Abstract: A ground proximity warning system and a detector for aircraft having fixed or non-retractable landing gear which rather accurately detects a landing phase of flight in order to adjust the warning envelope to minimize nuisance warnings during such a phase of flight. In particular, the system monitors the flap position to provide an indication to the ground proximity warning system that the aircraft is either in an approach, cruise or landing phase of flight. Cams mounted to the air flaps system indicate a landing phase of flight when the approach flaps are configured for a normal landing, such as 16.degree.-18.degree. flaps or an approach phase of flight when the flaps are configured for a normal approach, for example, 5.degree.-7.degree. flaps. By providing a relatively accurate indication of the phase of flight for an aircraft with non-retractable landing gear, nuisance alarms will be virtually eliminated, while maximum protection is provided during all phases of flight.