Flight Management, Navigation

Question 1

What information is displayed by the IRS on the overhead panel?

Answer 1

Track, groundspeed, present position, wind, or heading, as controlled by display selectors or keyboard.
(Directions are referenced to TRUE north)

Question 2

What entries are required to complete IRS alignment?

Answer 2

• Enter present position on the IRS keypad

- FMS CDU

Question 3

Do IRU’s load shed when on standby power?

Answer 3

Yes, but at least one IRU remains powered on all aircraft

Question 4

What is the meaning of a steady illuminated white ALIGN light on the IRS?

Answer 4

The related IRS is operating in the ALIGN mode, the initial ATT mode, or the shutdown cycle

Question 5

What is the meaning of a flashing white ALIGN light on the IRS?

Answer 5

Alignment cannot be completed due to IRS detection of:

• significant difference between previous and entered positions or an unreasonable present position entry.
• no present position entry.
• aircraft movement detected during alignment process.

Question 6

What does it mean if the ALIGN light on the IRS panel is extinguished?

Answer 6

• IRS not in ALIGN mode

- With mode selector in NAV, alignment is complete, and all IRS information is available.

Question 7

How much time is required for full and fast IRS alignment?

Answer 7

Full alignment - 10 minutes

Fast realignment - 30 seconds

Question 8

What does an amber IRS DC FAIL light mean?

Answer 8

DC backup power for the related IRS has failed.

Question 9

What does an amber IRS fault light mean?

Answer 9

A system fault affecting the related IRS ATT and/or NAV modes has been detected.

Question 10

How is the knob used on the IRS mode selectors?

Answer 10

Rotate to control mode of related IRS, must be pulled out to move from NAV position.

Question 11

On the IRS mode selectors, what does OFF mode do?

Answer 11

• Alignment is lost
• ALIGN light illuminates for 30 seconds as system goes through a shutdown sequence
• Realignment requires 10 minutes while parked and entry of present position (lat/long)

Question 12

On the IRS mode selectors, what does ALIGN mode do?

Answer 12

• Initiates alignment when parked

- Initiates a quick alignment if selected when the system is in the navigation mode

Question 13

On the IRS mode selectors, what does NAV mode do?

Answer 13

• Normal operational mode
• permits system to enter NAV mode after completing alignment
• Initiates a 10 min alignment if selected from OFF.

Question 14

On the IRS mode selectors, what does ATT mode do?

Answer 14

• Provides only attitude and heading information
• Position and ground speed information lost until system realigned on the ground
• If selected airborne, ALIGN light illuminates for 30sec while system senses local level (requires level flight)
• Mag heading input required to initialize heading output
• Selector must be cycled through OFF to re-enter ALIGN or NAV mode.

Question 15

When should the IRS ALIGN lights be allowed to extinguish?

Answer 15

Prior to either accomplishing a full alignment or selecting the battery switch to OFF.