Many will remember the movie “Flight” which was released in 2012. In that film, lead actor Denzel Washington was an airline pilot – addicted to alcohol and cocaine – who suddenly finds himself becoming a hero when his plane during a routine flight suffers a fiasco as he puts it into an irreversible dive. , which appears destined to crash the plane to the ground. On the other hand, the pilot managed, with an exceptional maneuver, to land the plane in a field, saving most of the passengers. Few probably know that this movie is loosely based on a real event, but unfortunately with a very different outcome: tragedy Alaska Airlines Flight 261.
Journey like many others
It is January 31, 2000, when A.J MD-83 Alaska Airlines takes off from Puerto Vallarta International Airport, Mexico bound for Seattle-Tacoma, with a stopover in San Francisco. Alaska Airlines is one of the largest and most important domestic airlines in the United States that mainly uses the McDonnell Douglas Series 80 models, among the most famous and best-selling aircraft in the world derived from the famous DC-9.
At the controls is the 53-year-old Cmdr Theodore “Ted” Thompsonwith over 17,000 flying hours behind him and comes from the United States Air Force as an assisted second officer William “Bill” Tansky57, who in his career has accumulated more than 8,000 flying hours, mostly on the MD-80.
On that day, Flight 261 was carrying, in addition to three other crew members, 83 passengers Of these, 47 are destined for Seattle. MD-83 in the colors Alaska Airlines departs Puerto Vallarta Licenciado Gustavo Díaz Ordaz Airport at 13:37 local time (21:37 UTC) and is expected to arrive in San Francisco at 15:49 (23:49 UTC). The ascent to the expected flight altitude, that is, the 310th level corresponding to 31,000 feet (or 9,400 metres), was at first carried out in a completely regular manner, but only 15 minutes after takeoff, at an altitude of 28,500 feet (8,600 metres), the commander and second noticed an anomaly: pruning affiliate Horizontal stabilizer (that is, the horizontal part of the tail of the aircraft in the form of the letter T) is out of order.
This part of the aircraft’s aerodynamic surfaces is essential to maintaining its stance in flight, in particular Check out the pitch: When the pilot operates the stick by pulling (or pushing) it, the elevators on the horizontal stabilizer are activated. the pruning, On the other hand, it is a position adjustment (always along the pitch axis) that can be set manually and which involves the operation of the entire elevator block, which moves slightly (up or down) thanks to the “spoilInside the drift. The pilots are getting involved pruning In order to better maintain a horizontal position without continuing to interfere with the stick.
The horizontal equalizer is not responding
On that January day, the two pilots noticed that operating both levers on the stick and the horizontal elevator trim wheel was getting no response. At this point the normal procedure of mechanical failure to the elevator, assuming manual control of the aircraft. The MD-83 was stuck “trimmed” down a bit, so with that position to hitTo balance the movement, Thompson has to turn the stick, pulling it slightly towards himself.
At 16.09 the plane suddenly entered A.A steep dive, which is retrieved with great difficulty by the two officers. The commander informs air traffic control of what has happened:The middle… Alaska-two sixty-one, we’re… uh… on a dive here” And “I lost control, vertical dive“.
Air traffic controller Los Angeles I can hardly believe it through the answer.”Alaska sixty-two, repeat sirAt that point the commander reported that,Yeah, we’re at twenty-six thousand feet, we were vertical… dive… no more dive… but… uh… we lost vertical control of our planeAdding that they regained control of the plane, but the second responds in the negative.
At 16.11 Los Angeles ATC (Air Traffic Control) requested the situation, and Thompson reported that they were flying at about 26,000 feet.”Almost settledAt this point, the pilots are in contact with Alaska Airlines Ground Assistance and Maintenance, to try to resolve the issue, but the ground crew seems unable to do anything, leaving everything in the hands of the officers and approving their maneuvers to try to recover horizontal stability and an emergency landing in Los Angeles.
At 16.14, while the two pilots are trying to find a landing procedure that will prevent the plane from returning, Cmdr Passenger warning for what happened. “Folks, we had a flight control problem up front, and we’re working it out… Ah that’s LA over there on the right, that’s where we plan to go. We’re pretty busy here, fixing this situation, I don’t expect major problems once we get two subsystems back online. But we’re heading to LAX and I expect to park there in about twenty to thirty minutes.The commander did not yet know this, but at that moment he was only six minutes away from the tragedy.
At 16.17.01, Thompson ordered the guards to lock everything inside the cabin and fasten everyone’s seat belts and only 8 seconds later he heard a dark noise coming from the tail (“the great explosionAs heard in the recordings). MD-83 He goes into a deep dive again. The pilots do their best to regain buoyancy, extend the slats, and open the air brakes. car horn repeatsto risefor 34 seconds to indicate a sudden loss of altitude.
At 16.19 hours 29 seconds, the leader orders more slices by saying “Qhis is s…Another 14 seconds later may day. At 16.19.54, the black box records the voice of Thompson’s cabin saying “Ok, we’re inverted…now we have to make it…31 seconds laterAre we flying? …we are flying…we are flying…tell him what to do…“.
On 16/20/49 we hear the noise of the compressors stopping, and immediately after the engines have stopped. Alaska Airlines Flight 261 impacts the Pacific Ocean 4.3 kilometers north of California Island anacapa at 16.20 and 57 seconds. The commander’s last words wereAh… here we goAll passengers are killed instantly.
result of the investigation committee
The wreckage of the MD-83 aircraft rested on the seabed at a height of about 80 m. Its recovery made it possible to find out the cause of this irreparable failure. afterThe investigation lasted three years The accident is mainly attributed to maintenance deficiencies From the airline in Oakland, California.
Nine days after the accident, the horizontal stabilizer was recovered to the dismay of NTSB technicians (National Transportation Safety Board) Note that the “headwork” nut on the lever assembly is not attached. As noted Metal “Spring”. wrapped around the “screw” resulting from wearing the same thing, usury Which practically led to the disappearance of the “screw” thread.
The investigation found that Alaska Airlines, without objection from the FAA (Federal Aviation Administration), I had had interval extended to control that part years before the accident. Originally it was set every 5,000 flying hours but in July 1988 the company no longer used an hour limit but a time limit, set every 26 months. Based on the airline’s utilization rate at the time, this equated to 6,400 flying hours between inspections. This interval was increased again in April 1996 to 30 months, equating to about 9,550 flying hours, but the manufacturer, which in the meantime had become Boeing, fixed it every 30 months or 7,200 flying hours, depending on which event occurred first. .
So what really happened? Consumption of thread from “Viton” which did not qualify According to the schedule, he set a lock From the horizontal BC is in a position to oscillate under the aerodynamic efforts determined by the flight itself with the impossibility, due to wear, of being able to correct its position by the pilots (pruning). The stop nut was not designed to withstand such aerodynamic loads and thus broke nine minutes after takeoff, allowing the winch and its stabilizer to slip up and out of the nut causing a fatal dive. There was nothing Tansky and Thompson could do to take control of the plane.
Following the outcome of the commission of inquiry, the FAA issued a emergency guidance To all operators of 80 Series MDs to check their cranes and report any findings, thus discovering that two other aircraft had the same problem as Flight 261, both from Alaska Airlines.
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