ED
Decision 2022/012/R
DECISION
ALTITUDE (DA) OR DECISION HEIGHT (DH)
(a) Decision altitude (DA) is referenced to
mean sea level and decision height (DH) is referenced to the threshold
elevation.
(b) For operations using DA, the aircraft
altimeters are set to QNH. For operations using a barometric DH, the aircraft
altimeters are set to QFE.
(c) For SA CAT I, SA CAT II, CAT II/III
operations, the DH is based on the use of a radio altimeter or other devices
capable of providing equivalent performance. The DH is determined with
reference to threshold elevation, but the value of the DH set for the approach
will be based on the height of the aircraft above the pre-threshold terrain,
which may be higher or lower than the threshold.
(d) For convenience, when both expressions are
used, they may be written in the form ‘decision altitude/height’ and
abbreviated ‘DA/H’.
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