New Delhi, Aug. 10 -- The Union civil aviation ministry, on Sunday, said that the Air Accident Investigation Bureau (AAIB) has begun its investigation into the Phuket- Delhi turbulence matter that occurred before landing in Delhi on August 4. "The occurrence has been classified as a serious incident and is under investigation by the Aircraft Accident Investigation Bureau (AAIB)," a statement from the ministry read. To be sure, the ministry had earlier said that the directorate general of civil aviation (DGCA) was investigating the matter. The government also said the psychoactive substance screening test of the pilot in command (PIC) showed a result requiring a confirmation test, a re-test. "As part of the Standard Operating Procedures following such an occurrence, both flight crew members underwent the prescribed psychoactive substance screening test. The screening test in respect of the PIC indicated a result requiring confirmatory testing. Samples have accordingly been sent to the designated laboratory for confirmatory analysis, and the final report is awaited," the statement read. The Air India aircraft, an A320 aircraft VT-EXO, operating flight AI 2379 from Phuket to Delhi, experienced a sudden loss of altitude of approximately 300 feet during cruise, after which the aircraft stabilised and subsequently landed safely at Delhi. During the occurrence, injuries were reported to a few passengers and cabin crew members on board. The aircraft was carrying 137 passengers and eight crew members. Civil aviation minister Ram Mohan Naidu, on Wednesday said two crew members who suffered spinal injuries continued to remain in Fortis hospital. "Pending investigation and completion of the prescribed process, both flight crew members have been taken off roster by the DGCA. Further action, as appropriate, will be taken based on the outcome of the investigation and confirmatory test results". Earlier, Air India spokesperson said, "...Air India undertakes regular drug testing of crew members in compliance with civil aviation regulations, independent of any specific flight or operational incident. We will continue to cooperate with the relevant authorities as required."...