Instrument approach

Under Decision Height is understood in the aviation, the height above the threshold of each runway, when the cockpit crew of an approaching aircraft shall decide by whether the landing continued and finished with a landing or whether the approach is aborted and restarted. The decision height for an approach is published for the approach and the approaching aircraft category minimum height at which there is still freedom of obstacles ( obstacle clearance height, and OCH, or obstacle clearance altitude, and OCA ), and a determined by the aircraft operator security surcharge determined.

For precision approaches, eg by instrument landing system (ILS ), a distinction between two types of decision heights:

• Decision height ( DH) is the height above the runway and is usually measured by a radar altimeter. It is used in the ILS category ( CAT), II and III.
• Decision altitude (DA) is the height above sea level and is measured by a barometric altimeter. It is only used in CAT I

For non- precision approaches but there is no decision heights as a precision approach, but only Mindestsinkflughöhen. The aircraft can drop to this level and continue to fly at this altitude until the missed approach point, even MAPt ( missed approach point) accordingly until you can see the approach lights or the runway. This Sinkhöhen are designated as follows:

• Minimum descent height ( MDH)
• Minimum descent altitude (MDA )