decision altitude


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decision altitude (DA)

i. A specified altitude or height in the precision approach at which a missed approach must be initiated if the required visual reference to continue the approach has not been established. The decision altitude is with reference to mean sea level, whereas the decision height is with reference to the threshold elevation. The required visual reference means that section of the visual aids or of the approach area that should have been in view for a sufficient time for the pilot to be able to assess the aircraft's position and change of position in relation to the desired flight path. In Category III operations, with a decision height the required visual reference is that specified for the particular procedure and operation. For convenience, where both expressions are used they may be written in the form of “decision altitude/height” and abbreviated “DA/H.” These terms replace minimum height (MH), minimum descent (MD), minimum descent altitude/height [MDA (H)], and minimum descent height (MDH).
ii. The height at which a decision must be made, during an ILS (instrument landing system) or PAR (precision approach radar) instrument approach, either to continue the approach or to execute a missed approach.
References in periodicals archive ?
Asked by Senator Loren Legarda, chair of the committee, if the building would pose danger to the public, the CAAP official said: 'Now, it's not because we increased the minimum decision altitude.
Far more frequently, it's a matter of external stresses, fixation on a mission, a manifestation of confusion or simply the result of cumulative little errors that take us below decision height, decision altitude or the minimum descent altitude.
You merely count down the height above the decision altitude from which you'll begin the missed approach procedure.
You don't need to load any approaches in the GPS to do this, but if your GPS lets you load the approaches so you can get a magenta line to follow right to the missed approach point or decision altitude, so much the better.
Note 1: Decision altitude (DA) is referenced to mean sea level (MSL) and decision height (DH) is referenced to the threshold elevation.
You should be flying to a Decision Altitude (DA) and then landing or going missed.
Unlike precision approaches that take yon down to decision height (DH), a WAAS glidepath descends to DA, or decision altitude.
In my mind, this is the minimum descent altitude (MDA) for a non-precision approach, or decision altitude (DA) for an ILS or a GPS/VNAV procedure.
Altitude corrections should be made to all approach altitudes inside the final approach fix to include decision heights, decision altitudes and minimum decent altitudes (at -35 Celsius with a Height Above Terrain (HAT) of 200 feet, you will have to add 50 feet to your published decision height on the approach plate).
Using GE's method of merging RNP to the ILS, operators can experience the track mile reduction benefits of RNP with the lower decision altitudes a precision landing system provides," said Giovanni Spitale, general manager for GE Aviation's Air Traffic Optimization group.
Many decision altitudes (DAs), occur before the middle marker.