Northwest Airlines Flight 710
| Northwest Airlines Flight 710 | |
|---|---|
.jpg) An identical Lockheed L-188 Electra of Northwest Airlines |
|
| Accident summary | |
| Accident type | Structural failure |
| place |
Tobin Township , Perry County , near Cannelton , Indiana , United States
|
| date | March 17, 1960 |
| Fatalities | 63 |
| Survivors | 0 |
| Aircraft | |
| Aircraft type |
 Lockheed L-188 Electra
|
| operator |
Northwest Airlines
|
| Mark |
N121US
|
| Departure airport |
Minneapolis-Saint Paul International Airport , Minnesota , United States
|
| Stopover |
Chicago Midway Airport , Chicago , Illinois United States
|
| Destination airport |
Miami International Airport , Miami , Florida United States
|
| Passengers | 57 |
| crew | 6th |
| Lists of aviation accidents | |
On the Northwest Airlines Flight 710 , a crashed on March 17, 1960 Lockheed L-188 Electra of Northwest Airlines after the machine was broken apart in the air. All 63 occupants of the machine were killed in the accident. In the course of the accident investigation, the cause of the crash on Braniff International Airways flight 542 could also be clarified a few months earlier.
plane
The crashed machine was a Lockheed L-188 Electra with the serial number 1057, which completed its maiden flight on July 1, 1959 and was first delivered to Northwest Airlines on July 19, 1959 with the aircraft registration N121US . The four-engine narrow-body aircraft was equipped with four turboprop engines of the type Allison 501-D13 equipped. The cumulative operating performance of the machine at the time of the accident was 1786 operating hours.
Flight history
Flight 710 took off from Minneapolis-Saint Paul International Airport at 12:51 p.m. local time . The first leg of the flight up to the stopover at Chicago Midway Airport at 1:55 p.m. went without a special incident, except for a hard landing of the plane, which some passengers complained about.
After the stopover, the aircraft was refueled and prepared for the onward flight. 57 passengers and 6 crew members took the onward flight. At 2:38 p.m. the machine took off again. Before departure, the pilots had been briefed by a meteorologist from the airline regarding existing and expected weather conditions along the route. No warning of Clear Air Turbulence , a weather phenomenon that could lead to structural overload, was issued. At 14:55 local time, the crew reported to air traffic control in Indianapolis on the last leg of the flight to Miami International Airport and stated their altitude as 18,000 feet (approx. 5500 meters). At 3:13 p.m., the crew reported again to air traffic control, stated that they were over Scotland , Indiana and that they would maintain the flown altitude of 18,000 feet.
the accident
As witnesses later reported, the machine is said to have broken apart in the air around 3:25 p.m. The right wing was torn off in one piece and the rest of the machine then crashed near Cannelton in the south of the state of Indiana . During the events, six United States Air Force (USAF) aircraft were in the vicinity as part of an aircraft refueling maneuver, and they were flying at an altitude of 31,000 to 32,000 feet (9450 to 9750 meters). The crew members of the machines stated in interviews that they first saw a column of smoke in the air at 3:32 p.m. Witnesses on the ground said they saw two puffs of white smoke followed by a large cloud of black smoke. They heard two loud explosions, whereupon a large object emerged from the cloud of smoke and fell almost vertically to the ground, leaving a trail of smoke and flames behind it. The hull hit the ground, hurling wreckage nearly 250 feet (75 meters) into the air.
Accident investigation
The investigation was conducted by the Civil Aeronautics Board (CAB). The investigators initially investigated three possible theses - an explosion caused by a bomb on board, a structural failure due to turbulence and a structural failure due to material fatigue.
Due to the amount of debris lying around and its scattering range, the rumor initially circulated that two machines had collided in the air, but the Federal Aviation Administration and the police announced a little later that all the wreckage found from an aircraft, the Lockheed L- 188 Electra belonged to Northwest Airlines with registration number N121US . A wing and two engines were found about five miles from where the machine's fuselage hit. At this point the machine had pitched from a vertical attitude and at high speed. This created a crater in the ground that was 25 feet (about 7.6 meters) deep and 40 feet (about 12 meters) wide. Hours after the crash, a blue-gray column of smoke rose from the crater.
NASA , Boeing and Lockheed investigators finally came to the conclusion that the crash was caused by a right wing torn off in flight. At this point in time, the machine was at an altitude of 18,000 feet (approx. 5500 meters). The material failure occurred as a result of a flutter caused by a material weakness in the area of an engine pylon. The investigators referred to the phenomenon as vortex mode. Half a year earlier, an identical aircraft on Braniff International Airways Flight 542 crashed for the same reason. What caused the material weakness could not initially be determined.
The commission of inquiry later turned its attention to the hard stopover in Chicago described by passengers. The investigators suspected that this hard landing could have led to an unnoticed weakening of the engine pylon, which resulted in the flutter. In order to prove their thesis, the investigators had a model of an Electra made on a 1: 8 scale and tested it in a NASA wind tunnel. During the attempt, the right wing including the two engines broke off, as calculated by the investigators.
Final report
The final report was published on April 24, 1961. The CAB investigators concluded that the engine pylon of engine number 4 was damaged during the hard stopover in Chicago. The initially undiscovered structural damage to the engine pylon led to the vibrations of the engine nacelle being transferred to the wing structure, which it could not withstand. So it finally came to the demolition of the wing including the engines.
swell
- Accident report of the Civil Aeronautics Board , April 24 1961st
- Aircraft accident report in the Aviation Safety Network
- Northwest Lockheed L-188A Electra - "Tell City Crash" - 1960 Police documentary film from 1960
- Wind tunnel tests of NASA
- Lessons Learned , Federal Aviation Administration .
- Stuart Lee: Lockheed Electra: Killer Airliner
- Stuart Lee: Lockheed Electra: Killer Airliner (Part 2)
- Company history of the machine on planelogger.com .
Coordinates: 37 ° 54'40 " N , 86 ° 37'59" W.