60 Years ago today: On 17 March 1960 a Northwest Orient Lockheed L-188 Electra crashed near Cannelton, IN following an in-flight wing separation, killing all 63 occupants.

Date: Thursday 17 March 1960
Time: 15:25
Type:
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: 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. “