PRIMUS
r
1000 Integrated Avionics System
A28--1146--112--00
8-39
Modes of Operation
D
Selecting the SG reversionary on the active side
D
Coupling to the cross--side FD.
D
The on--side AHRU or MADC become invalid.
WINDSHEAR (WDSHEAR) MODE
The windshear system uses a combination of detection and guidance.
The windshear detection computer annunciates an amber or red
WDSHEAR on the PFD for increasing performance or decreasing
performance windshears, respectively.
Any time an amber or red WDSHEAR is annunciated , as shown in
figure 8--25, the pilot is expected to apply full throttle, activate the
windshear mode, and execute a missed approach while following the
windshear guidance.
The windshear mode is activated manually by pushing the GA button
while an amber or red WDSHEAR annunciation is displayed. It is
activated automatically from the TO or GA modes if an amber or red
WDSHEAR occurs. It is also activated automatically from any mode if
a red WDSHEAR occurs and the throttles are greater than 80% of the
throttle lever angular travel.
When the windshear mode is active, the autopilot is disconnected and
the command bars are displayed. The command bars guide the aircraft
to gain energy or conserve energy depending on the conditions of the
airmass in which the aircraft is flying. This energy management is done
first by maintaining a slightly negative (climb) flight path angle. This
continues until the aircraft has either reached excess energy and
begins to control to a speed target for climb out or until the aircraft has
pitched up near stickshaker while trying to maintain the flightpath.
If the aircraft has reached excess energy, the aircraft switches from
flightpath control to speed control so the aircraft can reach whatever
climb rate it can while maintaining airspeed. Excess energy is defined
as the latched speed at time of windshear engagement, which is the
greater of 1.3Vs + 30 kts or current IAS. This speed latch is increased
by 20 knots if an increasing performance (amber) windshear is last
detected.
If the aircraft has pitched up while trying to maintain flightpath angle, the
windshear guidance controls to stickshaker until a climb can again
begin.
