The pilot-in-command (PIC) of the August 4 Phuket-Delhi Air India flight , which suffered a sudden loss of altitude during cruise and left 20 passengers and four crew members injured, tested “non-negative” for a psychoactive substance in a confirmatory test, a preliminary Aircraft Accident Investigation Bureau (AAIB) report released on Friday said. The Airbus A320neo with 137 passengers suffered an “altitude upset” after losing all three hydraulic systems within seconds while cruising at 36,000 feet, the agency found.
It added that it started voluntary testing of 100% of its pilots as a further step to reinforce its safety-first approach following the incident.
In a statement, Air India cited the preliminary report and said the airline will continue to extend full cooperation to the investigation, including access to operational, maintenance and technical records. “The airline maintains zero tolerance for any breach of safety, fitness or regulatory requirements and will take appropriate action wherever warranted.”
At 4.02am, the autopilot disengaged, and a continuous repetitive chime sounded. Initially, it gained 372 ft and fell by 292 ft from its assigned FL360 during the event,” said the AAIB report. It added that the blue hydraulic system was recovered around 09:32am.
It did not establish any link between the psychoactive substance finding and the altitude upset. “Detailed investigation regarding technical and other aspects is underway. Three seconds later, the stall warning was triggered for two seconds. “…the aircraft encountered altitude upset. A few seconds later, the yellow and green hydraulic systems were recovered, leading to the recovery of the control surfaces and allowing the aircraft to return to normal operating condition. It recorded warnings of low pressure in the green hydraulic system followed by the blue and yellow systems, the autopilot switching off and faults involving the left and right elevators. The report recorded low-level warnings for the yellow and blue hydraulic reservoirs. AAIB collected maintenance and operational records and relevant information from Delhi and Kolkata ATC.
The report said the PIC was the pilot monitoring, or crew member in a two-pilot aircraft not actively handling the primary controls, and the copilot tested negative in both tests. The AAIB said aircraft maintenance personnel generated the Post Flight Report, which was examined to check the in-flight warning and failure messages. The report said the investigation team inspected the aircraft, collected hydraulic components and fluid samples, and obtained fuel and oil samples for examination.
