Copyright D.P. Browne 2011

Yaw Function

The Yaw function provides the following:

Yaw Damping

Rudder trim

Flight Envelope Function

Low Energy Warning

Wind sheer Detection

Flight Augmentation Computer (FAC)

The FMGS has two FACs that perform the following functions:

Yaw Function

Flight Envelope function

Low Energy Warning

Wind Sheer detection

The Flight Envelope function provides the following:

PFD speed scale Min/Max values

Alpha Floor protection

An aural warning of “SPEED” repeated every 5 seconds is given when  the FAC detects the aircraft’s energy level going below a threshold.

When wind sheer is detected, the FAC generates F/D guidance for the SRS mode. The flight crew should immediately set go-around thrust and follow the pitch F.D commands. The wind sheer warnings alert the flight crew to a wind sheer condition by:

Activating a WINSHEER text on the PFD for at least 15 seconds

An aural warning of “windsheer’ repeated 3 times.

When wind sheer detection is available from takeoff to 1300 ft and during approach below 1300 ft, with flaps in Config 1 or greater.

The FAC computes the low energy threshold as a factor of:

Aircraft configuration

Horizontal deceleration rate

Flight path angle

The low energy warning is inhibited when

TOGA mode is active

Below 100 ft or above 2000 ft radio altitude

Alpha Floor is triggered

Alternate or direct law active

Both radio altimeters fail

The FAC computes these attributes on the PFD speed scale

VMO/MMO, or VLE or VFE. Which ever is lowest

F

S

Minimum Slat Retraction Speed

Minimum Flap Retraction Speed

VFE Next , next flap lever setting speed

VLS

Alpha protect speed

Alpha Max speed