Navigation/FMC/FMS

Question 1

(757) If the left FMC fails, which autopilot may be used to enable LNAV and VNAV
operation?

Answer 1

Right

Question 2

What type of information is provided by the IRSs?

Answer 2

True and magnetic heading, acceleration, track, altitude
data, aircraft position, groundspeed, wind speed and
direction and vertical speed.

Question 3

Why does the ON DC light illuminate when the IRS Mode selector is positioned to
NAV?

Answer 3

IRS performs a short power test

Question 4

What is the difference between a normal and a fast alignment?

Answer 4

Some accumulated IRS errors can be removed by a 30‐

second realignment

Question 5

(767) If both AC busses are lost, what is the expected IRS configuration (HDG
operating) ?

Answer 5

Standby power to right IRS is limited to 5 minutes to save

battery power

Question 6

Where can you input present position required for normal IRS alignment?

Answer 6

CDU POS INIT page and IRS Mode Control Panel keyboard

Question 7

What does an L, C or R IRS ON DC EICAS message indicate?

Answer 7

Indicated IRS AC normal power has failed and the IRS DC

backup power is being used

Question 8

What does the IRS DC FAIL light indicate?

Answer 8

IRS DC backup power for the related IRS has failed

Question 9

What does the IRS FAULT light indicate?

Answer 9

A system fault affecting Related IRS ATT and/or NAV

modes detected

Question 10

What does an INSUFFICIENT FUEL CDU message indicate?

Answer 10

Predicted Fuel at destination is less than FMC reserves

Question 11

(757) If both AC busses are lost, what is the expected IRS configuration?

Answer 11

Standby power to left and center IRSs is limited to 5

minutes to save battery power