1 ≥VMCG
- V1 ≤ Vr
- V1 ≤ Vmbe (max break energy)
2
Q
Vr meaning and greater than which V speeds?
A
- Rotation speed. The speed at which the pilot begins to apply control inputs to cause the aircraft nose to pitch up, after which it will leave the ground.
- Vr ≥ V1
- Vr = 1.05Vmca
3
Q
Definition of V2?
A
- The airspeed at which the aircraft complies with those handling criteria associated with the climb after takeoff and the target speed to be attained at the 35’ screen height, assuming recognition of an engine failure at or after V1 and used to the point where acceleration to flap retraction speed is initiated.
- V2 = 1.2 VS
- V2 = 1.1 VMCA
4
Q
Definition of Vmca?
A
- The minimum airspeed at which, when the 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°.
- Must be greater than or equal to 1.2VS (with undercarriage retracted and flaps in takeoff position)
5
Q
Definition of Vmcg?
A
-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.
6
Q
Cat C speeds?
A
Defined by Vat = 121-140
Initial approach 160-240
Final Approach 115-160
Circling Max 180
Initial Missed 160
Final Missed 240
7
Q
Performance Group A aircraft? (Not Cat A)
A
- “capable of continuing a flight in IMC after failure of a critical engine at speed V1 & proceeding to a suitable aerodrome & landing’
8
Q
What is a stopway?
A
- Clear area immediately beyond runway & at least as wide capable of supporting aircraft for braking
9
Q
What is a Clearway?
A
- Clear area immediately beyond runway over which aircraft may fly at height of 35ft
10
Q
What is the ASDA?
A
- Accelerate-stop distance available
- Is the combined distance of runway and stop-way
11
Q
Balanced field length?
A
- ASDR = TODR
- A balanced field takeoff is a condition where the accelerate-stop distance required (ASDR) is equal to the takeoff distance required (TODR) for the aircraft weight, engine thrust, aircraft configuration and runway condition.
Factors affecting the balanced field length include:
the mass of the aircraft – higher mass results in slower acceleration and higher takeoff speed
engine thrust – affected by temperature and air pressure, but reduced thrust can also be deliberately selected by the pilot
density altitude – reduced air pressure or increased temperature increases minimum take off speed
aircraft configuration such as wing flap position
runway slope and runway wind component
runway conditions – a rough or soft field slows acceleration, a wet or icy field reduces braking
12
Q
How is ASDA calculated?
A
Distance to accelerate to V1 – 1 sec recognition – 2 sec transition phase – distance to bring aircraft to a stop
13
Q
How is TORR calculated? (TORR = Takeoff Run Required)
A
- Is distance required to accelerate to V1 – engine fail – continue to midway between VLOF & 35ft point
- Vlof = lift off speed
14
Q
State the climb segments
A
1st segment
35 ft to gear retracted (+ve roc)
2nd segment
End of 1st segment to 400 ft or higher flap retract height; at V2 (2.4% climb gradient req’d)
3rd segment
End of 2nd segment level acceleration to final climb speed (climb gradient cabability of
1.2%)
4th segment
End of 3rd segment to 1500 ft; at > 1.25 VS (min. climb gradient of 1.2%)
15
Q
For V2 over-speed take offs what are the obstacle considerations
A
Close in obstacle clearance reduced
Distant obstacles cleared better due to higher speed
16
Q
What is the advantage of an increased V2
A
An improved climb gradient
An increase in Take off weight
17
Q
The Net take off flight path is deemed to end when
A
The aircraft passes 1500 ft
18
Q
Explain the use of an extended second segment climb
A
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 & 3rd segment, the aircraft must be ‘clean’ by the 400 ft point if obstacle clearance is required in the final segment
19
Q
Reduced thrust take off’s are dependant on
A
Field length
Take off flight path (obstacles)
Engine inop climb gradients
Aircraft Take off weight
20
Q
What is the reduced screen height for a wet take-off
A
15ft (slightly less than half of 35ft)
( It is because the stopping distance in the wet is longer than in the dry. V1, therefore, is lower. Lower screen height therefore reqd..)
21
Q
State the critical engine on a jet during take-off
A
Nil in head wind
The most upwind engine in x-wind due to increased yaw if engine fails (weather cocking)
22
Q
What effect does a balanced field have on take-off performance
A
A balanced field means that it is critical that an abort is carried out immediately on EF recognition. Also that the t/o on one engine could be marginal if continued as a balanced field is a take off right on the performance limits for the given aircraft weight – not a favourable scenario
23
Q
Definition of 2nd segment of take-off path:
A
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%.
Conditions:
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.
