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Last updated: 27 April 2017
Datum:Mittwoch 31 März 1971
Flugzeugtyp:Silhouette image of generic B720 model; specific model in this crash may look slightly different
Boeing 720-047B
Fluggesellschaft:Western Air Lines
Kennzeichen: N3166
Werknummer: 19439/621
Baujahr: 1967-08-27 (3 years 7 months)
Anzahl Zyklen der Zelle:7011
Triebwerk: 4 Pratt & Whitney JT3D-3B
Besatzung:Todesopfer: 5 / Insassen: 5
Fluggäste:Todesopfer: 0 / Insassen: 0
Gesamt:Todesopfer: 5 / Insassen: 5
Sachschaden: Zerstört
Konsequenzen: Written off (damaged beyond repair)
Unfallort:Ontario International Airport, CA (ONT) (   USA)
Flugphase: Annäherung (APR)
Flug von:Los Angeles International Airport, CA (LAX/KLAX), USA
Flug nach:Ontario International Airport, CA (ONT/KONT), USA
Flugnummer: 366
Control was lost during a 3-engine missed ILS approach procedure and the aircraft crashed.
Failure of the aircraft rudder hydraulic actuator support fitting led to the loss of left rudder control. The loss of control situation was worsened by the degraded external visual clues (600 feet overcast; 1200 m visibility in fog haze and smoke).

Probable Cause:

PROBABLE CAUSE: "The failure of the aircraft rudder hydraulic actuator support fitting. The failure of the fitting resulted in the inapparent loss of left rudder control which, under the conditions of the flight, precluded the pilots’ ability to maintain directional control during a simulated engine-out missed-approach. The existing weather conditions degraded external visual cues, thereby hampering rapid assessment of aircraft performance by the flight check captain."


Official accident investigation report
investigating agency: National Transport Safety Bureau (NTSB) - United States of America
report status: Final
report number: NTSB/AAR-72-18
report released:7 June 1972
duration of investigation: 1 year and 2 months
download report: Western Air Lines, Inc., Boeing 720- 047B, N3166, Ontario International Airport, Ontario, California, March 31, 1971. (NTSB/AAR-72-18)


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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 Los Angeles International Airport, CA to Ontario International Airport, CA as the crow flies is 75 km (47 miles).

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Boeing 720

  • 6th loss
  • 5th Fataler Unfall
  • 154 built
  • 3rd worst accident (Zu diesem Zeitpunkt)
  • 4th worst accident (Momentan)
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