Braniff International Airways Flight 542

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Braniff International Airways Flight 542
Lockheed L-188 Electra, Braniff International Airways JP6982155.jpg

An identical Lockheed L-188 Electra from Braniff International Airways
Accident summary
Accident type Structural failure
place Leon County , near Buffalo , Texas , United StatesUnited States 49United States 
date September 29, 1959
Fatalities 34
Survivors 0
Aircraft
Aircraft type United States 49United States Lockheed L-188 Electra
operator United States 49United States Braniff International Airways
Mark United States 49United States N9705C
Departure airport Houston International Airport , Houston , Texas United StatesUnited States 49United States 
1. Stopover Dallas Love Field , Dallas , Texas United StatesUnited States 49United States 
2. Stopover Washington National Airport , Arlington , Virginia , United StatesUnited States 49United States 
Destination airport LaGuardia Airport , New York City , New York United StatesUnited States 49United States 
Passengers 28
crew 6th
Lists of aviation accidents

On the Braniff International Airways flight 542 an accident on September 29, 1959 Lockheed L-188 Electra of Braniff International Airways after the machine was broken apart in the air. All 34 occupants of the machine were killed in the accident. The cause of the accident could only be determined with the investigation into the crash of another Lockheed L-188 Electra on Northwest Airlines Flight 710 .

plane

The aircraft that crashed was a Lockheed L-188 Electra with the serial number 1090, which made its maiden flight on September 4, 1959 and sent it to Braniff International for the first time on September 18, just eleven days before its crash, with the aircraft registration number N9705C Airways was delivered. 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 132 operating hours.

Flight history

The nocturnal domestic flight with flight number 542 was supposed to lead from Houston International Airport to LaGuardia Airport , stopovers were planned at Dallas Love Field and Washington National Airport . Before departure, work had to be carried out on the generator of engine no. 3, which delayed departure. The plane rolled off the gate in Houston at 10:37 p.m. local time, 22 minutes late. The go-ahead was given at 10:40 p.m., and the machine took off at 10:44 p.m. The first flight segment to Dallas should take 41 minutes. Air traffic control in Houston gave clearance to climb to 9000 feet (approx. 2740 meters) and instructed the crew to report to air traffic control in San Antonio after flying over the "Gulf Coast" marker.

The crew radioed the Braniff Airways communications center at 10:51 p.m. and 10:52 p.m., and shortly thereafter, as instructed, to San Antonio air traffic control, which cleared a climb from 9,000 feet to 15,000 feet and the crew instructed to report to Fort Worth Air Traffic Control.

the accident

Shortly after the radio communication with air traffic control in San Antonio, the pilots reported to the Braniff Airways communications center at 11:07 p.m. and stated that their aircraft needed maintenance. This was the last radio message from the crew.

The machine broke apart 3.8 miles (approximately 6.1 km) southeast of Buffalo, Texas at around 11:09 p.m. There was a structural failure of the left wing. The machine fell to the ground. All 34 inmates were killed. At the time of the crash, there were no other flying objects in the area.

Accident investigation

Since no flight data recorders were installed in aircraft at the time of the accident, determining the cause of the crash turned out to be difficult. The investigation was conducted by the Civil Aeronautics Board (CAB).

Much of the wreckage of the machine was in a potato field. The left wing was found one mile (1.6 km) away, with a widely scattered field of debris in between. The distance from the first debris finds along the flight route to the impact crater of the aircraft nose was 13,900 feet (approx. 4.3 km). After interviewing several eyewitnesses and inspecting the debris field, investigators concluded that the structural failure had started in the area of ​​the left wing. It was found that the structural failure was caused by flutter. The machine then broke apart in the air into several large parts. The debris was particularly concentrated at three points - the impact crater of the aircraft nose, the impact crater of the midsection, and the point where the tail of the aircraft hit. The aircraft nose impact crater was about 4 feet deep and formed the furthest eastward point of the debris field. The center section impact crater was 200 feet (approximately 60 meters) away and the aft section was an additional 250 feet (approximately 75 meters) away.

The degree of destruction was enormous, only a few components were easily identifiable. Since there had been fires in the area of ​​the impact craters after the impact, mechanical components were destroyed so that the investigators could not subject them to functional tests.

Investigators concluded from their investigations that the accident was caused by a flutter, known as vortex mode, in which the vibrations of the engines are transmitted to the aircraft structure. The exact cause of the vibration transmission remained unclear at first, and the investigation stalled.

Another incident in March 1960

On March 17, 1960, another Northwest Airlines Lockheed L-188 Electra crashed on Northwest Airlines flight 710 after the machine broke apart in the air. In this case, the material failure could also be traced back to flutter. The investigators also found that this was caused by a material weakness in the area of ​​an engine pylon. The investigators described the phenomenon as vortex mode, but initially could not understand the cause of the structural weakening. In the course of the investigations it was found that a hard touchdown had resulted in an unnoticed weakening of the engine pylon, which resulted in the flutter. Wind tunnel tests carried out at NASA with a model of a Lockheed Electra on a scale of 1: 8 that had been specially made for this purpose, it was possible to prove that structural failure could occur under the calculated parameters. On the test machine, the right wing including both engines broke off.

Final report

The findings from the investigation into the accident on Northwest Airlines flight 710 could also be applied to the crash of the Braniff machine. The investigators of the CAB concluded that structural damage to the engine pylon had also occurred on this machine during an earlier hard landing or a similar maneuver, which resulted in vibrations being transmitted to the wing structure and ultimately led to the wing and the engines being torn off. The final report was published on April 28, 1961.

consequences

As a result of the investigation results, Lockheed changed the design of the engine nacelles and pylons so that vortex mode scenarios could no longer occur. Extensive reinforcements were made to the engine nacelles and wing structure of all aircraft. There have been no other incidents of this type with the Lockheed L-188 Electra since then.

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