What Caused The Crash Of American Airlines Flight 191?

The crash of American Airlines flight 191 near Chicago, Illinois in May 1979 remains one of the deadliest accidents in aviation history. The Los Angeles-bound flight, operated by a McDonnell Douglas DC-10, crashed just after takeoff after an engine became detached. The tragedy resulted in 273 fatalities, but how exactly did it happen?

American Airlines McDonnell Douglas DC-10
The aircraft involved bore the registration N110AA. Photo: Jon Proctor via Wikimedia Commons

What happened?

American Airlines flight 191 was a scheduled service from Chicago O’Hare (ORD) to Los Angeles International (LAX). On May 25th, 1979, it was operated by N110AA. This registration was worn by a seven-year-old McDonnell Douglas DC-10 at the time. Planespotters.net reports that this aircraft was delivered brand-new to American in February 1972.

While the aircraft was departing for California, its number one engine (on the left-hand or port side) detached from its wing. The separation of the engine and its pylon assembly also caused a one-meter section of the wing’s leading edge to be ripped away. These components rolled backwards over the top of the wing before landing behind the plane on the runway.

What Caused The Crash Of American Airlines Flight 191?
American operated a total of 66 DC-10s between 1971 and 2003. Photo: Dean Morley via Flickr

Following this stall and loss of control, American Airlines flight 191 crashed just 1,400 meters beyond the runway. Tragically, all 258 passengers and 13 crew members died as a result of the crash, as well as two employees at a garage in the vicinity of the crash site.

The loss of the engine damaged several of the aircraft’s hydraulic systems. Although it was able to climb to a height of around 300 feet, the crew soon lost control of the aircraft due to these failures. The left wing eventually experienced an aerodynamic stall, causing the plane to roll to the left at an angle of 112 degrees.

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Why did the engine detach?

A key part of the investigation into the crash was determining what caused the engine to detach in the first place. Witnesses stated that the aircraft had not struck an object during its takeoff roll that might have caused the separation. As such, investigators instead had to consider the possibility of a structural failure, and what might have caused this to occur.

FAA DC-10 Engine Diagram
An FAA diagram showing the engine’s various mounts and attach points. Image: FAA via Wikimedia Commons

The NTSB eventually found that the engine’s pylon assembly had been damaged during maintenance around two months beforehand. Its investigation showed that, in an attempt to save time, American’s engineers had removed the engine and pylon from the wing as a single unit. This contradicted McDonnell Douglas’s guidance to do each component separately.

American’s method relied on supporting the engine and pylon assembly on a forklift truck. However, in the case of N110AA’s left engine, it was damaged by being jammed against the wing after a slight loss of hydraulic pressure to the forklift during a shift change. This damage later developed into fatigue cracking, which worsened every time the plane took off or landed. This came to a head on May 25th, causing the engine separation and subsequent crash.

American Airlines McDonnell Douglas DC-10
American marketed the DC-10 as the ‘LuxuryLiner.’ Photo: Aero Icarus via Wikimedia Commons

Subsequent DC-10 grounding and legacy

The DC-10 had already been involved in two other major accidents earlier in the decade. These occurrences involved American Airlines flight 96 (1972) and Turkish Airlines flight 981 (1974), and both featured cargo door failures. While the former had no fatalities, all 346 occupants in the latter accident perished, making it the deadliest crash not involving a 747.

These occurrences had dented public confidence in the aircraft, and the crash of American Airlines flight 191 only amplified this sentiment. As such, the Federal Aviation Administration (FAA) elected to suspend the DC-10’s type certificate on June 6th, 1979. This ruling grounded all US-based DC-10s, as well as banning foreign DC-10s from US airspace.

Lufthansa Cargo MD-11 Frankfurt Getty
Like its successor, the MD-11 as pictured here, the DC-10 was more popular as a freighter in its later years. Photo: Getty Images

The grounding period lasted just over a month. The FAA eventually restored the DC-10’s type certificate on July 13th, 1979. American Airlines flight 191 was not the last accident involving the aircraft, but those that followed were not attributed to similar causes.

Nonetheless, the crash (as well as the 1979-1982 US recession) caused order numbers to fall, particularly among passenger carriers. Much like McDonnell Douglas’s other widebody trijet, the MD-11, the DC-10 ultimately proved more popular as a freighter in its later years.

Did you know about the crash of American Airlines flight 191? Have you ever flown on a DC-10, either at American or another carrier? Let us know your thoughts and experiences in the comments.