The 980N-1 Altimeter Test Set is used primarily to isolate faults in the AL101 or AL-101A Radio Altimeter System and to perform routine flight-line maintenance tests on the system, while it is installed in the aircraft. It also has limited capabilities for operationally bench-testing the 860F-1 Radio Altimeter and 339H-1( ) Radio Altitude Indicator. The 980N-1 Altimeter Test Set in addition to the above, provides a varying altitude rate signal to the radio altimeter system necessary to test the Ground Proximity Warning System (GPWS), and provides automatic descent rates for autoland tests.

980N-1