NORMAL CONDITIONS
When reaching 50 ft, the auto-trim ceases and the pitch law is modified to flare
law. Indeed, the normal pitch law, which provides trajectory stability is not the
best adapted for the flare manoeuvre. The system memorizes the attitude at 50
ft and that attitude becomes the initial reference for pitch attitude control. As the
aircraft descend through 30 ft, the system begins to reduce the pitch attitude at
a predetermined rate of 2° down in 8 seconds. Consequently, as the speed
reduces, the pilot will have to move the stick rearwards to maintain a constant
path. The flare technique is thus very conventional. Start the flare by
progressively increasing and holding the backpressure on the side stick. From
stabilized conditions, the flare height is about 30 ft. This height varies with
different parameters, such as weight, rate of descent, wind variations...
The roll is a roll rate law until the aircraft is on the ground.
At 20 ft, the "RETARD" auto call-out reminds the pilot to retard thrust levers. It is
a reminder rather than an order. The pilot will retard the thrust levers when best
adapted e.g. if high and fast on the final path the pilot will retard earlier.
In order to assess the rate of descent in the flare, and the aircraft position
relative to the ground, look well ahead of the aircraft. The typical pitch increment
in the flare is approximately 4°, which leads to -1° flight path angle associated
with a 10 kt speed decay in the manoeuvre. A prolonged float will increase both
the landing distance and the risk of tail strike.
CROSSWIND CONDITIONS
On initiation of the flare, rudder should be applied as required to align the aircraft
with the runway centreline. Any tendency to roll downwind should be counteracted
by an appropriate input on the sidestick. It is possible that a very slight wing
down may be required to maintain the aircraft on the runway centreline.
In the case of a very strong cross wind, a full de-crab in the flare may lead to a
significant bank correction which may reach the aircraft lateral geometry limit.
Consequently, combination of the partial de-crab and wing down techniques may
be required.