24
Q
Definition of ISA:
A
1013.25 hPa
15°C
Lapse Rate is 1.98°C per 1000’ up to 36 090’ then –56.5°C
Density is 1.225 kg/m3
25
Temperature at 39 000’?
-56.5°C
26
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.
27
Airspeed in the climb – at a constant TAS / IAS / Mach No. What do each do?
Constant IAS – Both TAS & Mach No. increase
Constant Mach No – Both IAS & TAS decrease
Constant TAS – Mach No. increases, IAS decreases
28
What happens to the speed of sound with altitude / temperature
LSS reduces with altitude and with cooling temperatures
29
Mach Number formula
M = TAS/LSS
TAS = True Airspeed
LSS = Local speed of sound (38.94 Temp (K))
30
Explain airspeed errors
ICE T it's a P C D
```
I = IAS
C = CAS (IAS corrected for Position errors)
E = EAS (CAS corrected for Compressibiliity errors)
T = TAS (EAS corrected for Density errors)
```
31
What errors does a Mach Meter NOT suffer from?
Density error & Compressibility error.
- Compressibility is not an error of the Machmeter. It's taken care of by the ratio arm and the ranging arm giving us the ratio of TAS/LSS and taking the density of the air out of the equation.
32
The two capsules in a Mach Meter are what?
Airspeed (TAS)
Altitude calibration. (LSS)
(M = TAS/LSS )
33
MFS is
Free stream Mach number – airflow unaffected by the aircraft
34
Mach L is
Local Mach number – is the speed of air relative to the Local Speed of Sound measured at a point on the aircraft
35
MCRIT is
The lowest free stream Mach number at which mach 1 is reached on any part of the
aircraft
- Part of the aerofoil may be travelling faster than the speed of sound but not all of it
36
How does weight affect MCRIT?
An increase in weight will reduce MCRIT.
| lower Mcrit is bad for commercial jets
37
What happens with the centre of pressure 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
(forward then back then forward movement is known as the mach 'tuck')
38
Wave drag is
The separation of the airflow behind the shock wave
- Shock wave can usually begins from the trailing edge of the wing
- Expansion wave usually occurs over the aerofoil behind the shock wave
39
A shock stall is the result of
The boundary layer behind the shock wave becoming turbulent and separating, spilling rearwards and striking the tail plane, creating buffet and rearward CP movement. Rear movement of the CP causes nose to pitch down
- Vmo protects the aircraft from high-speed buffet which could result in high-speed buffet
40
Wing design for high speed flight takes into consideration
Minimal camber to delay shockwaves
Maneuverability
Low thickness chord ratio
41
The primary purpose of sweep back is to
Increase the value of the critical Mach No.
42
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.
43
Advantages of a swept wing?
MCRIT increased.
Higher economical cruise speed
Increased lateral (roll) stability
44
Disadvantages of sweepback
Lower Cl
Extensive use of high lift devices (slats, flaps)
High drag @ high AOA
Use of vortex generators, wing fences to reduce wingtip ‘pooling’
45
A swept wing aircraft pitches up / 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)
46
Wash out is
A decrease in incidence from root to tip – to prevent wing tip stall
Allows ailerons to maintain effectiveness for longer
47
What devices are used to prevent wing tip stall (spanwise flow)?
Wing fence
Saw tooth leading edge
Vortex generators
48
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
49
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.
50
Aspect ratio
= span (width)/ chord (length)
51
High Aspect ratio (subsonic speeds)
Better lift
Better lift/drag ratio
Less induced drag due reduced wing tip vortices
52
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.
53
If Mach tuck is not corrected the result will be?
The nose pitch down causes further speed increase which causes further movement rearwards of the CP which causes further nose pitch down.....etc
54
Oscillatory instability is
A combined yawing and rolling movement
55
Dutch roll is
Oscillatory instability when the rolling motion is predominant
56
A stabilising device to prevent Dutch roll is
A yaw damper (gyroscopically operated stabilisers)
57
Snaking is
Oscillatory instability when the yawing motion is predominant
58
Oscillatory instability is worse when
At high altitudes
| sweep back a/c @ low IAS
59
The aircraft’s aerodynamic ceiling is
The point at which the high airspeed mach buffet and low speed stall buffet merge
60
The aerodynamic ceiling of the aircraft is known as
Coffin Corner (A/C can not be made to go faster or slower)
61
The manoeuvre envelope must be
At an altitude and airspeed sufficient to avoid stalling and slow enough to avoid structural damage
62
Gliding angle depends on
Ratio of lift to drag ratio – greater weight does not effect gliding angle or range, does effect speed
63
Aircraft in a constant descent @ 300kts, how does weight affect glide angle?
The heavier the aircraft the earlier descent must commence. So the more shallow the glide angle.
