India, Aug. 10 -- The civil aviation ministry on Sunday said the Air Accident Investigation Bureau (AAIB) has begun investigating the turbulence-related incident involving an Air India flight from Phuket to Delhi on August 4.

"The occurrence has been classified as a serious incident and is under investigation by the Aircraft Accident Investigation Bureau (AAIB)," the ministry said in a statement. The ministry had earlier said the Directorate General of Civil Aviation (DGCA) was investigating the matter.

The government also said a psychoactive substance screening test of the pilot in command (PIC) returned a result requiring confirmatory testing. "As part of the Standard Operating Procedures , both flight crew members underwent the presc...