FMS Navigation

Question 1

If ADIRU fails inflight what EICAS should you see?

What is happening?

Answer 1

EICAS displays the message NAV ADIRU INERTIAL

FMC uses only GPS data to navigate.

Question 2

What does the ADIRU provide?

Answer 2

ADIRU supplies primary flight data, inertial reference, and air data.

Question 3

What is the Secondary Attitude and Air Data Reference Unit (SAARU) and what does it do?

Answer 3

SAARU is a secondary source of critical flight data for displays, flight control systems, and other systems.

If the ADIRU fails, the SAARU automatically supplies attitude, heading, and air data. SAARU heading must be manually set to the standby compass magnetic heading periodically.

Question 4

When will LNAV engage after takeoff?

Answer 4

When armed on takeoff, LNAV engages at or above 50 feet, when laterally within 2.5 nautical miles of the active route leg.

Question 5

When does the airplane transition to approach mode?

Answer 5

• The airplane is in descent mode and the flaps are out of up, or
• The airplane has sequenced the first waypoint of the active approach, or
• The airplane is on a direct-to or intercept-to the active waypoint and the distance to go is less than 12 no
• The missed approach point is the active waypoint and the distance to go is less than 25 nm

Transitions out or “on approach” when TO/GA is selected, the airplane lands, or flys beyond the last waypoint on the approach