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Flashcards in FMS Deck (32):
1

What's in a Nav DB?

Nav DB is read only so can't change the data but you can insert info/waypoints. But the inserts now become user defined content which are not saved if system is updated.

•SID/STAR/approach
• Waypoints
• Airways
• Runways
• Airports
• NAV aids - VOR/DME/NDB/ILS
• Holding patterns
• Company routes

2

What's in a perf DB?

• V speeds (climb/enroute/descent spds)
• A/C masses
• Flight envelop
• Drag characteristics
• Fuel Flow (FF) - for clean and diff configurations
• Cost index (CI)
• Optimum and max altitude

Perf DB updated when necessary

3

FMC CDU pages in order are....

Page
1: Ident
2. POS init page where insert ILS/IRS data
3. Route (RTE)
4. Perf initialisation

4

What Nav aids will the FMS rely on to get a fixed position, in order of priority?

• GPS
• IRS/INS
• DME/DME
• VOR/DME
• VOR/VOR
• LOC

5

FMS XTK is?

The abeam distance error to the left or right from the desired flight plan leg to the aircraft position

6

ABEAM:

An aircraft is "abeam" a fix, point, or object when that fix, point or object is approx 90˚ to the right or left of the A/C track.

Abeam indicates a general position rather an a precise point.

7

What is FMS?

FMS provides a centralised interface to:

• mange auto nav/plan a route

• optimise flight perf & fuel efficiency

• generate info on flight deck displays.

8

Due to the harsh aviation environment, how are CPUs stored on an A/C?

The CPUs are hard wired into shock proof casings with ruggedised data connections. These are known as LRUs.

9

What are software standards?

The strictness of requirement on a system depending on the effect of that system after failure in flight.

E.g. Cabin px failure would have more of a catastrophic effect in flight than a warning light having blown a fuse in the cockpit.

10

What are the software standards Levels?

Level A:
Catastrophic (e.g. Fly by wire).
Probability 1x(10-9). 10 to the neg 9

Level B:
Hazardous (e.g. FMS).
Probability 1x10-7

Level C:
Major (e.g. ATSU)
Probability 1x10-3

Level D:
Minor
Probability 1x10-3

Level E:
No effect
No max probability

11

What does an FMS comprise of (parts)?

• FMC
• CDU
Together they for the FMCS
(Flight management computer system)

• symbol generator
• electronic flight instrument system (EFIS)
• A/T and FCC (flight control computer)

12

FMS comprises of a number of independent systems, these include?

• FMC (flight management computer)

• The autopilot/flight director system (AFDS)

• The auto throttle

• The inertial ref system (IRS) or ADIRS, GPSADIRS if fitted

13

What must be inputted into the FMS to retrieve LNAV (lateral navigation)?

Route info

Info is inputted from the "scratchpad"

14

What must be inputted into into the FMC to produce the optimum VNAV (vertical navigation)?

ZFW, OAT, Cost index, Winds, Fuel


Info is inputted from the "scratchpad"

15

FMS has 2 main databases, what are they?

• Navigational

• Performance

16

What info does a (FMS) Nav database contain?

• charts
• approach plates
• airport RW data
• flight routes/plans and nav aid locations


17

What must be done to a Nav database after a time period?

Must be updated every 28 days.

If fly with an outdated Nav DB, you will need CAA authority to fly now despite already being in the air!

18

What info is contained in a (FMS) performance database?

• contains info normally found in A/C perf manual e.g. V speed, MTOM, flight envelope etc.


• It is used to calc optimum pitch, speed and thrust control.

19

What other systems input into a FMS?

• ADC (airspeed, OAT, altitude)
• Air/ground sensing logic (sense when air borne)
• clock time
• fuel sensors
• IRS

20

How is FMS controlled?

Via the MCP (mode control panel)

When SPD/LNAV/VNAV is in use, this is known as managed flight.


There are 2 types of control:
Tactical: immediate commands e.g. Turn left 30˚ now

Strategic: overall guidance e.g. Programming an entire LNAV profile.

21

Aircraft position is inputted at the start of the flight and is continually updated using info from IRS, GPS and Nav aids. Rad Nav aids are auto selected by the FMC with its own NAV frequencies.

It uses the following priority for position determination:

• 2 or more DME stations
• DME/VOR
• VOR/VOR
• VOR/VOR
• Localiser and co-located DME

22

POS REF page shows....

The inputs that the FMC is using to determine it's position.


An algorithm is then used to find the final position.

23

FMS Setup:

Normally both FMCS are working together with a designated master and slave.

There is a switch that can be used to choose just one FMC to operate if there is a malfunction with the other.

24

(FMS setup):

Single mode: allows all EFIS displays and CDUs to operate if there is one FMC failure.

Back up mode:
Allows a malfunctioning FMC to still be used to produce very select info.

25

The FMS flight plan or LEG page displays?

Speed (IAS)
Distance
Track

26

The purpose of the FMS is to provide....

Continuous automatic nav guidance and performance management

27

FMS designed with VNAV capability coupled with autopilot, the FMS command output can be?

• A flight path angle
• A speed target

VNAV coupled with autopilot will produce command in pitch.

28

Concerning FMS, the parameters used to work out the vertical flight path profile are?

• ZFW
• Cost index
• Fuel quantity

29

The FMS vertical navigation management is generally performed based on:

The inputs from the ADC's barometric sensors (baro altitude)

30

What are the typical content of the FMC nav DB?

• ref data for airport (4 letter ICAO Identifier)
• VOR/DME station data (3 letter ICAO identifier)
• Way point data (5 letter ICAO Identifier)
• STAR data
• SID data
• Holding patterns
• Airport RW data
• NDB stations (alphabetic ICAO identifier)
• Company flight plan routes

31

What are the typical content of the FMC perf DB?

• V1, VR and V2 spds
• A/C drag
• Engine thrust characteristics
• Max and optimum operating altitudes
• Speeds for max and optimum climbs, LRC, MMR and holding
• MZFM, MTOM, MLM
• FF parameters
• A/C flight envelope

32

How often is a nav DB updated?

Every 28 days.

If flying overnight and past expiry, previous DB valid for up to 12hrs longer in these cases.