1965 — Aug 16, United 389 Approach Crash (cause unclear), Lake Michigan, off IL — 30

–30 Kimura. World Commercial Aircraft Accidents 3rd Ed., 1946-1993, V.1. 4-11-1994, p. 2-50.
–30 NTSB AAR. United Air Lines…B-727, N7036U, In Lake Michigan, Aug 16, 1965. 1967
–30 Wikipedia. “United Airlines Flight 389.”

Narrative Information

NTSB: “A United Air Lines, Inc., B-727-22, N7036U, Flight 389 crashed into Lake Michigan approximately 19.5 statute miles east of Lake Forest, Illinois, at approximately 2120 c.d.t., August 16, 1965. The 24 passengers and 6 crewmembers died in the crash and the aircraft was destroyed.

“Flight 389, en route from LaGuardia Airport, New York to O’Hare International Airport, Chicago, Illinois, was descending from a cruising altitude of 35,000 feet to begin a landing approach when its radar target disappeared from the air traffic controller’s radarscope. The weather at O’Hare at the time of the accident was: an estimated ceiling of 10,000 feet, visibility 7 miles. Ground witnesses observed a fire and explosion on the lake at approximately 2121. Search vessels discovered the first floating wreckage approximately five hours later.

“At 2103 the ARTCC controller cleared UAL 389 to descend to FL 240 and to “start descent now through 31” (FL 310). UAL 389 replied “…down to 240, leaving three five.” At 2106 UAL 389 was cleared to continue its descend to 14,000 feet and given an altimeter setting of 29.90 inches for O’Hare. This message was acknowledged immediately and in reply to the controller’s inquiry the crew reported they were leaving FL 280 “now.” At 2109 the flight was instructed to change frequencies and within the same minute reported out of FL 260 descending to fourteen thousand….At 2111 the flight was cleared to descend to 6,000 feet and the clearance was immediately acknowledged correctly. At 2118:35 control of the flight was passed to Chicago Approach Control (ORD). The radar target of UAL 389 was in the vicinity of the Sturgeon Intersection…28 miles east of Northbrook VORTAC). At 2118:38 the target was observed approximately 2 miles east of the intersection. At 2119:36 the crew contacted ORD and was advised that radar contact had been established. At this time the aircraft target was 2-3 miles west of Sturgeon. UAL 389 was cleared to maintain 6,000 feet and to depart the Northbrook VORTAC on a heading of 240 degrees. The flight was advised that instrument landing system approaches were in progress on runway 14R at O’Hare and that the current O’Hare altimeter setting was 29.93. The pilot 3 read back the altimeter setting incorrectly, the controller corrected him, and the pilot repeated it correctly. This was the last communication received from the flight and ended at 2120:03….

“Several witnesses on ships and along the western shore of Lake Michigan observed a ball of fire near the surface of the lake. These witnesses placed the time of their observation at 2120. Other witnesses reported the same general sightings but the time of their observations varied from 2100 to after 2130.

“The accident location was determined by plotting the center of the wreckage distribution pattern and determined to be at a point 29.6 statute miles east-northeast of O’Hare Airport in 250 feet of water…. The main wreckage area was located on September 2, 1965, and the center plotted as 87 degrees 27’56” West-42 degrees 15’02” North. Several thousand pounds of floating material were recovered from the lake in the three days following the accident but little else until the discovery of the main wreckage area. Recovery operations were discontinued December 21, 1965, with approximately 82 percent of the wreckage by weight, and all occupants of the aircraft recovered.

“Search and recovery operations were resumed June 17, 1966, and terminated September 25, 1966. Particular emphasis was given to the recovery of the flight recorder, the flight recorder tape, and the missing portions of the No. 3 engine. No flight recorder parts or tape were recovered during this search. One small piece of an engine case was recovered with a small section of flange mounting and case splice attached. Approximately 1,500 pounds of additional wreckage was recovered, consisting mostly of wing skin and small fuselage parts….

“A majority of the witnesses reported an explosion and fire on or just above the horizon over Lake Michigan. Those witnesses nearest the accident, on ships in the area, reported the time of the explosion at about 2120. Several pieces of floating wreckage were recovered which exhibited smoke and soot discoloration particularly on the broken edges. While there was a fire and explosion on impact with the water, there is no evidence of a fire in flight.

