UAM.IDE.MVCA.145 Height-determination equipment

RADIO ALTIMETER A radio altimeter capable of emitting an audio warning below a preset height and a visual warning at a height selectable by the PIC may be used to meet the safety objective of point UAM.IDE.MVCA.145.

AUDIO AND VISUAL WARNING

(a)The audio warning should be a voice warning. The voice warning alert should be distinguishable from other warnings and should contain a clear and concise voice message. The height at which the audio warning is triggered should be such as to provide adequate time for the PIC to take corrective action. The voice warning should be triggered only whilst descending through the preset datum height and be inhibited whilst ascending.

(b)The visual warning should require minimal interpretation by the PIC for both an instantaneous impression of absolute height and the rate of change of height.

TAWS A VCA equipped with a TAWS is considered to meet the requirements of point UAM.IDE.MVCA.145.

It is recommended that an audio warning be triggered at a height in the range of 100–160 ft. The datum should not be adjustable in flight. Once triggered, the audio warning message should sound within 0.5 seconds.