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 one of its engines detached. The tragedy resulted in 273 fatalities, but how exactly did it happen? Let’s take a look back in time to examine the causes of the crash.

The flight and aircraft involved

American Airlines Flight 191 was a scheduled service that originated at Chicago O’Hare International Airport (ORD) in the US federal state of Illinois. Its destination was the Californian hub of Los Angeles International (LAX).

The Aviation Safety Network notes that, on May 25th, 1979, this domestic flight was operated by N110AA; a McDonnell Douglas DC-10-10 wore this registration at the time. Data from ATDB.aero shows that this three-engined widebody aircraft was delivered to American Airlines in February 1972.

Engine separation

While the aircraft departed 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 backward over the top of the wing before landing behind the departing plane on Chicago O’Hare’s runway 32R.

Following this stall and loss of control, American Airlines Flight 191 crashed just 1,400 meters (4,600 feet) beyond the end of the runway. Tragically, all 258 passengers and 13 crew members died in the crash. Two employees at a garage in the vicinity of the crash site also perished, bringing the total death toll to 273.

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 (91.5 meters), 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, whereafter it crashed to the ground in a fireball.

Why did the engine detach?

A vital part of the investigation into the crash was determining what caused the engine to detach in the first place. Several witnesses to the accident 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.

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 Airlines’ maintenance engineers had removed the engine and pylon from the wing as a single unit.

This contradicted McDonnell Douglas’s guidance, which dictated that engineers should remove each component separately. American Airlines’ method instead relied on supporting the engine and pylon assembly on a forklift. However, N110AA’s left engine was damaged by being jammed against the wing after a slight loss of hydraulic pressure to the forklift during a shift change.

Photo: FAA

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, which impacted the DC-10’s reputation. The NTSB investigation into the crash was one of its most extensive and held the FAA partially responsible for its “failure to detect and prevent the use of improper maintenance procedures,” as well as poor communication between the FAA, operator, and manufacturer.

Subsequent DC-10 grounding and legacy

Indeed, the McDonnell Douglas DC-10 had already been involved in two other significant 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.

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These occurrences 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 and banned foreign DC-10s from US airspace. The grounding period lasted just over a month.

The FAA eventually restored the McDonnell Douglas 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. However, much like McDonnell Douglas’s other widebody trijet, the MD-11, the DC-10 has ultimately proven to be more popular as a freighter in its later years.

The route today

With Chicago O’Hare and Los Angeles International being two key US hubs, it goes without saying that American Airlines still connects the two today. However, it appears to have retired flight number AA191, with FlightAware showing that it was last used in 2014 on a route to Milwaukee. Nowadays, American primarily deploys Boeing 737 aircraft on this domestic cross-country route.

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