300 feet, Skipper.
3 seconds sound clip from the The High and the Mighty (1954) movie soundboard.
You can hear this line at 02:14:56 in the DVD version of the movie.
Quote context
[...]
- Twin Peaks coming up on your left in a minute or so.
- Remember those radio towers.
- Stay on course. Don't descend any more.
- Thanks. We're trying not to.
- 400.
- 4-2-0, this is San Francisco towers.
[...]