Alaska Airlines Flight 261

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 near Seattle, Washington, United States, with an intermediate stop at San Francisco International Airport in San Francisco, California. On January 31, 2000, the McDonnell Douglas MD-83 operating the flight crashed into the Pacific Ocean roughly 2.7 miles (4.3 km; 2.3 nmi) north of Anacapa Island, California, following a catastrophic loss of pitch control, while attempting to divert to Los Angeles International Airport. The accident killed all 88 on board – two pilots, three cabin crew members, and 83 passengers.

The subsequent investigation by the National Transportation Safety Board (NTSB) determined that inadequate maintenance led to excessive wear and eventual failure of a critical flight control system during flight. The probable cause was stated to be "a loss of airplane pitch control resulting from the in-flight failure of the horizontal stabilizer trim system jackscrew assembly's Acme nut threads." For their efforts to save the plane, both pilots were posthumously awarded the Air Line Pilots Association Gold Medal for Heroism.

Accident flight

Alaska Airlines Flight 261 departed from Puerto Vallarta's Licenciado Gustavo Díaz Ordaz International Airport at 13:37 PST (21:37 UTC), and climbed to its intended cruising altitude of flight level 310 (31000 ft). The plane was scheduled to land at San Francisco International Airport (SFO) less than 4 hours later. Sometime before 15:49 (23:49 UTC), the flight crew contacted the airline's dispatch and maintenance-control facilities in SeaTac, Washington, on a company radio frequency shared with operations and maintenance facilities at Los Angeles International Airport (LAX), to discuss a jammed horizontal stabilizer and a possible diversion to LAX. The jammed stabilizer prevented the operation of the trim system, which would normally make slight adjustments to the flight control surfaces to keep the plane stable in flight. At their cruising altitude and speed, the position of the jammed stabilizer required the pilots to pull on their yokes with about 10 lbf of force to keep level. Neither the flight crew nor company maintenance could determine the cause of the jam. Repeated attempts to overcome the jam with the primary and alternate trim systems were unsuccessful.

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. Ultimately, the pilots chose to divert. Later, the NTSB found that while "the flight crew's decision to divert the flight to Los Angeles... was prudent and appropriate," "Alaska Airlines dispatch personnel appear to have attempted to influence the flight crew to continue to San Francisco... instead of diverting to Los Angeles." Cockpit voice recorder (CVR) transcripts indicate that the dispatcher was concerned about the effect on the schedule ("flow"), should the flight divert.

At 16:09 (00:09 UTC), the flight crew successfully used the primary trim system to unjam the stuck horizontal stabilizer. Upon being freed, however, it quickly moved to an extreme "nose-down" position, forcing the aircraft into a nosedive. The plane dropped from about 31,050 ft to between 23,000 and 24,000 ft in around 80 seconds. Both pilots struggled together to regain control of the aircraft, and only by pulling with 130 to 140 lbf on the controls did the flight crew stop the 6,000 ft/min descent of the aircraft, and stabilize the MD-83 at roughly 24,400 ft.

Alaska 261 informed air traffic control (ATC) of their control problems. After the flight crew stated their intention to land at LAX, ATC asked whether they wanted to proceed to a lower altitude in preparation for the approach. 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." Later, during the public hearings into the accident, the request by the pilot not to fly over populated areas was mentioned. During this time, the flight crew considered, and rejected, any further attempts to correct the runaway trim. They descended to a lower altitude, and started to configure the aircraft for landing at LAX.

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. As a result, the horizontal stabilizer failed at 17800 ft, and the aircraft rapidly pitched over into a dive while rolling to the left. The crippled plane had been given a block altitude, and several aircraft in the vicinity had been alerted by ATC to maintain visual contact with the stricken jet. These aircraft immediately contacted the controller. One pilot radioed, "That plane has just started to do a big huge plunge." Another reported, "Yes sir, ah, I concur. He is, uh, definitely in a nose down, uh, position, descending quite rapidly." ATC then tried to contact the plane. The crew of a SkyWest airliner reported, "He's, uh, definitely out of control." Although the CVR captured the co-pilot saying "mayday," no radio communications were received from the flight crew during the final event.

The CVR transcript reveals the pilots' constant attempts for the duration of the dive to regain control of the aircraft. After the jackscrew failed, the plane pitched –70° and was rolling over to the left. Performing an upset recovery maneuver, the captain commanded to "push and roll, push and roll," managing to increase the pitch to –28°, he stated, "ok, we are inverted...and now we gotta get it." Over the next minute, completely inverted and still diving at a –9° pitch, the crew struggled to roll the plane, with the captain calling to "push push push...push the blue side [of the attitude indicator] up," "ok now let's kick rudder...left rudder left rudder," to which the copilot responded, "I can't reach it." The captain then replied, "ok right rudder...right rudder," followed 18 seconds later by: "gotta get it over again...at least upside down we're flying."

Despite the attempt to fly the plane inverted, which almost entirely arrested its descent, the aircraft had lost too much altitude in the dive, and was far beyond recovery. A few seconds before 16:21 (00:21 UTC), Flight 261 hit the Pacific Ocean at high speed between the coastal city of Port Hueneme, California, and Anacapa Island. At this time, pilots from aircraft flying in the vicinity reported in, with one pilot saying, "and he's just hit the water." Another reported, "Ah, yes sir, he, ah, he, ah, hit the water. He's, ah, down." The aircraft was destroyed by the impact forces, and all occupants were killed by blunt-force impact trauma.