Accident description
Last updated: 27 November 2014
Status:Final
Date:Friday 8 December 1972
Time:14:28
Type:Silhouette image of generic B732 model; specific model in this crash may look slightly different
Boeing 737-222
Operator:United Air Lines
Registration: N9031U
C/n / msn: 19069/75
First flight: 1968-09-24 (4 years 3 months)
Total airframe hrs:7247
Engines: 2 Pratt & Whitney JT8D-7B
Crew:Fatalities: 3 / Occupants: 6
Passengers:Fatalities: 40 / Occupants: 55
Total:Fatalities: 43 / Occupants: 61
Ground casualties:Fatalities: 2
Airplane damage: Damaged beyond repair
Location:2 km (1.3 mls) from Chicago-Midway, IL (   United States of America) show on map
Phase: Approach (APR)
Nature:Domestic Scheduled Passenger
Departure airport:Washington-National Airport, DC (DCA/KDCA), United States of America
Destination airport:Chicago-Midway Airport, IL (MDW/KMDW), United States of America
Flightnumber: 553
Narrative:
The aircraft, named "City of Lincoln", took off from Washington-National Airport for flight UA553 to Chicago and Omaha. Departure time was 12:50 CST. Chicago ARTCC cleared the crew to descend to 4000 feet and the flight was given vectors for a Midway Airport runway 31L localizer course. At 14:19 the flight was transferred to Chicago Approach Control which later requested UA553 to slow down to 180 knots and later down to 160 knots. After issuing a descent clearance down to 2000 feet at 14:23 the controller requested the flight to slow down to approach speed because of separation between UA553 and a preceding Aero Commander. At 14:24 the Aero Commander passed the Outer Marker and was cleared to land on runway 31L. Two minutes later UA553 passed the Outer Marker inbound. Then, at 14:27:04 the air traffic controller decided to issue a missed approach clearance: "United 553 execute a missed approach make a left turn to a heading of 180 climb to 2000". At the same time, having just reached 1000 feet, the stick shaker suddenly activated. Full power was applied and the gear was retracted in an attempt to execute a missed approach. The Boeing continued to descend however, attaining a high nose up attitude (of at least 30deg, according to some survivors). The aircraft then clipped a tree and impacted trees, houses, utility pole cables and garages before coming to rest. Post crash fire destroyed part of the fuselage.

PROBABLE CAUSE: "The captain's failure to exercise positive flight management during the execution of a non-precision approach, which culminated in a critical deterioration of airspeed into the stall regime where level flight could no longer be maintained."

Classification:
Loss of control

Sources:
» NTSB-AAR-73-16

Official accident investigation report
investigating agency: National Transport Safety Bureau (NTSB) - United States of America
report status: Final
report number: NTSB/AAR-73-16
report released:29-AUG-1973
duration of investigation:264 days (8.8 months)
download report: United Air Lines, Inc., B-737, N9031U, Chicago-Midway Airport, Chicago, Illinois, December 8, 1972. (NTSB/AAR-73-16)
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Follow-up / safety actions

NTSB issued 2 Safety Recommendations

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Map
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not display the exact flight path.
Distance from Washington-National Airport, DC to Chicago-Midway Airport, IL as the crow flies is 958 km (599 miles).

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