The Ministry of Civil Aviation has asked the Directorate General of Civil Aviation to examine how psychoactive-substance testing is handled in other countries and assess whether India's existing framework needs to be strengthened or changed, according to ministry sources cited by Indian media.

Both pilots underwent the prescribed psychoactive-substance screening following the incident, according to the Aircraft Accident Investigation Bureau.

The Civil Aviation Ministry said the pilot-in-command's initial screening produced a result requiring confirmatory analysis, after which the sample was sent to a designated laboratory. Media reports later said the confirmatory test was positive for marijuana.

The DGCA removed both pilots from the flying roster pending completion of the investigation and testing process.

Under the existing DGCA framework, aviation personnel who test positive for psychoactive substances are referred to a rehabilitation programme. A second positive result can lead to a three-year suspension of the person's licence, while a third violation can result in cancellation.

Civil Aviation Minister K Rammohan Naidu has said the government is taking the issue seriously and would consider changes if the current regulations are found to be inadequate.

Any decision on changing the framework is expected after the DGCA completes its examination of international practices.

Investigators are separately assessing a series of technical warnings recorded after the flight.

A purported post-flight maintenance report for the Airbus A320, registered VT-EXO, listed repeated low-pressure warnings involving the aircraft's green, blue and yellow hydraulic systems, together with low fluid-level indications in the yellow and blue reservoirs.

The report also recorded two autopilot disconnections, left and right elevator flight-control faults and other messages involving engine anti-ice systems and the aircraft's emergency exit doors.

Failure messages also flagged the hydraulic system, an elevator computer and a high-pressure indication linked to the nose landing gear door and engine anti-ice valve system.

The maintenance report does not establish whether any of those warnings caused or contributed to the aircraft's sudden loss of altitude, and investigators are continuing to examine the sequence of events, system data and crew actions.

The AAIB is investigating the incident with technical assistance from Airbus and France's Bureau of Enquiry and Analysis for Civil Aviation Safety.

The investigation covers technical, operational, medical and human-factor evidence, including aircraft systems, flight data, maintenance and operational records, medical information and interviews.

Air India initially described the incident as turbulence and has said it is cooperating with the authorities.

The AAIB has cautioned against drawing conclusions from any single piece of information while the investigation remains underway. Preliminary findings are expected within the timeframe required under the applicable rules and International Civil Aviation Organization protocols.

- With inputs from agencies.