64
The effect of wing twist from operating ailerons at height speed is
It will minimise the effect of the ailerons / reverse the effect altogether
65
At high speeds the ailerons are...
Locked out to prevent wing twisting, inboard ailerons are employed to provide roll as well as spoilers
66
How do spoilers work to provide roll
The spoilers are raised on the down going wing reducing the lift on that wing
67
What are the functions 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
68
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
69
Differential spoilers provide
Roll control when flight spoilers are in use and aileron input is given
70
What are the limitations of spoilers?
At high speed spoilers can blow back
71
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
72
‘Q’ feel is
An artificial method of providing the pilot with control column loading using either springs or hydraulics which provide variable loading proportional to airspeed
73
When does aileron droop occur
When flaps are extended (usually the inboard ailerons)
74
A Krueger flap does what
Extends forward of the leading edge providing an increase camber
- Not to be confused with leading edge slats, like a hook that comes out of leading edge (747)
75
An Aft / forward C of G has what effect on the stall speed
Aft decreases the stall speed and forward increases the stall speed
Aft CoG tailplane producing an up force to balance L/W couple
Forward CoG tailplane producing a downforce to balance lift/weight couple
76
Hydroplaning depends on what factors
```
Tyre pressure
Runway surface
Tread depth
Tyre speed
Water depth
Runway grooving
```
77
Hydroplaning speeds for a rotating and non-rotating wheel are
Rotating 9.0 x (square root)tyre pressure
| Non-rotating 7.7 x (square root)tyre pressure
78
Reduced thrust take offs are used when
There is a long runway available
| MTOW is low
79
Two methods of reduced thrust takeoffs are
Fixed derate (ie 10% - 20%)
| Assumed temperature (more common)
80
Using an assumed temperature RT (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
81
Factors that affect the engine thrust
Increase Mass airflow = Increase Thrust
Increase Temp = Decrease Thrust
Increase Humidity = Decrease Thrust
Increase Altitude = Decrease Thrust
82
Ram effect is
As the aircraft increases speed the increase in density and mass flow through the engine results in an increase in thrust
83
An increase in engine RPM results in
Higher mass air flow
SFC decreases
Higher temps
Thrust output increases
84
Two ways of measuring thrust are
EPR (the ratio of inlet pressure and turbine exit pressure)
N1 (low pressure rotor speed/fan speed)
85
Engine bleed air has what effect
EPR decreases
EGT increases
Thrust decreases
86
Compressor stall / surge is
A reverse flow of air through the engine caused by unstable air
87
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 from VFR at night. VFR from IFR at night.
“E” IFR from IFR. IFR from VFR at night. VFR from IFR at night.
88
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.
89
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.
90
What are 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
91
Met definitions of:
| BR, VA, FU, GR
BR – Mist
VA – Volcanic Ash
FU – Smoke
GR – Small hail &/or snow pellets
92
If the static port blocks during the climb, what will it read?
Whatever the reading was at the time of the blockage.
93
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.
94
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.
95
ETP is
Equi time point – a point enroute where it will take the same time to go back as it will to carry on
96
ETP Formula:
Dist to ETP = Dist x Ground Speed home/ GS onward + G/S home
With a tailwind out ETP will move closer to departure.
ETP moves into wind
97
PNR is
Point of no return – a point which is based on fuel (endurance) at which you have the fuel to return if req’d
98
PNR Formula:
Time to PNR (min.s) = Endurance (min.s) x GS home / GS out + G/S home
Dist to PNR = Endurance (hrs(decimals)) x GSout x GShome / GSout + GShome
99
Gross fuel flow (GFF) is calculated by:
GFF = Fuel flow divided by GS (answer is in kg/nm)
Fuel flow (kg/hr)
GS (nm/hr)
100
How do we fly an aircraft for best 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 Jet aircraft). Piston engine aircraft should fly as low as possible for max endurance due to difference in power required. Propeller efficiency decreases with altitude
101
How do we fly an aircraft for best range?
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.
102
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.
103
Range vs Endurance, which speed will be lower?
Speed for max endurance will always be lower than speed for max range
104
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.
105
How does thrust vary with fuel burn at a constant speed?
Thrust reduces with gross weight due to fuel burn – less weight requires less lift resulting in less drag, therefore thrust can be reduced
106
What happens to SFC as altitude is gained?
It decreases
107
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
108
Optimum altitude is a function of?
SFC and TAS
109
Does temperature affect optimum flight level?
No as it has an equal effect on fuel flow and TAS
110
Specific air range formula is?
SAR = FF (Fuel flow) / TAS
111
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.
112
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
113
Factors affecting the stall speed:
```
weight
power
flap
loading
ice/damage
```
114
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:
o A forward C of G decreases Vmca o An aft C of G increases Vmca
115
What is the function of an Inverter?
