FLIGHT MANAGEMENT AND NAVIGATION Flashcards
What information do the IRSs provide?
Attitude, heading and position information (including groundspeed)
Are they (IRSs) dependent on, or independent of, external navigation aids?
Independent
How is the GPS activated and what does it provide data for?
GPS is always on when aircraft is powered
provides an accurate aircraft geographical position to the FMC
Clock
Transponder
With the FMC SOURCE select switch in NORMAL, which FMC is primary and what does it control?
L FMC is PRIMARY and provides information for CDUs and autothrottles
Describe the criteria for airports included in the nav database`
5000x100ft runway and IFR Approach
When using the Autothrottle system, how are reference thrust limits calculated, and how is thrust equalization maintained?
reference thrust limits calculated by the FMC
thrust equalization maintained through the electronic engine controls (EEC)
How are the FMCs operated?
Uses flight plan information entered by the Crew into the MCDU
Left is master
Left shares data with the Right Controls the A/T
Provides information to the Display Units
Where do the FMCs receive their inertial data from?
The IRS through the ADIRU from the corresponding side (ex left ADIRU to FMC 1). 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 does the FMC use to determine position?
In this order:
GPS
—>IRS
——->Ground based navaids (except for ADF)
If GPS data is not available, how does the FMC calculate the present position?
IRS then ground based navaids If GPS data is not available, the FMC calculates the present position based on IRS data.
FMC position updates from navigation sensor positions are used in what priority order?
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
How does the FMC calculate a descent path during a VNAV PTH descent?
Starts at the bottom of descent and works backward, taking into account altitude and speed constraints and restraints for an idle descent, factoring in winds and anti ice
How can you further reduce a derated takeoff?
Select a derated setting in FMC and use an assumed temp to further derate
What is the lateral navigation (LNAV) intercept criteria?
Inside 3 miles it will automatically intercept
Outside 3nm you must be:
- Intercept angle less than 90deg to the course with a valid TO waypoint
When does IRS position and ground speed information become available and up to how long could it take
after it is aligned
Alignment time varies from 5 to 17 minutes depending on the aircraft latitude
High latitude could take up to 17 minutes
