Based on the time since the last inspection of the jackscrew assembly, the NTSB determined that the acme-nut thread had deteriorated at 0.012 inches (0.30 mm) per 1000 flight‑hours, much faster than the expected wear of 0.001 inches (0.025 mm) per 1000 flight‑hours. Pieces of the airplane wreckage were found floating on and beneath the surface of the ocean. [1], End-play checks were conducted during a periodic comprehensive airframe overhaul process called a C‑check. As the airplane passed through 23,400 feet, the acme screw and nut jammed, preventing further movement of the horizontal stabilizer until the initial dive. Alaska 261 departed from Puerto Vallarta at 1:37 p.m. PST, and climbed to its intended cruising altitude of flight level 310 (31,000 ft). [1], Systemic problems were identified by the investigation in the FAA's oversight of maintenance programs, including inadequate staffing, its approval process of maintenance interval extensions, and the aircraft certification requirements. [1]:162–165, For this design component to be approved ("certified") by the FAA without any fail-safe provision, a failure had to be considered "extremely improbable". Over the next 3 to 4 seconds, the increasing angle-of-attack of the horizontal stabilizer and the increased elevator deflections would have in turn increased the tension loads on the acme screw, contributing to the motion of the acme screw upward through the acme nut. [18] One pilot radioed, "That plane has just started to do a big huge plunge." He is, uh, definitely in a nose down, uh, position, descending quite rapidly. A lead mechanic at Alaska Airlines' Oakland maintenance facility reported maintenance short comings to the FAA fifteen months prior to the crash, and was placed on paid leave. [26] In December 2001, federal prosecutors stated that they were not going to file criminal charges against Alaska Airlines. L'avion était un McDonnell Douglas MD-83, immatriculé N963AS, numéro de série 53077, construit en 1992. Also contributing to the accident was the absence on the McDonnell Douglas MD-80 of a fail-safe mechanism to prevent the catastrophic effects of total acme nut thread loss. "[18] ATC then tried to contact the plane. [40][41], As of December 2020, Flight 261 no longer exists, and Alaska Airlines no longer operates the Puerto Vallarta–San Francisco–Seattle/Tacoma route. At 1619:24, the first officer asked, "you feel that?" As it turns out, over two years prior, he had ordered the horizontal stabilizer jack screw on this aircraft be replaced. Both pilots struggled together to regain control of the aircraft, and only by pulling with 130 to 140 pounds (580 to 620 Newtons) on the controls did the flight crew stop the 6,000 ft/min (1,800 m/min) descent of the aircraft and stabilize the MD-83 at approximately 24,400 ft (7,400 m). This and other evidence suggested to the NTSB that "the SFO mechanic who was responsible for lubricating the jackscrew assembly in September 1999 did not adequately perform the task". [5] Captain Edward "Ted" Thompson, 53, had accrued 17,750 flight hours, and had more than 4,000 hours experience flying MD-80s. Over the course of the investigation, the NTSB considered a number of potential reasons for the substantial amount of deterioration of the nut thread on the jackscrew assembly, including the substitution by Alaska Airlines (with the approval of the aircraft manufacturer McDonnell Douglas) of Aeroshell 33 grease instead of the previously approved lubricant, Mobilgrease 28. [33] Candy Hatcher of the Seattle Post-Intelligencer said: "Many lost faith in Alaska Airlines, a homegrown company that had taken pride in its safety record and billed itself as a family airline. [1], In 2001, the National Aeronautics and Space Administration (NASA) recognized the risk to its hardware (such as the Space Shuttle) attendant upon use of similar jackscrews. [1]:11 Neither pilot had been involved in an accident or incident prior to the crash. The next few seconds of FDR data indicated a maximum airplane-nose-down pitch rate of nearly 25° per second. Alaska Airlines Flight 261 Flight Crew who "tragically" departed us on Monday January 31, 2000 about 2.7 miles north of Anacapa Island in Southern California. [1] The captain replied: "I need to get down to about ten, change my configuration, make sure I can control the jet and I'd like to do that out here over the bay if I may. Alaska Airlines Flight 261. [1], Due to the extreme impact forces, only a few bodies were found intact,[5] and none were visually identifiable. [9], At least 35 occupants of Flight 261 were connected in some manner with Alaska Airlines or its sister carrier Horizon Air, including twelve actual employees,[10] leading many of the airlines' personnel to mourn for those lost in the crash. 1 Circonstances de l'accident; 2 Enquête; 3 Pilotes; 4 Suite; 5 Médias; 6 Références; 7 Articles connexes; 8 Liens externes; Circonstances de l'accident. "[18] Although the CVR captured the co-pilot saying, "mayday," no radio communications were received from the flight crew during the final event. The aircraft designers assumed that at least one set of threads would always be present to carry the loads placed on it, therefore the effects of catastrophic failure of this system were not considered, and no "fail-safe" provisions were needed. 