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File:Alitalia.md82.i-datu.arp.jpg, similar to the aircraft involved in the accident]]

The aircraft involved in the accident was a McDonnell Douglas MD-82, registration N312RC. Manufactured in 1981, the aircraft had been operated by Republic Airlines until the company was acquired by Northwest AirlinesNTSB 1980, p. 6. in 1986.{{cite news|title=Northwest Orient will buy Republic to become 3rd largest U.S. airlines|url=http://news.google.com/newspapers?id=TJ8oAAAAIBAJ&sjid=D4QDAAAAIBAJ&pg=7034,3475617&dq=northwest+buys+republic&hl=en|accessdate=January 8, 2011|newspaper=Deseret News|date=January 24, 1986}} The MD-82 is a twin-engine, medium-range, single-aisle commercial jet airliner, lengthened and updated from the McDonnell Douglas DC-9.{{cite web|title=Northwest Airlines Flight 255|url=http://www.check-six.com/Crash_Sites/NWA_Flt_255.htm|publisher=Check-Six.com|accessdate=January 11, 2011}}

The pilot, age 57, had worked for 31 years with three companies, and was certified to fly seven different aircraft, including the Douglas DC-3 and Boeing 757. Pilots and first officers who had worked with him told the NTSB he was, according to the accident report, "a competent and capable pilot". The first officer, age 35, was described by pilots he had flown with as average or above average. In interviews with the NTSB, pilots described him as a "competent pilot" who was “easy to work with".

On August 16, 1987, the aircraft departed Saginaw, Michigan, as Northwest Airlines Flight 255, for Santa Ana, California, with two stopovers between, the first in Detroit, Michigan, and the second in Phoenix, Arizona. The aircraft departed Saginaw for the first leg of the flight at 18:53 Eastern Daylight Time (EDT){{#tag:ref|All times mentioned in this article are Eastern Daylight Time, UTC-4, unless otherwise noted.|group=note}}, and arrived at Detroit Metropolitan Wayne County Airport, Detroit, for the first stopover at 19:42.NTSB 1980, p. 1. At the airport, the weather was poor; according to the accident report the airport was "covered by thunderstorms with very heavy rain showers and thunderstorms that were increasing in intensity."NTSB 1980, p. 15. Pilots had reported windshear at the airport 30 minutes prior to the accident.NTSB 1980, p. 48.

The aircraft left the gate at approximately 20:32, with 149 passengers and six crew members on board the McDonnell Douglas airliner. The flight crew completed the "before start" checklist and then started up the engines. The flight plan called for the aircraft to take off from either runway 21R or 21L, but air traffic control (ATC) ordered the flight crew to use runway 3C, the shortest of three available runways.NTSB 1980, p. 3.

The flight crew missed a turning during taxiing, and they had to change radio frequencies to orientate themselves with their location; ATC gave them directions to runway 3C. At 20:44, ATC cleared the aircraft for take-off. Engine power was applied, but during the take-off roll the flight crew were unable to engage the autothrottle. According to the NTSB accident report, the take-off roll was "longer than that normally made by similar airplanes." Witnesses also said the aircraft "rotated to a higher pitch angle" than similar aircraft, and the tail of the aircraft almost touched the runway.NTSB 1980, p. 4. The first officer called 100 knots, and then for the aircraft to rotate. Four seconds later, the stick shaker stall warning activated, and continued to operate until the end of the cockpit voice recorder (CVR) recording.

When the aicraft became airborne, it began to roll from side to side, before the left wing struck a light pole. The outer section of the left wing sheared off from the remaining section of wing, rupturing the left wing fuel tank. The fuel ignited and the left wing trailed flames. The aircraft continued to roll left to right before it impacted with a second light pole, and then struck the roof of a car rental building at a 90 degree angle, with the left wing towards the ground. The aircraft continued forward before it struck a road outside the perimeter of the airport. The NTSB report stated, "The airplane continued to slide along the road, struck a railroad embankment, and disintegrated as it slid along the ground. Fires erupted in airplane components scattered along the wreckage path."

File:Wing.slat.600pix.jpg and slats of an aircraft.]]

During take-off and landing the velocity of an aircraft is relatively low, and therefore the lift must be higher. Modern commercial aircraft feature devices, flaps and slats, to increase the length of the wings during take-off and landing, increasing lift. Flaps are located on the trailing edge of the aircraft, and slats are located on the leading edge. Both devices can be moved by a lever in the cockpit of the aircraft aft or forward to provide more or less lift.{{cite web|title=Flaps and Slats|url=http://www.grc.nasa.gov/WWW/K-12/airplane/flap.html|publisher=NASA|accessdate=January 15, 2011}} Flaps and slats must be deployed during take-off or the aircraft will likely not have enough lift to leave the runway.{{cite web|title=Spanair - MD-82 Madrid, Spain 20th August, 2008|url=http://www.1001crash.com/index-page-description-accident-MD82_Spannair-lg-2-crash-212.html|publisher=1001 Crash|accessdate=May 7, 2011}}

Investigators examined the wreckage of the aircraft, and found evidence to suggest the flaps and slats were both retracted. In the cockpit, the flap handle was found to be in the "retracted" position. The NTSB also found a detent pin in the flap handle had made an indentation in the side of the flaps lever module; the pin likely created the mark when the aircraft impacted with the ground. The setting of the flap handle, location of the pin in the lever and the location of the indentation in the side of the module indicated the flaps lever was in the "retracted" position at the time of impact, indicating the flaps were retracted when the aircraft crashed.NTSB 1980, p. 51. Additionally, they examined the curved tracks in the wing which changed the positions of the flaps, and concluded the flaps were in the retracted position at the time of the accident.NTSB 1980, p. 50.

The NTSB also examined the positions of the slats on the aircraft when the accident occurred. The cables which controlled the position of the slats on the left wing were sheared when the aircraft struck the light pole, and from their position it was determined the leading edge slats were also retracted. Although two pilots in another aircraft stated the flaps and slats on Northwest 255 were extended, the NTSB found the light conditions at the time may have mislead them. Investigators concluded the aircraft did not have enough lift to climb away from the runway because the flaps and slats were not deployed during the take-off sequence.NTSB 1980, p. 52.

The flaps and slats are the first item on the "Taxi" checklist, a series of procedures which a flight crew must carry out before they begin the take-off roll. When investigators reviewed the CVR tape, they found the flight crew had not carried out the checklist, and thus not deployed either device. "This item was not performed, and the flightcrew did not discover that the airplane was configured improperly for takeoff," the NTSB report found. The omission of the "Taxi" checklist also explained the problem the crew experienced when they were unable to engage the autothrottle system during the takeoff roll—this occurred because they had not put the flight computer into takeoff mode, another item called for on the checklist. The final report found, "Once the takeoff began, however, there was little chance they would detect any of the visual cues ... that might have alerted them to the fact that the airplane was not configured properly."NTSB 1980, p. 56.

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• {{cite book |title=Aircraft Accident Report: Northwest Airlines, Inc. McDonnell Douglas DC-9-82, N312RC|last= |first= |authorlink= |coauthors= |year=1988 |publisher=National Transportation Safety Board |location= |isbn= |page= |pages= |url=http://libraryonline.erau.edu/online-full-text/ntsb/aircraft-accident-reports/AAR88-05.pdf |accessdate=January 9, 2011}}

{{Aviation incidents and accidents in 1987}}

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