plural of pressure altitude

(medicine) A pathological condition caused by oxygen deficiency at high altitudes; symptoms include shortness of breath, nausea, and nosebleed.

(aviation) The lowest altitude at which an aircraft is permitted to fly during a non-precision approach without the runway being in clear sight.

plural of minimum descent altitude

(aviation) The lowest altitude which will provide a minimum clearance of 1000 ft (300 m) above all objects located in an area within a circular sector having a radius of 25 nautical miles (46 km) around a radio navigational aid.

plural of minimum sector altitude

(military, defence) A United States Army system designed to shoot down ballistic missiles in their terminal phase.