This cautionary sign is posted near a small local airport (in Ashland, Oregon).
But as the town's altitude is a little over 2000 feet (or 700 meters) above sea-level - and since my GTV, 'Pazzo', was formerly owned by a Navy pilot - I think perhaps she qualifies. (Note: in the present photograph, Pazzo had just come in for a landing - but was about to take off again!)