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Collin Fleck

John Schaefer

Human Factors in Flight

11/18/15

Delta Air Lines Flight 1141

On the morning of August 31st, 1988 at Dallas Ft. Worth International,

Delta Air Lines Flight 1141, a Boing 727-232 was preparing for departure to

Salt Lake City International Airport. On board were 101 passengers, and a

crew of seven including flight attendants Dixie Dunn, 56; Rosilyn Marr, 43;

Mary ONeill, 57; Diana George, 40; Flight Engineer Steven Judd, 31; First

Officer Gary Kirkland, 37; and Captain Larry Davis, 48. With a total of 108

persons aboard, the nearly fully loaded aircraft received clearance to push

back from its gate at 8:30 AM local time. Ground control then instructed

Flight 1141 to taxi to runway 18L, one of Dallas Ft. Worths seven runways,

for the quickest departure.

During the taxi to 18L, the flight experienced a delay across what is

known as the alpha-bridge at Dallas Ft. Worth, which is a bridge that

aircraft use to cross over a highway which runs through the airfield. During

the wait, one of the flight attendants on board entered the cockpit and began

a casual conversation with the pilots and flight engineer. After a fifteen to

twenty-minute wait, the aircraft was cleared to taxi the remainder of the way

to 18L. At approximately 8:57 AM, the aircraft preceding flight 1141, an

American Airlines DC-10 was given clearance to take off from 18L. Flight

1141 was told to taxi into takeoff position behind the DC-10 and hold for one
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minute to allow time for the wake turbulence to dissipate. The crew then

made a request for a two-minute wait instead, which was granted by Air

Traffic Control.
During the wait for the wake turbulence to clear, the conversation

between the pilots and flight attendant continued. Coincidentally, they

discussed the crash of Continental Airlines Flight 1713 which had taken place

the previous year in Denver. One of the causes of the accident was ruled by

the NTSB to be three minutes of non-pertinent social conversation before

takeoff. In the cockpit voice recordings of flight 1141, one of the pilots can be

heard explaining to the flight attendant that the crew of the Continental

Airlines flight were discussing the dating habits of one of their flight

attendants before they crashed. Another crew member on flight 1141 can

be heard making a joke that they should leave something for their wives

and children to listen to in case they were to crash as well.

After the conversation ends, one of the pilots sets the power and the

aircraft begins its takeoff roll down the runway. Up to this point, the takeoff

seemed routine. Call outs were made by one of the pilots that the engines

and airspeed looked good, but as the aircraft reached 80 knots and the

captain began to rotate, the crew realized something was wrong. What they

didnt realize was that their chat with the flight attendant during taxi and the

takeoff sequence had distracted them enough to neglect the procedure of

setting the slats and flaps to the correct configuration for takeoff.
As the main wheels left the ground, the plane reached critical angle of

attack without flaps and slats, and began to stall. The disrupted airflow over

the wings caused one or more of the engines to experience compressor stalls
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which deepened the severity of the situation. The lack of lift being produced

by the wings and the now insufficient thrust being produced by the engines

caused the aircraft to impact the ILS localizer antenna array, and then the

ground approximately 3200 feet from the end of the runway. The initial

impact and the subsequent fire resulted in a total of 14 deaths including two

of the flight attendants, and 12 passengers. Out of the 94 survivors, Captain

Davis, First Officer Kirkland, and the remaining two flight attendants were

seriously injured, Flight Engineer Judd and 49 other passengers received

minor injuries, and the remaining 18 passengers were uninjured.

After investigation, the NTSB ruled that the probable cause of the

accident was the failure of the flight crew to extend the flaps and slats to

proper takeoff configuration due to inadequate cockpit discipline. Another

factor that may have lead to the failure of the crew to configure the aircraft

properly was improper checklist usage. The NTSB accident report states that

the first officer was recorded responding to the captains challenge of setting

the flaps, but that there is no way of knowing if he actually looked down to

confirm that this action had been performed. The report states that It is not

uncommon for crewmembers to fall into a habit of answering to challenges

by rote with the normal response without actually observing the appropriate

indicator, light, or switch. The investigation also found that the aircrafts

takeoff warning system which is supposed to alert the pilots of an improper

takeoff configuration was inoperative. This may have been able to prevent

the accident, but it is no excuse for the flight crew to deviate from procedure

and incorrectly complete checklists.

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In my opinion, the primary human factors that played a roll in this

accident were the failure to comply with the Sterile Cockpit regulation, the

distractions resulting from the deviation from this regulation, and

complacency with regard to checklist completion. In addition to these

factors, I believe that the members of the crew in the cockpit during the

takeoff sequence missed the opportunity to realize the distractions that were

being created by the non-essential conversation and put an end to it.

The Sterile Cockpit Rule which applies to both pilots and flight

attendants was instated by the FAA in 1981, so it was nothing entirely new at

the time of the flight 1141 accident and should have been obeyed by the

entire crew. As time goes on, accidents such as this and the accident of

Continental Airlines Flight 1713 mentioned in the cockpit voice recorder

should become reminders to flight crews of the reasons that non-essential

activities are prohibited during taxi, takeoff, landing, and non-cruise flight

below 10,000 feet. They should also remind crews of how important it is to

adhere to procedure, avoid complacency in the cockpit by following

checklists in the correct manner, and to perform briefings at each stage of

the flight.
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Works Cited

National Transportation Safety Board. Aircraft Accident Report: Delta Airlines,

Inc., Boeing 727-232, N473DA, Dallas-Fort Worth International Airport, Texas,
August 31, 1988. 1989.
http://libraryonline.erau.edu/online-full-text/ntsb/aircraft-accident-
reports/AAR89-04.pdf. Visited Nov. 18, 2015.

Kilroy, Chris. Axelsson, Per. Special Reports: Delta Air Lines Flight 1141.
Airdisaster.com, visited Nov. 18, 2015

Miller, Laura. Metropolis Memories in the Wreckage. D Magazine, October

1989. Dmagazine.com. Visited Nov. 18, 2015.

Kolstad, James L. National Transportation Board Safety Recommendation,

Jan. 9, 1990.

Sterile Cockpit Rule, Wikipedia. Wikipedia.org. Visited Nov. 18 2015.