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Last updated: 12 July 2020
Status:Final
Date:Thursday 17 March 1960
Time:15:25
Type:Silhouette image of generic L188 model; specific model in this crash may look slightly different
Lockheed L-188C Electra
Operator:Northwest Orient Airlines
Registration: N121US
C/n / msn: 1057
First flight: 1959-07-01 (9 months)
Total airframe hrs:1786
Engines: 4 Allison 501-D13
Crew:Fatalities: 6 / Occupants: 6
Passengers:Fatalities: 57 / Occupants: 57
Total:Fatalities: 63 / Occupants: 63
Aircraft damage: Destroyed
Aircraft fate: Written off (damaged beyond repair)
Location:9 km (5.6 mls) NE of Cannelton, IN (   United States of America)
Phase: En route (ENR)
Nature:Domestic Scheduled Passenger
Departure airport:Chicago-Midway Airport, IL (MDW/KMDW), United States of America
Destination airport:Miami International Airport, FL (MIA/KMIA), United States of America
Flightnumber: 710
Narrative:
Northwest Orient Airlines Flight 710, was a scheduled service from Minneapolis (MSP) to Chicago (MDW) and Miami (MIA).
The Lockheed L-188C Electra departed Minneapolis at 12:51 and arrived at Chicago-Midway Airport at 13:55. During the short time the aircraft was on the ground at Chicago, approximately 30 minutes, it was refueled and prepared for continuation of the flight to Miami. The flight took off from Midway Airport at 14:38.
At 15:13, Flight 710 reported over Scotland, Indiana, maintaining 18000 feet and estimating Bowling Green, Kentucky, at 15:35. This was the last radio contact with the flight.
At 15:25 the outboard engines and engine support structures, the complete right wing, and the outer portions of the left wing and ailerons separated in flight. The aircraft crashed out of control.

Probable Cause:

PROBABLE CAUSE: "The Board determines that the probable cause of this accident was the separation of the right wing in flight due to flutter induced by oscillations of the outboard nacelles. Contributing factors were a reduced stiffness of the structure and the entry of the aircraft into an area of severe clear air turbulence. "

Accident investigation:
cover
Investigating agency: CAB
Status: Investigation completed
Duration: 1 year and 1 months
Accident number: Final report
Download report: Final report

Classification:
Turbulence
Wing failure
Loss of control

Follow-up / safety actions
The FAA requested Lockheed to conduct an engineering reevaluation of Electra model airplanes following two fatal accidents (Sept. 1959 and March 1960).
The program disclosed two discrepancies in the design of the airplane. One, significant loads imposed on the wing's intermediate ribs between the fuselage and outboard nacelles by shell distortion had not been included in the design loads. Two, the dynamic response of the outboard nacelles in turbulence was different from the design assumptions.
Lockheed redesigned the engine mounts, nacelles, and cowlings, and modified the wing to improve strength capabilities. No Electra accidents have resulted from whirl-mode flutter since.

FAA issued 2 Emergency Airworthiness Directives

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Photos

photo of Lockheed-L-188C-Electra-N121US
accident date: 17-03-1960
type: Lockheed L-188C Electra
registration: N121US
photo of Lockheed-L-188C-Electra-N121US
accident date: 17-03-1960
type: Lockheed L-188C Electra
registration: N121US
photo of Lockheed-L-188C-Electra-N121US
accident date: 17-03-1960
type: Lockheed L-188C Electra
registration: N121US
photo of Lockheed-L-188C-Electra-N121US
accident date: 17-03-1960
type: Lockheed L-188C Electra
registration: N121US
 

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 Chicago-Midway Airport, IL to Miami International Airport, FL as the crow flies is 1892 km (1183 miles).
Accident location: Exact; as reported in the official accident report.

This information is not presented as the Flight Safety Foundation or the Aviation Safety Network’s opinion as to the cause of the accident. It is preliminary and is based on the facts as they are known at this time.
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Lockheed L-188

  • 222 built
  • 3rd loss
  • 3rd fatal accident
  • 2nd worst accident (at the time)
  • 8th worst accident (currently)
» safety profile

 United States of America
  • 6th worst accident (at the time)
  • 46th worst accident (currently)
» safety profile