Flight Management, Navigation

Question 1

Recall what information is displayed by the IRS (Inertial
Reference System) on the overhead panel.

Answer 1

Displays track, groundspeed, present position, wind or
heading as controlled by display selectors or keyboard.

Note: Directions are referenced to true north.

Question 2

Recall the entry required to complete IRS alignment.
(2 methods of entry)

Answer 2

• Enter present position using the IRS MODE SEL keypad
• Enter present position in the FMS MCDU “SET IRS POS”
  boxes on the POS INIT page.

Question 3

Recall the IRU(s) load shed after 5 minutes when the
aircraft is operating on standby power.

Note: At least one IRU remains powered on all aircraft

Question 4

Describe the meaning of both steady and flashing IRS
ALIGN lights

Answer 4

• Illuminated (white) –
• Steady – The related IRS is operating in the:

ALIGN mode or
The initial ATT mode or
The shutdown cycle

• Flashing – Alignment cannot be completed due to IRS
  detection of:
  A significant difference between the previous position
  and last
  entered position or
  An unreasonable present position entry or
  No present position entry or
  Aircraft movement was detected during the alignment
  process.
• Extinguished –

The IRS is not in the ALIGN mode

or

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

Question 5

Recall the time required for IRS alignment:

Answer 5

• Full alignment: 10 minutes
• Fast realignment: 30 second

Question 6

Describe the meaning of the IRS DC FAIL light.

Answer 6

• Illuminated (amber) –

-DC backup power for the related IRS has failed.

Question 7

Describe the meaning of the IRS FAULT light.

Answer 7

• Illuminated (amber) – a system fault affecting the related IRS ATT and/or NAV modes has been detected.

Question 8

Know the function of the IRS selector and switch positions.

Answer 8

• IRS Mode selectors

Rotate – controls the mode of the related IRS.

• Must be pulled out to move from the NAV position.

OFF –
- Alignment is lost.
-The ALIGN light illuminates for 30 seconds as the
system goes through a shutdown sequence.
- Realignment requires about 10 minutes while the
airplane is parked. Re-entry of present position
(Latitude and Longitude) is required.

ALIGN –
- Initiates an alignment when the aircraft is parked.
- Initiates a fast realignment if selected when the
system
was in the navigation mode.

NAV –
- Normal operational mode.
- Permits the system to enter the NAV mode after
completing alignment.
- Initiates a 10 minute alignment if selected from OFF.

ATT –
- Provides only attitude and heading information.
- Position and ground speed information is lost until the
system is realigned on the ground.
- When selected airborne, the ALIGN light illuminates
for 30 seconds while the system senses local level which
requires level flight.
- A magnetic heading input is required to initialize
heading output.
- The selector must be cycled through OFF to re-enter
the ALIGN or NAV mode.

Question 9

Recall the IRS ALIGN lights should be allowed to
extinguish prior to either accomplishing a full alignment or selecting the battery switch to OFF.