December 8, 1972
Chicago, Illinois
United Air Lines, Flight 553
Boeing B-737-222
N9031U


The aircraft crashed while making a non-precision instrument approach to Runway 31L. The
accident occurred in a residential area approximately 1.5 miles southeast of the approach end
of Runway 31L. Upon reaching minimum descent altitude, the pilot raised the nose of the
aircraft to stop the descent. The stall warning horn sounded and continued to sound until the
plane crashed 17 seconds later. The aircraft was destroyed by impact and subsequent fire.
Forty-three of 61 aboard killed.

RDO - Radio transmission from accident aircraft
CAM 1 - Voice identified as Captain
CAM 2 - Voice identified as First Officer
CAM 3 - Voice identified as Second officer
? - Unidentifiable voice
CHI APC = Chicago Approach
MTWR = Chicago-Midway Tower
* - Unintelligible word
# - Expletive deleted
() - Questionable text
9VS = Aero Commander 690, N309VS pilot

20.25:25.0 CHI APC Five five three, call the tower on one eighteen seven
20.25:28.0 RDO-2 Eighteen seven, five five three
20.25:35.5 RDO-2 Midway tower, United five five three, an' we're out of three for two
20.25:39.0 MTWR United five five three, report passing the outer marker, number two on the approach
20.25:41.0 CAM-3 Chicago, this is five five three (2nd officer calling ARINC)
20.25:44.0 RDO-2 Okay, report the outer marker
20.25:46.5 CAM-1 Let's have the gear down please
20.25:48.0 RDO-1 [Start of first sound of first series off outer marker beacon tones]
20.25:50.97 CAM-3 Chicago, five five three (2nd officer calling ARINC)
20.25:51.62 CAM [Sound of a click - sound similar to sound of landing gear handle going into down detent]
  CAM [Sound of chime - simultaneous with click above]
20.25:52.20 MTWR Nine Victor Sugar, what's your airspeed?
20.25:54.5   [End sound of first series of outer marker beacon tones]
20.25:54.74 9VS Ah, we're down to ah, hundred twenty knots
20.25:55.06 CAM [Increase in ambient noise level - similar to increase made by nose landing gear extended]
20.25:56.82 MTWR Ah hundred and twenty, okay
20.26:00.64 CAM [Sound of first of four clicks in rapid increase - sounds similar to flap lever moved from 15 degrees to 25 degrees position]
20.26:01.50 CAM-? Gear 'own
  CAM [Sound of several clicks - similar to sound of stabilizer trim actuation]
20.26:10.02 RDO-1 [Sound of beginning of second series of outer marker beacon tones]
20.26:20.02 RDO-1 [End of sound of second series of outer marker beacon tones]
20.26:24.66 CAM-1 Final descent check
20.26:25.66 CAM-3 Flight and nav
20.26:27.11 CAM-2 Cross-checked
  CAM-? * *
  CAM [Sound of clicks - similar to sound of stabilizer trim actuation]
20.26:30.62 RDO-2 United five five three, an, ah Kedzie inbound
20.26:35.97 CAM-? Flight
20.26:36.38 MTWR United five five three, continue inbound, you're number two on the approach --I'll keep you advised.
20.26:40.10 CAM [Sound of several clicks - similar to sound of electrical stabilizer trim actuation]
20.26:40.47 RDO-2 Okay
20.26:40.96 CAM-2 Cross-checked
  CAM-3 With a glideslope flag
  CAM-2 No glideslope
20.26:41.10 9VS Eh, nine VS has the runway
20.26:43.06 MTWR Nine VS, runway three one left cleared to land
20.26:44.67 CAM-3 Ah the --- landing gear
20.26:46.18 9VS Okay
20.26:48.40 MTWR Nine VS, do ya have the right runway in sight by any chance?
20.26:50.41 CAM-2 Down, three greens
20.26:51.37 CAM-3 Speed brake?
20.26:51.37 9VS Affirmative
20.26:52.45 CAM-2 Ah --- armed
20.26:52.6 MTWR would you swing over to that and land? There's a jet about two m-- and disregard that, ah, okay, I see ya now, you're cleared to land on thirty-one left
20.26:54.69 CAM [Sound of click - similar to sound made by moving speed brake lever to armed position]
20.26:56.04 CAM-3 Wing flaps
20.26:58.75 CAM [Sound of click - similar to sound made by flap lever moving into detent]
20.26:59.42 CAM-2 Thirty, green light, pressure fluid.
20.27:01.48 CAM-3 An the auto-pilot?
  CAM [Sound of click - similar to electrical stabilizer trim actuation]
20.27:02.96 CAM-2 Disarmed
20.27:04.11 CAM-2 Ah thousand feet
20.27:04.50 MTWR United five fifty-three, execute a missed approach, make a left turn to a heading of --- one eight zero, climb to two thousand [between words 'of' and 'one' there is a pause and a voice in the background says 'one eighty']
20.27:05.74 CAM [Sound of stickshaker begins and continues to end of recording]
20.27:07.56 CAM-? [Two to three hurried word at very low amplitude and masked by noise of stickshaker]
  CAM [Sound of click - similar to sound made by flap lever moving into detent]
20.27:12.14 RDO-2 Okay, left turn to one eight zero, --- left turn okay?
20.27:13.88 CAM-3 Want more flaps?
20.27:15.33 CAM-? Flaps fifteen.
20.27:15.45 MTWR Yeah, make left turn to one eighty.
20.27:16.14 CAM-? I'm sorry.
20.27:16.47 CAM [Sound of click - similar to sound made by flap lever moving into detent]
20.27:19.4 CAM [Sound of click - similar to sound made by landing gear lever moved out of detent]
20.27:20.14 CAM [Sound of double click - similar to sound made by landing gear lever moved into up detent]
20.27:10.64 CAM [Sound of landing gear warning horn begins and continues to end of recording]
20.27:23.55 CAM [Sound of initial impact and garbled voice]
20.27:24.46 RDO-1 [Sounds of impact and unintelligible voice]
20.27:25.02 RDO-1 end of recording.

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