01/18/23 Flt Management, Nav Flashcards
Is IRS output information independent of or reliant upon external navigation aids?
Independent,
IRS outputs are independent of external navigation aids.
How long does IRS alignment take?
5-17 minutes
When does the ALIGN (white) illuminate steady on the IRS panel?
- Align Mode
- initial ATT mode
- shutdown cycle
What does a flashing ALIGN (white) on the IRS panel during preflight indicate?
No position
Wrong position
Without AC power, how long can the IRSs operate? What light(s) will you see?
ON DC caution light illuminates, as well as MASTER CAUTION and IRS lights.
Backup DC power to the right IRS is automatically terminated if AC power is not restored within five minutes.
The Switched Battery Bus will continue to supply power to the Left IRS as long as it’s powered. (60 minutes?)
What does a VERIFY POSITION FMC scratchpad message indicate?
If the latitude/longitude position is not within 4 nm of the origin airport, the CDU scratchpad message VERIFY POSITION is displayed.
How many GPS receivers are installed?
2
Two GPS receivers receive GPS satellite positioning signals from the GPS antennas.
Are the FMCs independent of one another? Do they compare information?
Yes Independent, Yes the compare
The left FMC is normally primary with the right FMC operating as a backup. The right FMC operates in synchronization with the left. The maps display composite information from both FMCs.
Where do the FMCs receive their inertial data from?
Usually, the FMCs receive inertial data from their on-side ADIRU (left ADIRU to FMC 1 and right ADIRU to FMC 2). If the on-side ADIRU malfunctions or it is in the ATT or ALIGN mode, the FMC uses the data from the other ADIRU.
What’s the criteria for airports to be included in the nav database?
- All destinations, alternates and frequently used charter and maintenance locations included.
- Paved runway 5000’ x 100’ with an approach
How can takeoff thrust be derated?
Fixed derates and Assumed Temperature also can be selected on the N1 LIMIT page.
What sources do the FMCs use to determine position? In what order?
The FMC determines present position from the GPS, and IRS navigation radios.
FMC position updates from navigation sensor positions are used in the following priority order:
• GPS
• two or more DME stations
• one VOR with a co-located DME
• one localizer and co-located DME
• one localizer
NOTE: DME updating is defaulted OFF.
What criteria must be met for LNAV engagement?
LNAV provides steering commands to the next waypoint. If selected:
• LNAV engages when laterally within 3 nm of the active route leg
• if outside of 3 nm of the active route leg, LNAV engages if on an intercept heading of 90° or less and the intercept will occur before the active waypoint
FMC LNAV guidance normally provides geodetic paths between waypoints.
How does the FMC calculate a descent path during a VNAV PTH descent?
The descent path is computed prior to the top of descent to the end of descent (E/D) prior to a discontinuity and is then frozen unless the pilot executes a major edit to the flight plan, such as a:
• lateral route modification
• change in a speed or altitude constraint, or
• change to the descent speed in the FMC
The path is not adjusted or recomputed during descent
The descent path calculation projects upward from the end of descent (E/D) point to the
cruise altitude. The FMC calculates a descent path based on airspeed restrictions, altitude
restrictions and the E/D point. The E/D point is shown on the MAP as a green open circle
with the label E/D and is the last of the following that is not proceeded by a lateral
discontinuity:
- the runway threshold for approaches with a runway waypoint on the active RTE
LEGS page, or
- the missed approach point for approaches not showing a runway waypoint on the
active RTE LEGS page, or
- the last descent waypoint, or
- the lowest “at” altitude if no arrival procedure is entered
