One of the pilots on an Airbus A320 carrying more than 100 passengers was found to have smoked marijuana before the plane plummeted 300 feet and injured many onboard.

Twenty passengers and four cabin crew suffered injuries during the August 4 plunge, before the pilots regained control over the Air India flight from Phuket to Delhi.

Both pilots have been removed from duty as the investigation continues, but the revelation that one pilot tested positive for marijuana.

Under current Indian regulations, airlines need to test at least 10% of their flight crews each year for drugs.

After the mid-air plunge, Air India has announced it will drug test all of its pilots.

The current investigation hasn’t found a link between the captain’s reported positive test and the sudden loss of altitude.

But cabin crew on the Airbus complained to Air India that the captain did appear impaired onboard.

One person told the Times of India: ‘He was often sitting on the floor of the flight deck and tried to smoke. Cabin crew had to help him back to his seat.

‘He was not in full control of himself. He was unable to walk properly after exiting the aircraft.’

Air India’s senior vice president for flight operations told pilots: ‘We nevertheless now feel it is important to go further.

‘Accordingly, we have decided to undertake a full screening of all group pilots for any substances or medications that are not permitted under prevailing regulations.’

Last year, an Air India flight crashed and killed 260 people. Earlier this month, it was revealed that investigators are leaning towards deliberate pilot action moments before the crash.

The bombshell theory, which has been rumoured about for months since the June 12 crash in Ahmedabad, is looking increasingly likely in India’s investigation, according to sources.

The experts have already ruled out a mechanical failure, and they have not discovered evidence of sabotage, Bloomberg reports, citing people close to the probe, who asked not to be named as the potentially explosive findings are not yet public.

It means pilot action remains the strongest line of enquiry in the crash, which left only one suvivor.

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