FMS Flashcards
FMS
3d flight management system that calculates a 4d flight trajectory
CDU
control display unit
1 for captain 1 for FO, sometimes a third
FMC
flight management computer
2, one for each CDU, connected as a backup up to other CDU
X-talk bus- connects both FMC so they can communicate
Duel mode
normal operation
each CDU connected to its own FMC
FMCs communicate via x-talk bus
info entered on either side will update eon both
single mode
one FMC failed
both CDUs on one FMC
info can still be entered on either side
may be limitations on AP usage and EFIS
NAV displays may need the same mode and range set
independent mode
X-talk bus failed
FMCs cant communicate
entering on CDU1 only FMC1 would receive it
need to enter information on both sides separately
FMS inputs
pilot clock database GPS IRS ADC configuration fuel air ground logic switch FWS CDU NAV radios
FMS outputs
autopilot
auto thrust
HUD
EFIS
navigation database
SID's- standard instrument approaches STAR's- standard arrivals airways way points airports approaches runways company routes
valid over 28 day period
ways to enter way points
lat and long
Wpt name
nav aid ident
ICAO airport code
performance data base
fuel parameters drag parameters engine parameters speeds one engine inoperative data
it can account for engine failure
can not account for non-standard configuration
FMS position calculation
mixes various sources of position to find most likely position sources: -VOR,DME , localiser on some - GPS -IRS
priority of sources
GPS>DME>VOR>IRS
initialising the fms
1) who am I? IDENT- aircraft type/ engine type
2) where am I? pos init- position info
3) where am I going? route- route info
4) how do I get there? performance
FMS functions: LEGS page
waypoints tracks distances predicted speed predicted altitude speed constraints altitude constraints
FMS functions:LNAV
lateral navigation
connects auto pilot and FMS
FMS tells AP to fly: headings & bank angles to achieve flight planned route
FMS functions: VNAV
vertical navigation
FMS gives AP: speed target or vertical speed target vertical profile calculated using: barometric alt ZFW fuel quantity cost index
FMS functions: X-trk
works out perpendicular distance from flight planned route
route will be a great circle
FMS 1 says 0 X-trk error
FMS 2 says 4R error
what can you say?
at least one is wrong
FMS functions: lateral offset
allows pilot to fly a constant lateral offset left or right of route
may be used to avoid collisions if mistake was made that you were on same FL as others in other direction
FMS functions: RTA
required time of arrival
pilot enters desired time of arrival at a waypoint or destination
FMS then calculates CAS/Mach no. that will achieve it
FMS functions: temperature corrections
not all FMS’s can do this
non-precision approach check heights can be corrected at very low temps automatically
FMS functions: approaches
FSM's approved to fly non precision approaches: VOR loc only RNAV NDB
FMS functions: fuel prediction
predicts fuel remains at each waypoint and destination
uses wind entered at each waypoint OR current wind extrapolated over the remaining flight
AIDS FUEL MANAGEMENT
CANNOT use for FUEL PLANNING
dead reckoning mode
back up position mode
if normal position sources are lost the FMS provides position guess with speed distance time calc
Boeing fuel philosophy
calculated fuel- calc how much has been used by each engine. subtracts from starting
totaliser fuel- fuel measured in each tank then added to get total
calculated should = totaliser
Airbus fuel philosophy
totaliser fuel- measured in each tank then added for a total
used fuel- keeps track of how much each engine has used
PILOT then deducts used from starting to compare to the totaliser
