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
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-
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