Convert DC to AC.
116
What is the function of a Rectifier?
Convert AC to DC
117
What do CSD's (Constant Speed Drives) do?
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.
118
What is RVSM?
Reduced Vertical Separation Minimum.
Above FL290 RVSM procedures apply to operators approved in RVSM procedures
119
Name the 5 main modes of GPWS:
Excessive rate of descent "sink rate"
Excessive terrain closure "terrain terrain"
Excessive altitude loss after take off "sink rate pull up"
Aircraft too low without gear or flap (shallow flight path)
"too low, terrain"
ILS deviation (1.3 dots below glide-slope)
"glide slope"
120
What are the inputs to GPWS?
```
Radio altimeter
ILS receiver
Barometric pressure sensing
Flap & gear position
Airspeed
```
121
What is the operating envelope of GPWS?
2450ft AGL to 30ft AGL (radio altimeter)
122
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)
123
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.
124
Explain how TCAS interrogates intruder aircraft:
TCAS uses transponder signals from other aircraft to determine relative positions
125
State the TCAS symbology:
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 - (Within 15 - 35 sec’s action required)
126
With TCAS when given a traffic advisory what would the pilots display indicate to him?
A relative indication of a solid red square / the aircraft’s altitude / if it is climbing or descending (an arrow) and an aural “TRAFFIC TRAFFIC’
127
What is GPS?
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.
128
How does GPS work?
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.
129
To aquire accurate positions using GPS how many satellites are required?
4 minimum
130
Differential GPS is:
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 turn correct themselves, computing a more ‘relative position between an aircraft receiver and a ground based receiver for them to track to.
131
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
132
GDOP is:
Geometry dilution of precision – the angle of the satellites relative to the aircraft, larger angles provide better accuracy of position and distance
133
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
134
Explain FANS:
Future Air Navigation System – Implementation of satellite technology for improved communication and navigation tracking surveillance.
135
What is ETOPS?
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). It 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 and B767 on 180 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.
136
What is a 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.
137
What is a 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.
138
What is a Rhumb Line?
A line drawn on the centre of the earth which cuts each meridian at the same angle.
139
What is a Parallel of latitude?
Small circles joining points of equal latitude – except equator, which is a great circle
All are rhumb lines
Lie east to west
140
What is a Meridian of longitude?
Semi-great circles passing thru the poles
141
What is a 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)
142
What is an Isogonal?
line joining points of equal variation
143
What is a 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)
144
What is a 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 x cos lat
145
What is Earth Convergency?
The angle of inclination between two meridians at any given latitude
Earth convergency = change in long x sin mean lat
146
What is the speed of the Rotation of Earth?
900kts at equator or
| 900 x cos lat = speed at a given latitude
147
What is a 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
148
What is a 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
Rhumb 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.
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What is a 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
150
What is Orthomorphism?
All chart used for nav must have these two qualities.
1. The scale on the chart must be correct to the scale nearby (equal scale expansion)
2. Parallels and meridians must cross at right angles.
Time to Arc
1 degree ofarc = 4min
15’ of arc = 1 min
1’ of arc = 4 sec.
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1/60 Question: -9 degrees off track after travelling 15nm, how far off track?
- 2.25nm
- 1 degree off in 60nm = 1nm off track
- 9 degrees off in 60nm = 9nm / 4 (60/15) = 2.25
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Datum for GNSS approach?
* A datum is a model of the earth that is used in mapping. The datum consists of a series of numbers that define the shape and size of the ellipsoid and it's orientation in space. A datum is chosen to give the best possible fit to the true shape of the Earth.
* Reference datum used by ICAO signatories is WGS 84
* Problems may occur if a different reference datum is used
* WGS 84 is absolutely a requirement
153
Maximum holding speed below FL140?
- 230kt, or
| - 170kts for holding where the approach is limited to Cat A and B aircraft
154
What it the maximum holding speed between FL140 and FL200?
- 240kts
155
What is the maximum holding speed above FL200?
- 265kts
156
What is BC on a weather forecast:
- Patches
157
What happens to buffet boundaries as a jet gets lighter as it burns fuel?
- Buffet boundaries get further apart
| - As fuel burns off, Jet can fly higher
158
What is a hydraulic accumulator?
- A hydraulic accumulator is a PRESSURE STORAGE reservoir in which a non-compressible hydraulic fluid is held under pressure that is applied by an external source. The external source can be a spring, a raised weight, or a compressed gas.
- Not to be confused with a hydraulic fluid resevoir
159
MDA on a non-precision approach is never lower than?
MDH:
- 250ft LLZ
- 250ft VOR/DME
