Can anyone please explain Decision Height ?

Question

I was reading my tr'ng manual and I saw in EFIS the ADI DH Ref was 150. Can any good pilots explain to me this decision height again please?

Much thanks, Sir.

Answer 1

Decision altitude (DA) is a specified altitude in an instrument approach procedure at which the pilot must decide whether to initiate an immediate missed approach if the pilot does not see the required visual reference, or to continue the approach. Decision altitude is expressed in feet above mean sea level.

Decision height (DH) is a specified height above the ground in an instrument approach procedure at which the pilot must decide whether to initiate an immediate missed approach if the pilot does not see the required visual reference, or to continue the approach. Decision height is expressed in feet above ground level.

Minimum descent altitude (MDA) is the lowest altitude specified in an instrument approach procedure, expressed in feet above mean sea level, to which descent is authorized on final approach or during circle-to-land maneuvering until the pilot sees the required visual references for the heliport or runway of intended landing.

(From the FAA FAR's Secton 1)

In lamens terms... The word DH and DA and MDA are used interchangably, but are slightly different. as DH  is height above the ground, AGL, and DA is in MSL. MDA is also shown in MSL, but used mainly on non precession approaches that dont offer glideslope information.

Answer 2

Sorry you have to keep reading long winded answers. At the DH, you either see the runway and land or you go around.