0:10. About 5 seconds later, the CVR recorded the sound of a series of at least four distinct "thumps." [1], During this time, the flight crew had several discussions with the company dispatcher about whether to divert to LAX, or continue on as planned to SFO. More than half of these were directly related to jackscrew lubrication and end-play measurement. Bouquets of flowers started arriving at the company's headquarters in SeaTac, Washington, the day after the crash. [1] Insufficient lubrication of the components was also considered as a reason for the wear. At 1619:43, the first officer stated, "mayday," but did not make a radio transmission. As the jackscrew rotates, it moves up or down through the (fixed) acme nut, and this linear motion moves the horizontal stabilizer for the trim system. At their cruising altitude and speed, the position of the jammed stabilizer required the pilots to pull on their yokes with approximately 10 pounds (44 N) of force to keep level. See, Licenciado Gustavo Díaz Ordaz International Airport, Naval Construction Battalion Center Port Hueneme, "Aircraft Accident Report, Loss of Control and Impact with Pacific Ocean Alaska Airlines Flight 261 McDonnell Douglas MD-83, N963AS About 2.7 Miles [4.3 km] North of Anacapa Island, California, January 31, 2000", Alaska Airlines Flight 261: Searchers Hold Out Hope for Possible Survivors; Crash Takes Heavy Toll on Airlines Employees' Families, "Alaska Airlines jet crashes into Pacific", "Passengers and Crew Members on Alaska Airlines Flight 261", "(Essay 2958) Alaska Flight 261 bound for Seattle crashes into the Pacific Ocean on January 31, 2000", "Remembering Morris Thompson 20 years later", "Flight 261 Special Report: Alaska Airlines Names Aviation Experts To Conduct Safety Audit", "The anger and the grief linger one year later", "Fate Leads An Airline To Grieve For Itself", "THE CRASH OF FLIGHT 261: For Airline, Loss Feels Like Deaths in Family", "Names of those aboard Alaska Airlines Flight 261", "Transcript of Proceedings: Abstract of Aviation Accident Report: Alaska Airlines Flight 261, MD‑83, N963AS, Pacific Ocean about 2.7 Miles [4.3 km ] North of Anacapa Island, California, January 31, 2000, NTSB/AAR‑02/01", "Alaska Airlines Flight 261 – 31 JAN 2000 – Relevant parts of ATC transcript", "Tape replays plane's last chilling minutes", "NASA says it has a better jackscrew; others aren't convinced", "Systems Thinking 1.0 and Systems Thinking 2.0: Complexity science and a new conception of "cause, Alaska Airlines maintenance records raise new questions, No criminal charges against Alaska; airline settles with whistle-blower, "Alaska Airlines copes with 'saddest, most tragic day, "Port Hueneme, CA – Official Website – Alaska Air Flight 261 Memorial Sundial", "Memorials quieter today, but Flight 261 grief still hurts", "20 years after Alaska Airlines Flight 261 crash, loved ones still gather to grieve", "Pilots honored for heroism during crisis", "Ted Thompson/Bill Tansky Scholarship Fund", "All but one suit settled in Flight 261 crash", "Father settles lawsuit in Alaska Air crash to avert playing of tape", "Seattle still struggling to make sense of the Flight 261 tragedy", "Quest for truth proves lawyer's integrity", "Nigerian Advance Fee Scam Customized for Alaska: Morris Thompson variation could be taste of ploys to come", "Latest e-mail uses Alaska Airlines crash victims to scam", "AS203 (ASA203) Alaska Airlines Flight Tracking and History", "AS373 (ASA373) Alaska Airlines Flight Tracking and History", "Alaska Airlines Completes Transition To All-Boeing Fleet", Cockpit voice recorder transcript and accident summary, Navy expands search for debris at Alaska Airlines Flight 261 crash scene, Applying Lessons Learned from Accidents, Alaska Airlines Flight 261, Federal Aviation Administration – Lessons Learned Home: Alaska Airlines Flight 261, https://en.wikipedia.org/w/index.php?title=Alaska_Airlines_Flight_261&oldid=1009081250, Airliner accidents and incidents caused by maintenance errors, Aviation accidents and incidents in the United States in 2000, Accidents and incidents involving the McDonnell Douglas MD-83, Airliner accidents and incidents in California, Aviation accidents and incidents caused by loss of control, Short description is different from Wikidata, Creative Commons Attribution-ShareAlike License, Cynthia Oti, an investment broker and financial talk show host at San Francisco's. [1] Maintenance procedures such as lubrication and end-play checks were to catch any excessive wear before it progressed to a point of failure of the system. However, several factors led the Board to question "the depth and effectiveness of Alaska Airlines corrective actions" and "the overall adequacy of Alaska Airlines' maintenance program". ", The aircraft involved in the accident was a McDonnell-Douglas MD-83, serial number 53077, and registered as N963AS. Testimony from an FAA inspector regarding an extension granted in 1996 was that Alaska Airlines submitted documentation from McDonnell Douglas as justification for their extension. [1], Beginning at 16:19 (00:19 UTC), the CVR recorded the sounds of at least four distinct "thumps," followed 17 seconds later by an "extremely loud noise," as the overstrained jackscrew assembly failed completely and the jackscrew separated from the acme nut holding it in place. Alaska Airlines Flight 261 was a scheduled international passenger flight from Licenciado Gustavo Díaz Ordaz International Airport in Puerto Vallarta, Jalisco, Mexico, to Seattle–Tacoma International Airport in Seattle, Washington, United States, with an intermediate stop at San Francisco International Airport in San Francisco, California. The 2 pilots, 3 cabin crewmembers, and 83 passengers on board were killed, and the airplane was destroyed by impact forces. [1]:195–197, At 16:09 (00:09 UTC), the flight crew successfully unjammed the horizontal stabilizer with the primary trim system. This page was last edited on 26 February 2021, at 16:44. In NTSB board member John J. Goglia's statement for the final report, which was concurred with by the other three board members, he wrote: This is a maintenance accident.
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