What happened
On 3 November 2019, an Avianca Boeing 787-8, registration N796AV, was performing a scheduled international flight from Bogotá to Barcelona. While descending through flight level 260, the aircraft's speed increased rapidly, approaching its maximum permissible operating speed (VMO) of 360 kt.
During this phase of flight, the commander, acting as the pilot at the controls (PF), began making a passenger announcement via the PA system. As the aircraft' and speed increased, the relief pilot issued a "SPEED" callout. In response, the commander interrupted the announcement, extended the speed brakes, disengaged the autopilot, and applied significant input to the control column to pull the aircraft's nose up. This maneuver caused the vertical acceleration to fluctuate sharply between +2.14 g and +0.69 g. The sudden change in forces caused serious injuries to one passenger and one member of the cabin crew.
The investigation
The CIAIAC examined flight data recorder parameters, which showed that the aircraft's vertical descent profile had changed from VNAV SPD to VNAV PTH mode, causing the speed to accelerate toward the limit. The investigation analyzed the crew's task distribution and the commander's decision to perform non-essential tasks while flying the aircraft. Investigators also reviewed the aircraft's automation logic and the manufacturer's ability to replicate the speed increase.
Findings
- The Boeing 787-8 reached a maximum speed of 356.87 kt, just below the VMO.
- The commander's decision to make a passenger announcement without delegating flight path responsibilities to the pilot monitoring (PM) acted as a distraction.
- The pilot monitoring failed to detect the increasing airspeed.
- The abrupt change in vertical acceleration caused by the pilot's manual correction to prevent an overspeed was the primary cause of the injuries.
- The operator's internal investigation noted a lack of specific guidelines regarding passenger announcements during critical flight phases.