The captain of an Air India flight that experienced a sudden loss of altitude earlier this month has tested positive for cannabis in a confirmatory drug test, according to reports, adding a new dimension to an ongoing investigation into the incident.

Air India flight AI2379, operating from Phuket to New Delhi on August 4, experienced a sudden change in altitude of around 300 feet while cruising, leaving 24 passengers and crew members injured. The Airbus A320neo subsequently landed safely in Delhi.

Both pilots underwent mandatory psychoactive-substance screening following the incident. The captain's initial test produced a result requiring further laboratory confirmation, and the subsequent confirmatory test reportedly detected marijuana.

Investigators are examining the circumstances surrounding the altitude loss, including the captain's conduct and the flight crew's actions during the incident.

According to reports, cabin crew members filed a complaint with Air India raising concerns about the captain's behaviour and whether he appeared fully in control of himself. Both pilots have reportedly been removed from flying duties pending the investigation.

The Aircraft Accident Investigation Bureau is conducting a broader inquiry into the incident, examining flight-data records, maintenance information and interviews with the crew. Airbus and France's Bureau of Enquiry and Analysis for Civil Aviation Safety (BEA) are also assisting with the technical investigation.

The investigation is also looking at possible technical factors. Reports citing a post-flight maintenance document say the aircraft experienced multiple system warnings, including indications involving its hydraulic systems, flight controls and autopilot before or during the altitude event.

The findings mean that investigators have not established that the captain's drug-test result was responsible for the aircraft's sudden altitude change. The technical and human factors are being examined separately as authorities work to determine the cause.

In response to the incident, Air India has announced that it will expand substance-abuse screening to all of its pilots, going beyond India's existing regulatory requirement for random testing of at least 10% of flight crew annually for psychoactive substances.

The expanded testing program will include checks during training, after flights and at designated locations such as the airline's Gurugram academy and pilots' home bases. The measure will also cover pilots working for Air India's low-cost subsidiary, Air India Express.

The incident comes as Air India faces heightened scrutiny over flight safety and operational standards, making the investigation into the Phuket-Delhi flight particularly significant for the airline and Indian aviation authorities. (ILKHA)