The Atlantis Avionics ARA-552 Radio Altimeter Analog Adapter is designed to facilitate flight line testing of aircraft autoland systems, ground proximity warning systems, and installed altimeter systems. Together with the ARA-552 Hand Held Controller, it provides sophisticated capabilities for testing a wide range of analogue altimeters in a variety of aircraft. The ARA-552 Test Set facilitates testing of analogue altimeters by providing simulated aircraft radio altitude information in a flight-line environment. Using operator-defined parameters such as start altitude, stop altitude, and vertical speed, the Test Set defines a radio altitude ramp. This information, along with error and fault control information, is transmitted through a cable adapter to up to three aircraft altimeters. The three-part sequence accurately simulates descent, approach, flare, and touchdown. The ARA-552 Test Set may be used whenever active control of the radio altitude bus is a test requirement.