Ground Proximity Warning System callouts are standard audio cues in modern commercial aircraft, generated from the radio altimeter as the plane descends toward the runway. The number refers to height in feet, so thirty means the aircraft is thirty feet above the ground during the landing flare. Short recordings of these callouts circulate widely among flight simulation players and aviation enthusiasts, who reuse them to make virtual landings sound authentic. Their clipped, matter-of-fact delivery is why they remain instantly recognisable in cockpit videos and landing edits.