Air India has dismissed the pilot-in-command of its Phuket-Delhi flight AI2379 after he tested positive for a psychoactive substance following a serious mid-air incident that left several passengers injured.

The Tata Group-owned airline said the captain's services were terminated with immediate effect, stressing that violations related to flight safety, medical fitness or regulatory requirements would not be tolerated.

The incident took place on August 4 when the Airbus A320, carrying 145 people, was cruising at an altitude of 36,000 feet over Odisha.

A preliminary investigation by the Aircraft Accident Investigation Bureau (AAIB) found that the aircraft experienced a near-simultaneous failure of all three hydraulic systems. The technical malfunction led to the autopilot disconnecting and briefly triggered a stall warning.

During the incident, the aircraft first climbed by around 372 feet before dropping approximately 292 feet from its assigned flight level. A total of 24 passengers were injured during the sudden altitude fluctuations.

The AAIB report said the co-pilot was operating the aircraft when the emergency unfolded and attempted to stabilise the situation. The pilot-in-command subsequently took control, after which the aircraft experienced what investigators described as an altitude upset.

The flight controls eventually recovered, and the aircraft resumed normal operations before landing safely in Delhi.

Following the landing, both pilots underwent mandatory testing for psychoactive substances. While the co-pilot tested negative, the captain returned a positive result in a confirmatory test.

However, the AAIB's preliminary findings did not establish a link between the pilot's positive test result and the technical failure or the aircraft's sudden loss of altitude.

The aviation investigation agency nevertheless described the confirmed use of psychoactive substances by the pilot as a serious concern and recommended that the Directorate General of Civil Aviation (DGCA) take appropriate action.

The AAIB also noted that the aircraft had undergone a pre-flight inspection by maintenance personnel and no technical irregularities had been recorded before departure. A detailed investigation into the hydraulic failure and other aspects of the incident is continuing.

Initially, the crew had reported encountering turbulence after landing in Delhi. However, once AAIB investigators arrived at the airport and began collecting evidence, the occurrence was formally classified as an accident.

Responding to the preliminary investigation report, Air India said it was fully cooperating with authorities and had provided access to operational, maintenance and technical records.

The airline reiterated that safety remained its top priority and said its pilots are subject to regular training, proficiency assessments, medical examinations and regulatory checks.

As an additional safety measure following the incident, Air India said it has begun voluntarily testing all of its pilots for psychoactive substances.