IRS

Question 1

How do you select the IRU mode selector from NAV

Answer 1

• Pull and rotate switch to move from NAV
• Indented at NAV

Question 2

What is the function of the ALIGN position of the IRU Mode selector

Answer 2

Starts the alignment process
- moving through ALIGN to NAV will start the alignment process and go into Nav when done

Question 3

How long does it take to fully align the IRS

Answer 3

10 minutes

Question 4

When is full alignment of the IRS required

Answer 4

• 18 hours
• or last full alignment to arrival is 18 hours

Question 5

How do you accomplish a fast alignment?

Answer 5

SP.11.11

1. IRS mode selectors - ALign
2. CDU - Set
   Enter position on SET IRS POSITION line
3. IRS Mode selectors. - NAV

Question 6

What does IRS ON BAT light mean when displayed on the overhead maintenance panel

Answer 6

IRS operating on backup power (APU hot battery bus)

Question 7

Explain what happens when alignment of the IRS is lost in flight

Answer 7

• if complete IRS lost in flight pilot will need to reference standby attitude indicator for Roll and pitch and the Standby Magnetic compass for heading reference
• if NAV mode fails non-normal procedure will provide guidance to select IRU with fault to ATT mode to attempt to restore minimum operation
• once att selected cannot use NAV until full alignment on ground

Question 8

What happens if the center IRU is operating on DC power

Answer 8

C IRU operates of 5 min on DC power then shuts down