United Air Lines Flight 389Monday August 16, 1965
The plane crashed into Lake Michigan 19.5 miles east of Lake Forest, Illinois during an approach and while descending from FL 350. The aircraft made a continuous descent at an average rate of approximately 2,000 feet per minute from 35,000 feet to impact with the water in a clean flight configuration. Officially, a cause could not be determined. The aircraft was dispatched illegally without an operating CVR. Possible misread altimeter. The crew could have read the altimeter as 16,000 instead of 6,000 ft. and continued a descent below what they were cleared for. Possible excessive sink rate. Excessive sink rate is thought to have possibly caused four 727 accidents in succession. Lake Michigan 8/16/65, Cincinnati 11/8/65, Salt Lake City 11/11/65 and Tokyo Bay 2/4/66. Only the Salt Lake and Cincinnati crashes were officially attributed to it. After 727 training manuals were modified and pilots were reoriented to the flying characteristics of the aircraft the problem was corrected.