HAT and DA
Joined: Jun 2001
Posts: 518
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From: Chicago, IL, USA
More info in the Introduction of Jeppesen charts if you have them handy.
But in a nutshell:
HAT = Height Above Threshold
DA = Decision Altitude
DA is associated with precisions approaches (electronic glideslope).
DA is the altitude above mean sea level at which the pilot must have certain visual cues (e.g. lights) in sight in order to continue lower towards touchdown.
DH (= Decision Height) is the difference between DA (in MSL) and the elevation of the particular runway threshold.
MDA = Minimum Descent Altitude and is associated with non-precision approaches (no electronic glideslope).
HAT is the difference between MDA and the elevation of the particular runway threshold when landing "straight in" (more or less).
If circling then HAA = Height Above Airport and is the difference between MDA and airport elevation because you could conceivably circle to land any runway (unless stipulated as circling prohibited).
FYI = For Your Information.
Professional pilots continually confuse the terms DA, DH and MDA.
Your attention to detail will separate you from the rest.
But in a nutshell:
HAT = Height Above Threshold
DA = Decision Altitude
DA is associated with precisions approaches (electronic glideslope).
DA is the altitude above mean sea level at which the pilot must have certain visual cues (e.g. lights) in sight in order to continue lower towards touchdown.
DH (= Decision Height) is the difference between DA (in MSL) and the elevation of the particular runway threshold.
MDA = Minimum Descent Altitude and is associated with non-precision approaches (no electronic glideslope).
HAT is the difference between MDA and the elevation of the particular runway threshold when landing "straight in" (more or less).
If circling then HAA = Height Above Airport and is the difference between MDA and airport elevation because you could conceivably circle to land any runway (unless stipulated as circling prohibited).
FYI = For Your Information.
Professional pilots continually confuse the terms DA, DH and MDA.
Your attention to detail will separate you from the rest.
Joined: Jun 2003
Aviation Qualifications: ATPL
Posts: 263
Likes: 2
From: Canada
Professional pilots continually confuse the terms DA, DH and MDA
If that were true then "continually confuse the terms DA, DH and MDA" certainly negates this "Professional pilots"
Joined: Jan 2012
Posts: 510
Likes: 0
From: Not far from the edge of the Milky Way Galaxy in the Orion Arm.
DA DH MDA
Don`t forget the important bit - the most important bit, like:
what you may do at the MDA if nothing seen compared to what you must do at the DH if nothing seen - thought it worth a mention . . .
what you may do at the MDA if nothing seen compared to what you must do at the DH if nothing seen - thought it worth a mention . . .
Last edited by Natstrackalpha; 7th February 2012 at 14:56. Reason: can`t think of one right now
Joined: Jun 2001
Posts: 518
Likes: 0
From: Chicago, IL, USA
I just intended to provide a "nutshell" (as I said) summary.
I realize there are many, many little details we could pick at, but for someone who just asked about the different between HAT and DA, I think he has enough to chew on for the moment.
I realize there are many, many little details we could pick at, but for someone who just asked about the different between HAT and DA, I think he has enough to chew on for the moment.
