Date: May 25, 1979
Type: DC-10-10
Registration: N110AA
Operator: American Airlines, Inc.
Where: Chicago-OUHare International Airport
Report No. NTSB-AAR-79-17
Report Date: December 21, 1979
Pages: 103

About 1504 c.d.t., May 25, 1979, American Airlines, Inc., Flight 191, a 
McDonnell-Douglas DC-10-10 aircraft, crashed into an open field just 
short of a trailer park about 4,600 ft northwest of the departure end of 
runway 32R at Chicago-O'Hare International Airport, Illinois.

Flight 191 was taking off from runway 32R. The weather was clear and the 
visibility was 15 miles. During the takeoff rotation, the left engine and 
pylon assembly and about 3 ft of the leading edge of the left wing 
separated from the aircraft and fell to the runway. Flight 191 continued 
to climb to about 325 ft above the ground and then began to roll to the 
left. The aircraft continued to roll to the left until the wings were 
past the vertical position, and during the roll, the aircraft's nose 
pitched down below the horizon.

Flight 191 crashed into the open field and the wreckage scattered into an 
adjacent trailer park. The aircraft was destroyed in the crash and 
subsequent fire.  Two hundred and seventy-one persons on board Flight 191 
were killed; two persons on the ground were killed, and two others were 
injured. An old aircraft hangar, several automobiles, and a mobile home 
were destroyed.

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 

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.