Auto Flight- General

Question 1

If AP1 is engaged, the related FMGC is master. It uses onside FD for guidance and controls:

Answer 1

-A/THR
-FMA 1 & 2

Question 2

If two APS are engaged, which is master?

Answer 2

FMGC 1

*also controls A/THR if no AP/FD is engaged.

Question 3

What mode will FMGS work in if each FMGC is loaded with a different database?

Answer 3

Independent mode

Question 4

What does pushing the V/S or FPA knob do?

Answer 4

Commands an immediate level off (by setting V/S or FPA to zero)

Question 5

VLS (Lowest Selectable Speed) is represented by the top of an amber strip along airspeed scale, and is computed on what values/configurations?

Answer 5

Takeoff/following a touch and go: 1.13VS

Retraction of one step of flap: 1.23VS

Clean config: 1.28VS

Above 20000ft VLS is corrected for mach effect to maintain a buffet margin of 0.2g.

Question 6

How is MIX IRS computed?

Answer 6

From an average of the 3 IRSs.

If one IRS drifts away, an algorithm is used to decrease its influence.

Question 7

What happens if an IRS fails?

Answer 7

Each FMGC uses only one IRS (onside or IRS 3)

Question 8

What is GPIRS and how is it computed?

Answer 8

Mix IRS/GPS position computed by each IRS.
FMS selects one based on a figure of merit and priority.

Question 9

What is BIAS and how is it used?

Answer 9

A vector from MIX IRS position to radio or GPIRS position.

If an FMGC loses its radio/GPIRS position, it calculates FM position as MIX IRS position plus BIAS.