“This was a non-survivable accident. Pathological and toxicological examinations of the flight crew revealed no evidence of pre-impact incapacitation nor was there any evidence of foul play….

“A review of the available evidence has eliminated all causal areas other than those involving the operation of the aircraft. No evidence was found that would indicate other than normal operation of the powerplants and systems at the time of impact. There is no evidence that will support a finding of sabotage, flight crew incapacitation, or any malfunction of the aircraft. There is no indication that the weather played any part in this accident…. There is no evidence on which we can base a finding of engine failure before impact…. The recovered air conditioning ducting revealed no evidence of fire or smoke….

“The crew of this flight indicated no concern in their last radio contact with the approach controller and were within 15 seconds of impact at the time of the last transmission. The crew had already descended below their assigned altitude of 6,000 feet and the accident was about to occur. Lastly, the evidence indicates the aircraft initially struck the water in a normal descent attitude.

“Examination of the recovered components of the hydraulic system reveal no evidence of pre-impact malfunction….

“The investigation of medical records, pathological findings, and toxicological results revealed nothing indicative of pre-existing disease or inflight incapacitation of any flight crewmember. Further, a study of associated psychophysiological factors such as recent schedules, recent psychological environment, and miscellaneous background data led to the conclusion that no physical or emotional impairment existed in the cases of any of the flight crewmembers when the aircraft departed New York.

“The evidence indicates that the flight from New York to the point where the descent was initiated was normal and routine without any reported discrepancies or difficulties. A review of the air traffic control transcriptions reveals no evidence of any irregularities or signs of unusual operation on the part of the crew. The record also indicates that there was no known or observed traffic that conflicted with UAL 389 during the period of its observation on radar inbound from the Pullman VORTAC. Additionally there were no components of another aircraft in the recovered wreckage nor were any aircraft reported missing in the accident area….

“There was no evidence in the recovered engine cowling and surrounding structure to indicate that anything had been ejected through the engine cowlings prior to impact.
Probable Cause

“The Board is unable to determine the reason for the aircraft not being leveled off at its assigned altitude of 6,000 feet.” (NTSB. AAR. United Air…In Lake Michigan, August 16, 1965. 1967)

Wikipedia: “A definitive cause was not determined by NTSB investigators. However, it was believed that the crash was most likely the result of the pilots misreading their three-pointer (3p) altimeters by 10,000 feet…. The most likely explanation is the pilots thought they were descending through 16,000 feet MSL when they were actually descending through 6,000 feet MSL. Time and radar image analysis indicated the plane was already down to an altitude of between 1,000 to 2,500 feet MSL when it was given the 6,000 foot clearance limit. That final clearance was acknowledged by the Captain, and was the last communication with ATC, prior to impact with the water…. A study by the Naval Research Laboratory, published in January, 1965, found that, of four different designs of pilot altimeters, the 3p design was the one most prone to misreading by pilots. In fact, that extensive study revealed that the 3p design was misread almost 8 times more often than the best designed of the four altimeters tested. It was also noted that it took the pilots considerably longer to decipher the correct reading of the 3p than was the case with the other altimeters.” (Wikipedia. “United Airlines Flight 389.”)

Sources

Kimura, Chris Y. World Commercial Aircraft Accidents 3rd Edition, 1946-1993, Volume 1: Jet and Turboprop Aircrafts. Livermore, CA: Lawrence Livermore National Laboratory, Risk Assessment and Nuclear Engineering Group. 4-11-1994.

National Transportation Safety Board. Aircraft Accident Report. United Air Lines, Inc. B-727, N7036U In Lake Michigan August 16, 1965 (NTSB/AAR 67-AA; NTIS PB196965). Washington, DC: NTIS, Aug 16, 19654, 45 pages. Accessed at:
http://libraryonline.erau.edu/online-full-text/ntsb/aircraft-accident-reports/AAR67-AA.pdf

Wikipedia. “United Airlines Flight 389.” http://en.wikipedia.org/wiki/United_Airlines_Flight_389