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Accident description
Last updated: 27 April 2017
Date:Thursday 21 March 1968
Type:Silhouette image of generic B721 model; specific model in this crash may look slightly different
Boeing 727-22C
Operator:United Air Lines
Registration: N7425U
C/n / msn: 19200/416
First flight: 1967-05-25 (10 months)
Total airframe hrs:2208
Engines: 3 Pratt & Whitney JT8D-1
Crew:Fatalities: 0 / Occupants: 3
Passengers:Fatalities: 0 / Occupants: 0
Total:Fatalities: 0 / Occupants: 3
Airplane damage: Damaged beyond repair
Location:Chicago-O'Hare International Airport, IL (ORD) (   United States of America)
Phase: Takeoff (TOF)
Departure airport:Chicago-O'Hare International Airport, IL (ORD/KORD), United States of America
Destination airport:San Francisco International Airport, CA (SFO/KSFO), United States of America
The takeoff warning horn sounded shortly after commencing takeoff from runway 09R. The takeoff was continued as the crew tried to figure out what caused the warning. The horn ceased prior to reaching rotate speed. The stickshaker came on and thrust was added, but the aircraft failed to climb and the captain elected to discontinue the takeoff. The 727 settled back to the macadam shoulder off the right side of the runway and struck a ditch, coming to rest 1100 feet beyond the runway end and 300 feet right of the extended centreline. The flaps had been set at 2deg instead of takeoff range of 5-25 degrees.

Probable Cause:

PROBABLE CAUSE: "The failure of the crew to abort the takeoff after being warned of an unsafe takeoff condition."


Official accident investigation report
investigating agency: National Transport Safety Bureau (NTSB) - United States of America
report status: Final
report number: NTSB/AAR-69-01
report released:31 December 1968
duration of investigation: 285 days (10 months)
download report: United Air Lines, Inc., Boeing 727 QC, N7425U, Chicago OHare International Airport, Illinois, March 21, 1968 (NTSB/AAR-69-01)

Follow-up / safety actions
Following a recommendation by the NTSB, the FAA reviewed the procedures prescribed in U.S. air carrier's manuals to ensure that takeoffs will be aborted whenever the takeoff warning horn sounds prior to reaching V1, unless there are other overriding factors.

NTSB issued 2 Safety Recommendations

Show all AD's and Safety Recommendations


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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 Chicago-O'Hare International Airport, IL to San Francisco International Airport, CA as the crow flies is 2943 km (1840 miles).

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Boeing 727

  • 8th loss
  • 8th fatal accident
  • 1832 built
  • 8th worst accident (at the time)
  • 61st worst accident (currently)
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