Air India Phuket-Delhi flight incident: Pilot tested non-negative for psychoactive substance after hydraulic failure injured 24

The Aircraft Accident Investigation Bureau (AAIB) preliminary investigation into the August 4 Air India Phuket-Delhi incident found that the Airbus A320 briefly lost pressure in all three hydraulic systems while flying at 36,000 feet, leading to an autopilot disconnect, a stall warning and an altitude deviation that injured 24 people. The pilot-in-command was later found non-negative for a psychoactive substance in a confirmatory blood test, and investigators recommended that the Directorate General of Civil Aviation take action.

The finding is part of the preliminary investigation into Air India flight AI2379, an Airbus A320-251N carrying 145 people. "The confirmation of use of psycho-active substance is a serious concern," the bureau said, recommending that the DGCA take "appropriate actions" on priority to prevent abuse of psychoactive substances. The finding came from Air India flight AI2379, an Airbus A320-251N carrying 145 people.

The aircraft's flight-control system detected a loss of the green hydraulic system at 04:02:43 UTC, followed four seconds later by losses of the blue and yellow systems. The autopilot disengaged a second later and a continuous repetitive chime sounded, followed by a stall warning that lasted two seconds.


The co-pilot, who was flying the aircraft, initially responded before the pilot-in-command took control. The aircraft climbed 372 feet above its assigned altitude and then fell 292 feet. The blue hydraulic system recovered first, followed within seconds by the yellow and green systems, after which the flight controls returned to normal.

The seat-belt signs were off during the incident. Twenty passengers and four cabin crew members received medical assistance after the aircraft landed in Delhi. Twenty were discharged after treatment for minor injuries, while four with serious injuries were hospitalised. The aircraft sustained damage to cabin components including overhead bins, ceiling panels and handrails.

Both pilots passed their post-flight breath-analyser tests. The pilot-in-command's psychoactive-substance screening test was non-negative, as was the confirmatory blood test. The co-pilot tested negative in both tests.

The aircraft had been dispatched from Phuket with a Minimum Equipment List item related to its Power Transfer Unit, which had been invoked on July 28. The investigation has not established whether the PTU issue was connected to the hydraulic failure.

The crew chose to continue to Delhi rather than divert to the nearest en-route airport and later requested medical priority from air traffic control. The aircraft landed safely at Indira Gandhi International Airport at 05:30 UTC.

Air India said it was cooperating with the investigation, including by providing access to relevant "operational, maintenance and technical records". The airline also said it had started voluntary testing of 100% of its pilots following the incident and maintains "zero tolerance" for any breach of safety, fitness or regulatory requirements.

The AAIB has recovered the aircraft's flight-data and cockpit-voice recorders and downloaded their data for further analysis. Hydraulic components and fluid samples were also collected for testing, while Airbus technical experts inspected the aircraft from Aug. 13 to Aug. 15.

The investigation has not established a link between the pilot's test result and the hydraulic failure, or determined the cause of the failure. The AAIB said work on the "technical and other aspects" was continuing and that a final report would be published later.