Key Takeaways

• Three hydraulic systems failed simultaneously on VT-EXO, causing an altitude upset and cabin damage.
• Pilot-in-command tested positive for psychoactive substances, prompting AAIB recommendations for DGCA action.
• Aircraft landed safely in Delhi with 24 people requiring medical attention after the incident.
• The plane was dispatched with an active Minimum Equipment List item for its Power Transfer Unit.

The preliminary investigation into the August 4 Air India Phuket-Delhi accident has illuminated a critical series of technical and human factors that converged during a routine cruise. The Aircraft Accident Investigation Bureau (AAIB) report indicates that the aircraft’s three hydraulic systems-green, blue, and yellow-lost pressure within seconds while cruising at 36,000 feet. This technical anomaly triggered an autopilot disengagement, stall warnings, and a significant altitude upset. Simultaneously, the report highlighted a severe safety concern regarding the Pilot-in-Command, who tested positive for psychoactive substance use following the flight.

The immediate technical breakdown unfolded with alarming speed. At 04:02:43 UTC, the flight control system detected a loss in the green hydraulic system. Just four seconds later, the blue and yellow systems also failed. This simultaneous loss of all three hydraulic pressures caused the autopilot to disengage and activated a continuous repetitive chime. The aircraft experienced an altitude upset, gaining 372 feet before falling 292 feet from its assigned flight level. The sudden movement threw passengers and crew around the cabin, resulting in extensive damage including cracked ceiling panels, dislodged overhead bins, and a broken emergency exit handle. Despite the injuries sustained, including four hospitalizations, the flight crew maintained control and landed safely in Delhi approximately ninety minutes after the initial failure.

Central to the inquiry is the condition of the aircraft's hydraulic infrastructure and its operational status prior to departure. Investigators have flagged that the aircraft, identified as VT-EXO flight, was dispatched from Phuket under an active Minimum Equipment List item for the Power Transfer Unit. The PTU serves as an auxiliary hydraulic source shared between the green and yellow systems. Its status at the time of the failure is a primary focus of the ongoing probe, as the unit is designed to automatically operate if there is a pressure delta of 500 psi between the systems. The report clarifies that hydraulic fluid cannot be transferred between systems, and each system maintains its own reservoir, making the simultaneous failure of all three lines particularly anomalous and significant for technical analysis.

The human element of the incident has drawn equally intense scrutiny from regulatory bodies. Post-flight testing revealed a stark contrast between the two pilots. Both underwent breath analyser tests which returned satisfactory results. However, subsequent psychoactive substance detection tests returned a non-negative result for the Pilot-in-Command, a finding confirmed by a follow-up laboratory blood test. The co-pilot tested negative on both counts. The AAIB has explicitly recommended that the Directorate General of Civil Aviation (DGCA) take appropriate action against the Pilot-in-Command. The interim safety recommendation emphasized that the confirmation of psychoactive substance use is a serious concern and urged the regulator to act on priority to prevent such abuse.

The physical aftermath of the incident underscores the severity of the hydraulic loss. With seatbelt signs off during cruise, the sudden upset caused injuries to 24 people, including four cabin crew members. The cabin damage was extensive, featuring a lavatory commode uprooted from its original location and a bent crew seat. The aircraft, an eight-year-old A320neo carrying 145 people, entered the Kolkata Flight Information Region just before the incident. The flight control system's ability to recover the blue system first, followed by the yellow and green systems within seconds, allowed for a swift recovery of normal flight control surfaces. However, the damage to the cabin and the injuries sustained highlighted the violent nature of the altitude upset despite the technical recovery of the flight controls.

The role of the Power Transfer Unit (PTU) in this sequence of events remains a critical point of analysis. The PTU acts as an auxiliary pressure supply for the green or yellow systems without transferring fluid between them. It operates automatically based on pressure differentials. The fact that the aircraft was dispatched with an active Minimum Equipment List item for this component suggests that the auxiliary support mechanism was not fully operational or monitored in the standard manner prior to the flight. Investigators have downloaded flight recorder data, which is currently under analysis. A technical team from Airbus and France's BEA inspected the aircraft in Delhi in mid-August, removing hydraulic components and fluid samples for further testing to determine the root cause of the simultaneous pressure loss.

Air India A320neo Hydraulic Failure: Future Regulatory Impacts

The findings from this incident point toward stringent regulatory changes in both medical screening and equipment dispatch protocols. The confirmation of psychoactive substance use by the Pilot-in-Command is likely to force the DGCA to tighten pre-flight testing procedures, potentially moving beyond breath analysers to include more comprehensive blood or saliva testing for a wider range of substances. Furthermore, the operational context of the Air India A320neo hydraulic failure, particularly the reliance on a decommissioned Power Transfer Unit, will likely lead to stricter interpretations of Minimum Equipment Lists. Airlines may face new guidelines requiring higher levels of redundancy or immediate rectification of such items before dispatch, ensuring that auxiliary systems critical for hydraulic balance are fully functional to prevent catastrophic simultaneous failures.