In larger aircraft, the warning system usually excludes the engine power setting and instead warns the pilot when the flaps are set for landing but the landing gear is not. An alternative system uses the ground proximity warning system or radar altimeter to engage a warning when the airplane is close to the ground and descending with the gear not down. Most airliners incorporate a voice message system which eliminates the ambiguity of a horn or buzzer and instead gives the pilot a clear verbal indication: "GEAR NOT DOWN".