Pilot seat movement at center of LATAM 787-9 dive investigation

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The focus of the investigation into an inflight upset aboard a LATAM Boeing 787-9 on March 11 has centered on the movement of a flight deck seat, two people briefed on the incident tell The Air Current.

The 787-9 was transiting between Sydney and Auckland, part of its regular one-stop service to Santiago, Chile when it experienced a steep nose down movement that injured at least 50 of the 263 people aboard.

What caused the seat to move is the key question for air safety investigators. One senior airline safety official briefed on the early facts said that based on the available information it was understood that the seat movement was “pilot induced, not intentionally.” Another person familiar with the investigation said “the seat movement caused the nose down” attitude of the aircraft and added that the possibility of an electrical short was also under review. The sequence of events between the seat movement and the steep dive experienced by the aircraft wasn’t yet known.

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Passengers onboard the aircraft reportedly said the captain told them the aircraft gauges “blanked out” during the upset, though those briefed said that was not the main focus of any inquiry.

Boeing referred any questions regarding the investigation to the Chilean DGAC, which did not immediately respond to a request for comment. Investigators in New Zealand say they have the jet’s black box in their possession.

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All Boeing commercial airplanes have a large yoke or control wheel that is positioned directly in front of the right and left pilot seats and each sits between legs of the flight crew while their feet are on the rudder pedals. 

Each seat can be moved in two different ways. One is through a switch on the side of the seat that can be manipulated to move the seat along a track while a pilot is seated. A second set of controls on the back of the seat below the headrest are typically used to move the seat for pilots to gain access when the seat is in a flight-ready position close to the controls. Those switches are covered and part of the backshell of the seat.

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Boeing was expected to issue a Multi-Operator Message (MOM) to 787 operators regarding the incident, though the specific topic of the MOM was not immediately known by The Air Current. 

While the precise details of the incident are not fully known, there is ample historical precedent for unintentional in-flight upsets or electrical issues. In 2014, a digital SLR camera became jammed between the left arm rest and the base of the side stick of a Royal Air Force A330 tanker causing a 4,400 foot loss in altitude and a maximum recorded descent rate of 15,000 feet per minute. The left seat was being moved “at the onset of the event,” according to investigators.In separate 2019 and 2020 incidents, drinks spilled on an A350 radio panel caused the shutdown of one of its Trent XWB engines prompting a redesign of part of the center pedestal that sits between the pilots.