Can clouds affect the operation of a radio altimeter system?
When a radio altimeter reaches an altitude of 2500 feet or the radio altimeter stops receiving returned signals, the radio altimeter will set the output data to a No Computed Data configuration. In this configuration, the radio altimeter continues to transmit a signal with the receiver waiting to receive a returned signal. The purpose for continuous transmission is to insure the radio altimeter will capture and track any rising terrain. With the continuous transmission there are certain weather conditions that can result in returns of the transmitted signal. When a radio altimeter equipped aircraft is operating above 2500 ft ground level and less than 2500 ft above a very dense or precipitating cloud, a radio altimeter indication can occur. The occurrence may be momentary or may occur for several seconds.
