Thirty-five years ago, American Airlines flight 191 departed Chicago O’Hare for Los Angeles on a routine flight. Moments after takeoff, however, the DC-10 crashed, killing all 258 passengers and 13 crew on board. It still remains the deadliest aviation accident to occur on U.S. soil.
At 2:50PM CDT on May 25, 1979, American Airlines flight 191 pushed back from gate K5 with clear weather in the Chicago area and a 22 knot northeast wind. The aircraft began to take off of runway 32R/14L at 3:02PM CDT. However as the aircraft reached takeoff speed, the number one engine and its pylon assembly separated from the left wing which ripped a three-foot section of the leading edge with it, and it fell on the runway.
An American Airlines Maintenance Supervisor witnessed the event, and he explained that “as the aircraft got closer, I noticed what appeared to be vapor or smoke of some type coming from the leading edge of the wing and the No. 1 engine pylon. I noticed that the engine was bouncing up and down quite a bit and just about the time the aircraft got opposite my position and started rotation, the engine came off, went up over the top of the wing, and rolled back down onto the runway. Before going over the wing, it went forward and up just as if it had lift and was actually climbing. It didn’t strike the wing on its way down, rather the engine followed the clear path of the airflow of the wing, up and over the top of it, and then down below the tail. The aircraft continued a fairly normal climb until it started a turn to the left. And at that point, I thought they were going to come back to the airport.”
At the time of the problems occurring, the aircraft was already above V-1 speed which is the speed of no point of return. Now, the pilots were committed to the take off.
What happened next remains unclear. When the engine broke off, it cut off the power to the cockpit voice recorder. The last sounds were of the engine separating (which was a thumping noise) and First Officer Dillard exclaiming “Damn!”
ATC then offered AAL191 to return to the airport and that they lost an engine, but there was no response from the aircraft.
Meanwhile, several systems failed and were failing. The number one hydraulic system failed as it was powered by the number one engine, but it continued to operate as motor pumps mechanically connected it to hydraulic system three. However, hydraulic system three started leaking and was damaged, but according to the investigators, the pressure was maintained until impact.
A generator that was attached to the number one engine failed which caused many electrical systems to go offline. When this happened, the captain’s instruments and stick shaker all went offline. However, there was a button installed in the overhead panel which allows captains to restore power to their instruments, but the accident investigation report says the button was never used. There was a way for the flight engineer to turn on the backup power switch, but it would require the engineer to rotate his seat and stand up. Since the flight was only in their air for 50 seconds, officials say there would not have been sufficient time to react.
Officials say that it is possible the pilots may not have known that engine number one fell off since they could not have seen the wings.
Witnesses say that the aircraft did not fly above 300 feet, and they said they saw a white vapor trail of fuel and hydraulic fluid from the left wing.
Though, there is some discrepancy on witness accounts of the control of the aircraft. Some thought that the crew had successfully steered away from a trailer park near the impact point, and others claimed that all control was completely lost and they saw the aircraft bobbing up and down.
There were large sections of debris that destroyed five trailers and fell on several cars, and the aircraft crashed into an old aircraft hangar at the former site of Ravenswood Airport. Almost immediately after impact, the aircraft became a huge fireball which destroyed the aircraft, and there were no significant pieces of the aircraft’s fuselage remaining.
All 271 passengers and crew on board were killed instantly by the force of impact. Two employees at a nearby repair garage were killed, and two suffered severe burns.
The National Transportation Safety Board (NTSB) was tasked to determine what caused the engine to separate and why the airplane was unable to remain airborne on its two remaining engines. The aircraft should have been able to fly on two engines, but the DC-10 did not include a separate mechanism to lock the extended leading edge slats in place like other aircraft.
The findings of the investigation were released by the NTSB on December 21, 1979:
The National Transportation Safety Board determines that the probable cause of this accident was the asymmetrical stall and the ensuing roll of the aircraft because of the uncommanded retraction of the left wing outboard leading edge slats and the loss of stall warning and slat disagreement indication systems resulting from maintenance-induced damage leading to the separation of the No. 1 engine and pylon assembly at a critical point during takeoff. The separation resulted from damage by improper maintenance procedures which led to failure of the pylon structure.
Contributing to the cause of the accident were the vulnerability of the design of the pylon attach points to maintenance damage; the vulnerability of the design of the leading edge slat system to the damage which produced asymmetry; deficiencies in Federal Aviation Administration surveillance and reporting systems which failed to detect and prevent the use of improper maintenance procedures; deficiencies in the practices and communications among the operators, the manufacturer, and the FAA which failed to determine and disseminate the particulars regarding previous maintenance damage incidents; and the intolerance of prescribed operational procedures to this unique emergency.
Additionally, the NTSB said the damage to the left wing engine pylon had occurred during an earlier engine change at the American Airlines aircraft maintenance facility in Tulsa, Oklahoma, on March 29 and 30, 1979.
American Airlines was fined $500,000 for the accident because of improper maintenance procedures. However, the DC-10 was in the spot light.
Two weeks after AA191 crashed, the FAA suspended the type certificate for the DC-10 which grounded all DC-10s under its jurisdiction. Additionally, the FAA banned the DC-10 from U.S. airspace which was in place as the FAA investigated the crash of AA 191.
For one month, the DC-10 was grounded. Finally on July 13, the FAA permitted the DC-10 to fly in U.S. airspace and un-grounded the DC-10. But exactly six months after AA191 crashed, Air New Zealand flight 901 crashed when it hit a mountain, but human and environment factors caused the crash.
The DC-10 continued to have a negative reputation the aviation community. United Airlines flight 232 lost and engine and all flight controls. The aircraft crashed in a huge fireball, and there were 111 fatalities.
American Airlines retired its DC-10 fleet in 2000, and just recently, Biman Bangladesh Airlines operated the final DC-10 passenger flights.
For 32 years, families tried to build a permanent memorial for the victims, and finally, funding was obtained for a memorial in 2009 thanks to a two-year effort by a group of schoolchildren from Decatur Classical School. The memorial, a two-foot concave wall with interlocking bricks displaying the names of the crash victims, was formally dedicated in a ceremony on October 15, 2011
Airchive’s thoughts go out to all of the families of the passengers and crew who were on-board American flight 191 on May 25, 1979.