When reaching 100 ft, auto-trim ceases and the pitch law is modified to be a full authority direct law as described in OPERATIONAL PHILOSOPHY Chapter. Indeed, the normal pitch law, which
provides trajectory stability, would not be well adapted to the flare manoeuvre. Consequently, in the flare, 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.
Prior to flare, avoid destabilization of the approach and steepening the slope at low heights in attempts to target a shorter touchdown. If a normal touchdown point cannot be achieved or if destabilization occurs just prior to flare, a go-around (or rejected landing) should be performed. The PNF monitors the rate of descent and should call "SINK RATE" if the vertical speed is excessive prior to the flare.
From stabilized conditions, the flare height is about 40 ft.
This height varies due to the range of typical operational conditions that can directly influence the rate of descent.
Compared to typical sea level flare heights for flat and adequate runway lengths, pilot need to be aware of factors that will require an earlier flare, in particular:
? High airport elevation.
Increased altitude will result in higher ground speeds during approach with associated increase in descent rates to maintain the approach slope.
? Steeper approach slope (compared to nominal 3 °).
? Tailwind.
Increased tailwind will result in higher ground speed during approach with associated increase in descent rates to maintain the approach slope.
? Increasing runway slope.
Increasing runway slope and/or rising terrain in front of the runway will affect the radio altitude callouts down to over flying the threshold used by the flight crew to assess the height for the start of flare possibly causing flare inputs to be late. The visual misperception of being high is also likely.
Note that the cumulative effect of any of the above factors combined for one approach will require even more anticipation to perform an earlier flare.
If the flare is initiated too late (below 25 ft) then the pitch changes will not have sufficient time to allow the necessary change to aircraft trajectory. Late, weak or released flare inputs increase the risk of a hard landing.
NORMAL OPERATIONS
LANDING
Avoid under flaring.
? The rate of descent must be controlled prior to the initiation of the flare (i.e. nominal 3 ° slope and rate not increasing)
? Start the flare with positive (or "prompt") backpressure on the sidestick and holding as necessary
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