At 1331:58, UA Flight 757 reported that it was ready for takeoff on runway 35R. However, at 1332:05, 7 seconds later, it reported, "Ah, this is seven fifty seven, our sock sitting in front of us gives us a pretty good tail wind so we're not ready to go yet." The controller asked the flight to advise him when conditions were better.
1985 March 21, National Transportation Safety Board, “1.1 History of the Flight”, in Aircraft Accident Report: United Airlines Flight 663, Boeing 727-222, N7647U, Denver, Colorado, May 31, 1984, page 4