AI Phuket-Delhi flight: AAIB flags hydraulic failure, pilot's drug test

An Air India Airbus A320 carrying 145 people suffered near-simultaneous loss of all three hydraulic systems while cruising at 36,000 feet on a Phuket-Delhi flight on August 4, triggering an autopilot disconnect, a brief stall warning and an altitude upset that injured 24 people, the Aircraft Accident Investigation Bureau(AAIB) said in a preliminary investigation that sought action against pilot-in-command for testing positive for banned drugs upon landing. The report did not establish that the pilot-in-command's drug abuse contributed to the hydraulic failure or the altitude upset. AAIB said its investigation into the technical and other aspects of the accident remains underway. With no adverse weather reported at the time, investigators are examining the aircraft's hydraulic-system failure and other factors.
AAIB said the aircraft had been flying at 36,000 feet with the seat-belt signs switched off when the event occurred, leaving passengers and cabin crew vulnerable to the sudden aircraft movement. The cabin supervisor informed the cockpit crew that passengers and crew members had been injured. The pilots assessed the situation and decided to continue to Delhi rather than divert to the nearest airport.The report said the flight took off from Phuket in Thailand at 7.11am IST and initially reported no abnormalities. At 9:10am, it entered the Kolkata Flight Information Region. The aircraft’s flight-control system detected a loss of the green hydraulic system at 09:32 am. Four seconds later, it detected the loss of the blue and yellow hydraulic systems.
The aircraft itself suffered damage largely confined to the cabin. Investigators documented cracked or deformed ceiling panels, dislodged passenger-service-unit panels, broken handrails, detached overhead-bin doors, a broken emergency-exit handle and a lavatory commode uprooted from its original position. 
The preliminary report separately details the results of post-flight medical testing. Both pilots underwent breathalyser examinations after arriving in Delhi, with satisfactory results. They were also tested for psychoactive substances. The co-pilot’s sample was negative. The pilot-in-command’s initial sample was non-negative, and a blood sample was subsequently sent to a pathological laboratory for confirmation. That confirmatory result was also reported as non-negative. 
AAIB has not stated what substance was detected or whether it had any operational effect on the flight. “The confirmation of use of psycho-active substance is a serious concern and AAIB recommends appropriate actions by DGCA on priority,” the bureau said. In its interim safety recommendation, AAIB said: “In view of a non-negative result for psychoactive substances for one of the flight crew, it is recommended that DGCA may take appropriate actions as deemed fit to prevent abuse of psychoactive substances.” The AAIB recommended that the regulator, Directorate General of Civil Aviation (DGCA), take appropriate action as deemed fit to prevent abuse of psychoactive substances. The AAIB called their use a serious concern and said a detailed probe regarding technical and other aspects remains underway.
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. 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. “The airline maintains zero tolerance for any breach of safety, fitness or regulatory requirements and will take appropriate action wherever warranted.”