Auto Flight Flashcards
The FMS can calculate aircraft position using 3 different methods, what are they?
Mix IRS Position - the average position of the 3 IRSs calculated by accelerometers
Radio - Position is an exact position based on a fix I.e VOR/VOR VOR/DME
GPS - Position is an exact position based on 2 independent GPS satellites
What navigation mode does the aircraft FM system use as standard?
The FM system will generally use a Mix IRS/GPS position
Then a Mix IRS/Radio position
Then a Mix IRS only (pure inertial)
In flight the FM position approaches the GPS/Radio position over the Mix IRS position at a rate depending on aircraft altitude (this is due to accelerometer BIAS)
What is meant by the term BIAS with regards to aircraft position?
Each FMGC computes a vector from its Mix IRS position to the GPS/Radio position. This is known as BIAS. If an FMGC loses its GPS/Radio position it memorises the BIAS and uses this to compute FM position until Radio or GPS is restored.
When will the energy circle display on the ND and what does it mean?
The energy circle (green arc) appear on the ND in HDG or TRK and indicates the required distance to complete a landing. Must be <180nm to destination
How does the FMS detect an engine out condition?
- Engine master switch off
- Engine N2 below IDLE
- One TL angle <5deg and other <22deg
- FADEC detects an engine fault
If EO CLR is pressed on the PERF page by mistake what are the implications?
All Single engine calculations are lost and can’t be recovered. All predictions are now based on 2 engine and therefore incorrect
What is ENG OUT REC MAX?
Based on aircraft weight and is the maximum altitude we can fly with MCT set and maintain level flight with 0.3g buffet margin
How many channels does the AUTOTHRUST have?
2, 1 per FMGC.
If ATHR fails in flight, try switching AP and reengaging
When does THRUST LOCK occur?
When THR levers are in CLB or MCT and the A/THR pb is pressed or ATHR disconnect due to failure
Thrust is kept at previous value and THR levers must be moved to match thrust
What is RETARD MODE and when does it activate?
During an autoland thrust is automatically brought to IDLE at 40ft
RETARD is called out at 10ft
During a manual landing is 20ft
How does Groundspeed mini work?
Will keep A/C energy above a minimum level for wind/atmospheric changes
Managed speed target constantly changes to adjust for wind Vapp = VLS +1/3rd headwind or Min VLS +5
How many FACs are there and what functions do they perform?
2 FACs
- Yaw function
- Low energy warning
- Reactive windshear detection
- Flight envelope calculation
