Term
| What is the function of the ALIGN position of the IRU Mode Selector? |
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Definition
Initiates alignment
Removes sensor errors when selected from NAV mode |
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Term
When is full alignment of the IRS required?
How long does it take? |
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Definition
When the time from the last full alignment to the next expected arrival time exceeds 18 hours
10 minutes |
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Term
| How do you accomplish a fast alignment of the IRS? |
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Definition
Airplane must be parked
Position the selectors to ALIGN
Enter present position
Reposition the selectors to NAV
Takes 30 seconds
Fast alignment can be accomplished without entering present position. However, greater navigational accuracy is attained by entering present position |
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Term
| What does the IRS ON Battery (BAT) Light mean, when displayed on the Overhead Maintenance Panel? |
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Definition
The navigation mode is inoperative for the remainder of the flight
Attitude information can be obtained by moving the selector to ATT |
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Term
| How are the IRSs affected in the event of a loss of AC power? |
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Definition
Powered by DC backup power via the APU Hot Battery Bus
Center only runs for 5 minutes |
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Term
| How many FMS’s and how many FMCs are there? |
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Definition
One FMS (flight management system)
Two FMCs (flight management computers L and R) |
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Term
| What determines present position of the airplane, and where on the ND is it displayed? |
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Definition
FMC
Tip of the white triangle |
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Term
| How is FMC position updated? |
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Definition
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Term
| What does a “VD” FMC radio position update status indicate and where is it displayed? |
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Definition
VOR and its collocated DME
Lower right hand corner of the ND, in green |
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Term
| What is lost during alternate navigation? |
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Definition
| LNAV, VNAV, autothrottles |
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Term
| What CDU pages are available during Alternate Navigation? |
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Definition
ALTERNATE NAVIGATION
LEGS, PROGRESS, RADIO |
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Term
| Which waypoints are referenced and displayed in magnetic and which are displayed in true on the alternate navigation LEGS pages? |
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Definition
Only the active waypoint is referenced to magnetic north.
All subsequent waypoint courses are true courses. |
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Term
| When does the heading reference change to true north? |
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Definition
At 82N (or north of 70N between 80W and 130W)
At 82S (or south of 60 S between 120E and 160 E) |
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Term
| When would you ever select the “TRUE” position on the Heading Reference switch? |
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Definition
| For autopilot operations in high latitudes using a roll mode other than LNAV |
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Term
| When does the FMS enter polar operation conditions? |
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Definition
| When the FMC calculated airplane position passes north of 84 north or south of 84 south (FMCs revert to split IRS) |
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