Air India pilot tested non negative for psychoactive substance, AAIB says

An Air India pilot-in-command tested non-negative for a psychoactive substance after a Phuket to Delhi flight suffered a temporary loss of all three hydraulic systems and an altitude upset that injured 24 people, according to a preliminary report by India’s aviation accident investigator.

The Aircraft Accident Investigation Bureau (AAIB) said the confirmatory blood test of the pilot-in-command was non-negative, while the co-pilot tested negative. It described the confirmed use of a psychoactive substance as a “serious concern” and recommended that the Directorate General of Civil Aviation take appropriate action on priority.

The report does not establish that the test finding was connected to the events aboard the aircraft. The AAIB said its investigation into the technical and other aspects of the 4 August accident remains underway and that a final report will be issued in due course.

Air India Flight AI 2379 was operating from Phuket to Delhi with 145 people aboard, including 137 passengers, six cabin crew and two pilots. The Airbus A320-251N, registered VT-EXO, entered the Kolkata Flight Information Region and was instructed by air traffic control to climb from 34,000 feet to 36,000 feet.

At 04:02:43 UTC, while cruising at 36,000 feet, the aircraft’s flight-control system detected a loss of the green hydraulic system. Four seconds later, it detected the loss of the blue and yellow hydraulic systems.

The autopilot disengaged a second later and a continuous repetitive chime sounded. At 04:02:51 UTC, a stall warning was triggered for two seconds.

The co-pilot, who was flying the aircraft at the time, responded before the pilot-in-command took over the controls.

The aircraft then experienced what the AAIB described as an “altitude upset.” It initially climbed 372 feet above its assigned flight level and subsequently descended to 292 feet below it.

The blue hydraulic system recovered at about 04:02:52 UTC, followed within a few seconds by the yellow and green systems. The flight-control surfaces recovered and the aircraft returned to normal operating condition, the report said.

The seatbelt signs were off at the time. Some passengers and cabin crew were injured during the event, and the cabin supervisor informed the pilots.

After assessing the situation, the flight crew decided to continue to Delhi rather than divert to a nearer airport. They later sought medical priority from Delhi air traffic control.

The aircraft landed safely at Delhi at 05:30 UTC and taxied to its parking bay under its own power.

Medical assistance was provided to 24 people after landing, including 20 passengers and four cabin crew members. Twenty were discharged after treatment for minor injuries, while four people with serious injuries were hospitalized.

The aircraft also sustained damage inside the cabin, including to overhead stowage bins and ceiling panels. The AAIB classified the occurrence as an accident after assessing the injuries and other evidence collected following the flight.

Pilot undergoes confirmatory test

Both pilots underwent post-flight breath-analyzer examinations because the flight originated outside India. The AAIB said the results for both crew members were satisfactory.

They were also tested for psychoactive substances. The pilot-in-command returned a non-negative result in the initial screening, prompting investigators to send blood samples from both pilots to a laboratory for confirmatory testing.

The pilot-in-command again tested non-negative, while the co-pilot tested negative in both tests. The preliminary report does not identify the psychoactive substance.

In an interim safety recommendation, the AAIB said the DGCA should take “appropriate actions as deemed fit to prevent abuse of psycho-active substance.”

“The confirmation of use of psycho-active substance is a serious concern,” the bureau said, recommending action by the regulator “on priority.”

Investigators examine hydraulic systems

The preliminary report also provides details of the aircraft’s hydraulic systems and maintenance status.

Before departure from Phuket, maintenance personnel carried out a pre-flight inspection and recorded no discrepancies apart from an already invoked Minimum Equipment List item relating to the aircraft’s Power Transfer Unit, or PTU. The MEL item had been invoked on 28 July.

The report does not attribute the hydraulic event to the PTU or the deferred MEL item.

The A320 has three hydraulic systems: green, blue and yellow. They supply hydraulic power to various aircraft systems and have separate reservoirs. The PTU provides an auxiliary source of pressure for the green and yellow systems without transferring hydraulic fluid between them.

Investigators removed relevant hydraulic components from the aircraft for further analysis. The flight-data recorder and cockpit-voice recorder were also recovered and their downloaded data is being examined.

Technical experts assigned by France’s BEA, the investigating authority representing the aircraft’s state of design and manufacture, inspected the aircraft between 13 and 15 August. Hydraulic components and samples were subsequently collected for testing.

The AAIB has also collected maintenance and operational records from Air India, as well as fuel and oil samples and information from air traffic control in Delhi and Kolkata.

The report said no adverse weather was reported by either the flight crew or air traffic control during the altitude upset.

The bureau said records and data collected from the various parties are still being scrutinized and that its detailed investigation is continuing.