The Air India Phuket-Delhi flight has now undergone a serious turn after the Aircraft Accident Investigation Bureau (AAIB) conducted a preliminary investigation and found that all the three hydraulic systems in the Airbus A320 lost pressure temporarily at the same time at 36,000 feet that the flight was cruising. (Glitch in water, on 4 th August, it was earlier reported that the flight was hit by threatening turbulence which injured 24 persons and caused extensive damage inside the aircraft cabin).
The AAIB preliminary report has also raised suspicion of something else regarding the pilot-in-command (PIC), which is that the pilot apparently returned a “non-negative” result following a post-flight test for a psychoactive substance. The airline regulator is said to be contemplating additional measures.
Air India Phuket-Delhi Flight Faced Triple Hydraulic Failure
Air India flight AI 2379, bound for New Delhi from Phuket, was at FL 360 when the aircraft suddenly suffered a mechanical fault.
As per the AAIB report, the low pressure in the green hydraulic system was detected first. About 4 seconds later the blue and yellow hydraulic systems also lost pressure.
Total power loss of all three hydraulic systems is notable since at the time the helicopter was displaying a number of flight-control functions: A failure for the autopilot to engage and a sounding alarm in the cockpit and stall warning, sounded briefly.
The aircraft climbed to 372 feet above its Assigned Cruising Altitude, then descended to 292 feet below A.C.A. Hydraulic pressure was restored within seconds and the Flying-Control Surfaces responded normally.
24 People Injured During Mid-Air Incident
The unexpected altitude upset reportedly took place when the seat-belt signs had been turned off the aircraft. Much of the cabin provided a ride for its occupants and crew.
Of the 24 who were injured, 20 passengers and four cabin crew. It was reported that the injuries sustained by the bulk of those affected were minor injuries, although four individuals suffered more serious injuries necessitating hospital treatment.
The aircraft sustained damage to a number of interior fittings including overhead panels, PSUs, handrails and overhead-bin doors.
However the hydraulic systems recovered on the aircraft and the crew continued to Delhi rather than divert.
Pilot Drug Test Raises Additional Safety Questions
The AAIB preliminary report on Air India Phuket flight sheds light on several key points. One of the most important is related to the pilot-in-command.
Both pilots did all the post-flight tests. Both pilots had negative results to alcohol breath-tests. The initial screening for psychoactive-substance was ‘non-negative’ for the PIC.
Later confirmatory blood test also showed a positive result for the PIC while the co-pilot showed a negative. The AAIB reported that the confirmation of the usage of psychoactive substance was a matter of serious concern and requested the DGCA to take suitable action.
Note that the initial investigation has not yet proven that the pilot’s test result was the cause of the hydraulic failure. Technical and human factors are separately under investigation.
Aircraft Was Operating Under MEL Conditions
The investigation has also been looking into the maintenance history of the aircraft.
The Airbus A320 was operated with an MEL condition on the Power Transfer Unit (PTU). AFTMEAJS the PTU is a part of the aircraft hydaulic systems.
Nevertheless, the AAIB has not concluded that the PTU condition led to the triple hydraulic failure. The concerned hydraulic parts are being stripped down for investigation, and servicing records and technical information are being studied.
Airbus and BEA Assist in Investigation
The inquiry is still in progress and being supported by Airbus and Bureare of Enquiry and Analysis for Civil Aviation Safety (BEA) of France.
The AAIB is looking at the FDR, CVR, maintenance records, various hydraulic components, fluid samples and ATC data to find out why all three hydraulic systems failed within seconds of each other.
The agency has emphasized that the results were preliminary and that no probable cause has been determined.
Air India Begins Pilot Drug Testing
Subsequent to the AAIB results, Air India introduced voluntary drug testing of pilots. This is an indication of increased emphasis on crew health and aviation safety.
This announcement is happening while the airline is under closer examination with regards to its operating and safety standards. The Phuket-Delhi incident may have larger bearings for pilot testing, aircraft maintenance and oversight procedures across the airline industry in India.
The incident also brings to light for passengers how a combination of technical systems and human factors may converge during the course of a flight. The final AAIB report should offer more insight into the chronological order of events as well as whether maintenance, operational or procedural issues played a role.
