What is the FMGS and what does it do?
- Flight Management Guidance System
A) Guidance. Controls autopilot, autothrust and FDs
B) Management. Provides information on flight [think about pages of MCDU] (e.g flight plan, fuel predict, nav guidance etc)
What are the components of the FMGS?
- 2 x MCDU
- 2 x FMGC
- 1 x FCU (on glareshield)
- 2 x FAC
- Flight controls
FMGC1 and FMGC2 have two main functions. What are they?
- Flight Management
a) controls navigation
b) auto tuning of nav aids
c) flight planning
d) perf - Flight Guidance
a) Autopilot
b) Flight Directors
c) Auto thrust
What are the 4 operational modes of the FMGC?
- Dual mode
a) Each FMGC separately perform their own computations and exchange data on a crosstalk bus
b) data inserted into MCDU updates both FMGCs - Independent modei) where there’s a mismatch of data between the two FMGCs
a) Each FMGC works independently (stop talking to each other) and control their own onside peripherals
b) An entry on MCDU1 will only send info to its own FMGC1
c) summary - no cross talking - Single mode
a) when an FMGC fails
b) remaining FMGC controls all peripherals
c) live FMGC updates both MCDUs - Back-up Nav mode
a) if both FMGCs fail
b) pilots must manually activate this mode
FMA. What’s the difference between ALT (blue) and ALT (magenta) during a climb
- ALT (blue) if targeting FCU selected altitude
- ALT (magenta) if it is targeting a level off constraint
Can you be in a managed vertical mode if not already in a managed lateral mode?
No
Does OP CLMB or OP DES take into account constraints?
No (they are not taken into account in selected Modes)
What does the EXP pb do on the FCU?
Will climb at Green dot (ie best L/D). Will descend at 340kts
How does the FMGC calculate where it is?
- Gathers data from
a) IRS1
b) IRS2
c) IRS3 (known as the “Mix IRS”)
[GPIRS data - hybrid of IRS and GPS data]
d) GPIRS1
e) GPIRS2
f) GPIRS3
(The best GPIRS is picked and is used to refine the Mix IRS position)
All going well- “GPS PRIMARY” will be shown in MCDU (PROG page). Means all usual navigation performance requirements are met
Additional position determination via:
- DME/DME
- VOR/DME
- Localiser signals
NAV accuracy limits- in en route area, terminal area, approach area with GPS and approach area without GPS
En route = 2.0nm
Terminal area = 1.0nm
Approach area (without GPS) = 0.5nm
Approach area (with GPS) = 0.3nm
If outside of limits - PROG page will show accuracy as “LOW”
IRS Alignment key facts:
- IRS alignment must only be done on the ground
- Takes around 10 mins to align (time remaining shown on E/WD)
- Alignment is complete when pilot enters a company route or the origin-destination field in MCDU
- Fast alignment (quickly switch IRS1-3 off and on). Used for stopovers. Takes 30 seconds
PFD - 5 FMA columns. What are they from left to right?
- Auto thrust mode
- Vertical mode
- Lateral mode
- Approach capabilities
- Autopilot / flight director / autothrust status
Flight Directors key facts
Normal
- FD1 on PFD1 is controlled by FMGC1
- FD2 on PFD2 is controlled by FMGC2
Failure of an FD or FMGC
- Remaining FD is supplied on both PFDs
- FMA indication “1 FD 1” (ie FD2 not engaged)
When are the flight directors removed from view?
- Pitch (above 25 degrees nose up)
- Pitch (below 13 degrees nose down)
- Bank angle (over 45 degrees)
Autopilot. Which computers receive signals from FCU / FMGC to move control surfaces?
- They are sent to the various control surface computers as follows:a) 2 x FAC (for rudder and yaw damper)
b) 2 x ELAC (for elevator and aileron)
c) 3 x SEC (for spoiler and standby elevator)
d) 1 x Brake and Steering Control Unit (BCSU) - for control of nosewheel on the ground
Autopilot AP1 and AP2 facts
Normal
- AP1 Only selected (run by FMGC1)
- AP2 only selected (run by FMGC2)
- AP1 and AP2 selected (FMGC1 is master and FMGC2 in standby)
What happens when press red button on control stick - turn autopilot off
- Master Warning light (3 seconds)
- Cavalry charge sound
- ECAM message
(If press AP red pb again - it switches off the aural sounds / messages)
Methods of turning off AP?
- pb on side stick
- pbs on FCU
- Moving the THS wheels
- Pressing rudder pedals
Abnormal ways AP disconnected?
- Over speed
- Excess AOA
- Bank angle above 45 degrees
A/THR key points
- Active after take off when select CLB on thrust lever (prior to it is white and armed when select FLEX or TOGA)
- Armed is blue / active is white on FMA (column 5)
- Process - FMGC calculates thrust required - sends info to FADEC - FADEC controls FF for desired thrust
- The thrust lever simply acts as an upper thrust limit
What are the 3 Auto Thrust modes?
- THRUST Mode (sets engine thrust to a specific thrust level)
- SPEED / MACH MODE
- RETARD Mode (available only during autoland. 40ft - idle set automatically. 10ft - retard callout reminded pilot to set idle thrust)
What is thrust lock?
- If error with A/THR - ECAM “THR LK” appears
- Thrust is locked at its current setting and will not change
- Exit lock by taking manual control of thrust levers by moving out of the CLB detent
What’s the difference between FAIL OPERATIONAL and FAIL PASSIVE?
TBC
In a climb (managed mode) how is an upcoming constraint at FL200 shown on the FMA? What happens when FL200 is reached?
- ALT (Magenta)
- FL200 (Magenta) on altitude tape
When reached:
- Auto thrust changes to SPEED
- “ALT CSTR *”
- “ALR CSTR”
