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Flashcards in Flight Management, Navigation. Deck (16):

What is the directional reference for IRS track, wind direction and heading displays on the IRS Mode Selector Panel?

TRUE (Track, wind direction and heading)


What crew input is required before the IRS can complete alignment and enter NAV mode?

Present Position.


Where is present position normally entered during alignment?



Where may present position be entered if the FMS CDU's are unavailable?

IRS mode selector keyboard.


Approximately how much time will a full IRS preflight alignment take?

10 minutes


What are the causes of a flashing ALIGN light during the initial alignment process?

Alignment cant be completed because:

Significant diference between previous and entered positions, or an unreasonable present position entry.

No present position entry.


What is the meaning of an illuminated ON DC light?

- Normal AC power for the related IRS has failed and the IRS is operating on DC backup power from the hot battery bus (AC power not normal).

-If on the ground, the ground call horn in the nose wheel well sounds, providing an alert that a battery drain condition exists.

Momentary illumination is normal during alignment self test.


What is the normal source of electrical power for the IRU's?

Normal AC power form the left and right systems.


What is the meaning of an illuminated "DC FAIL" light?

DC backup power is lost and AC power is being used.


What is the alternate power source for the IRU's

Main aircraft battery (DC)


Which IRU's remain powered after 5 minutes when AC power is lost on the aircraft?

The Right IRU


What happens when AC power is removed from the aircraft prior to turning off the IRU's while on the ground?

ON DC light illuminates and a horn in the nose wheel well illuminates.


Describe the function of the IRS ATTITUDE mode.

If alignment is lost in flight, navigation mode is inoperative for the remainder of the flight. If selected to ATT, the IRU enteres the Align mode for 30 seconds during which the airplane should stay in strait and level flight. This re-levels the system and provides attitude displays on the ADI. Altitude errors may occur. Heading information is provided if a heading entry is made on the MCDU POS INIT page or IRS mode select panel.


How is heading information updated when an IRU is in the ATTITUDE mode?

Enter the aircraft heading (obtained from the compass) on the MCDU POS INIT page.


How many VOR radios are installed?



How many ILS receivers are installed and how are they tuned?

Three, controlled by a single control panel on the aft isle stand.