FMS and Navigation Flashcards
FMS and Navigation
Which Air Data Module (ADM) sends its info directly to the IFSD ?
The CENTER ADM.
FMS and Navigation
If voted ADRS Air data is invalid, what is the next backup system ?
Backup Airspeed and Backup altitude information is sent to the PFDs.
Backup airspeed is based on AoA and data from the IRS.
Backup altitude is provided by GPS data.
FMS and Navigation
If Backup Airspeed and Altitude are invalid, what is the next backup ?
ISFD altitude and airspeed will be displayed on both PFDs.
FMS and Navigation
Can the IRS be realigned in flight ?
Yes, if GPS data is available.
FMS and Navigation
What is the IRS composed of ?
2 IRS each containing :
- 1 IRU (Inertial Reference Unit)
- 1 AHRU (Attitude Heading Reference Unit)
FMS and Navigation
In case of failure of the 3 FMCs, how can navigation be achieved ?
Through the Alternate Navigation feature of the TCPs.
It is accessed by pressing the NAV button on the TCP.
Alternate navigation data is displayed on the TCPs and the ISFD.
FMS and Navigation
What is ANP : Actual Navigation Performance ?
ANP is the FMS position accuracy.
It can be visualized as a circle that contains all possible computed aircraft positions.
The aircraft is assumed to be within this circle 95% of the time.
FMS and Navigation
When starting a descent before the computed TOD, by using the “descend now” prompt, what initial rate of descent will be commanded ?
Approximately 1250 ft/min.
The DESCEND NOW prompt is available until 50 NM from the TOD.
FMS and Navigation
When will the VNAV mode switch from VNAV PATH to VNAV SPD during descent ?
If more than 150 ft above or below the VNAV Path.
FMS and Navigation
When is ILS autotuning inhibited ?
For 10 minutes after take-off and during manual tuning.
FMS and Navigation
What is the difference between OPT and RCMD FLs on the VNAV CRZ page ?
The RCMD (Recommended) speed takes into account forecast winds and temperatures at cruise altitudes. The FMC evaluates FLs from 9000 feet below the current CRZ FL up to the max FL.
