Douglas DC-9

Wrong approach configuration on part of the flying crew.

It was determined that the aircraft encountered windshear on short final with wind from 240° to 320° gusting 26 to 47 knots. The copilot who was at controls at this time was not sufficiently experienced according to the operator operational procedures. Poor supervision on part of the captain and a too late recovery were considered as contributing factors.

Due to lack of evidences, the exact cause of the accident could not be determined with certainty.

It was determined that on short final, during the last segment, the copilot inadvertently extended the spoilers, causing the aircraft to enter a rapid descent until it impacted the runway surface with a positive acceleration that exceeded its certification. Presence of corrosion in the wing's root was reported as a contributing factor. Lack of crew coordination and poor planned approach also contributed to the mishap.

The aircraft encountered a sudden wind gust during landing flare, which resulted in a hard landing.

Wrong approach configuration on part of the flying crew who decided to continue the descent while the aircraft was unstable and misaligned with the runway. The following contributing factors were reported:
- Failure of the crew to initiate a go-around procedure,
- Unstabilized approach,
- Excessive approach speed,
- Touchdown completed in a nose-down attitude,
- Poor crew coordination,
- Poor weather conditions with thunderstorm activity.

The accident was the consequence of the combination of the following factors:
- The crew failed to prepare the flight according to published procedures and failed to follow various checklists,
- The crew failed to realize he was following a wrong heading after takeoff and failed to proceed to the en-route checks as required,
- The crew was distracted by conversations with a third person who was seating on the jumpseat all flight,
- The crew failed to supervise the flight according to standard operations,
- Poor crew coordination,
- Lack of discipline,
- At the time of impact, the aircraft was flying under VFR mode in IMC conditions,
- Poor visibility due to low clouds surroundings the mountains struck by the airplane.

The failure of the flightcrew to detect and remove ice contamination on the airplane's wings, which was largely a result of a lack of appropriate response by the federal aviation administration, Douglas aircraft company, and ryan international airlines to the known critical effect that a minute amount of contamination has on the stall characteristics of the DC-9 series 10 airplane. The ice contamination led to wing stall and loss of control during the attempted takeoff.

Lack of proper crew coordination, including virtual reversal of roles by the DC-9 pilots, which led to their failure to stop taxiing and alert ground controller of their positional uncertainty in a timely manner before and after intruding onto the active runway. Contributing to cause of accident were:
- Deficiencies in ATC services provided by Detroit tower, including failure of ground control to take timely action to alert local controller to possible runway incursion, inadequate visibility observation, failure to use progressive taxi instructions low-visibility conditions, and issuance of inappropriate and confusing taxi instructions compounded by inadequate backup supervision for level of experience of staff on duty;
- Deficiencies in surface markings, signage and lighting at airport and failure of FAA surveillance to detect or correct any of these deficiencies;
- Failure of Northwest Airlines to provide adequate cockpit resource management training to line aircrews. Contributing to fatalities was inoperability of DC-9 internal tailcone release mechanism. Contributing to number and severity of injuries was failure of crew of DC-9 to properly execute the passenger evacuation.