India, Aug. 13 -- Air India and Air India Express will carry out psychoactive substance testing for all their pilots against the backdrop of the pilot-in-command of the Phuket-Delhi flight that suddenly lost 300 feet in altitude last week testing positive, according to sources.

Together, there are more than 5,000 pilots at the two airlines that are owned by the Tata Group.

In an internal message sent out to the pilots, both airlines said it has been decided to undertake a full screening for any substances or medications that are not permitted under prevailing regulations.

This testing is mandatory and will start on Thursday, the sources said.

The testing will be conducted concurrently with training at the Gurugram Academy, post-flight...