What happened
On November 3, 2021, at approximately 00:40 UTC, a Boeing 787-9, registration N36962, operated by United Airlines, encountered a technical malfunction during a commercial flight. The aircraft was in the cruise phase of flight at flight level 360, traveling from Ministro Pistarini International Airport toward Houston International Airport. While flying over the vicinity of Baradero, Buenos Aires, the crew identified a failure within the aircraft's pressurization system.
In response to the malfunction, the flight crew initiated an emergency descent to flight level 150. This lower altitude was selected to ensure the maintenance of cabin pressure and the safety of the 159 occupants on board. The aircraft subsequently diverted from its original flight path and returned to its point of origin, performing a landing at the departure airport without further incident or injuries to the 12 crew members and 147 passengers.
The investigation
The Argentine Transportation Safety Board (JST) conducted a technical review of the event. The investigation focused on the nature of the system failure and the subsequent operational decisions made by the crew. Following an analysis of the circumstances surrounding the incident and the condition of the aircraft after the event, the JST determined that the occurrence did not present significant lessons for the improvement of national operational safety. Consequently, the authorities decided to conclude the investigation and archive the proceedings.