An Air India Airbus A320neo flying from Phuket to Delhi on August 4 briefly lost pressure in all three hydraulic systems while cruising at 36,000 feet, triggering an autopilot disconnect, a stall warning and a rapid altitude upset that injured 24 people.
The Aircraft Accident Investigation Bureau (AAIB), in its preliminary report released on September 4, said the aircraft initially climbed 372 feet before dropping 292 feet below its assigned altitude. With seatbelt signs switched off, 20 passengers and four cabin crew members needed medical attention; four people were hospitalised with serious injuries. The aircraft later landed safely in Delhi.
The report also revealed that the pilot-in-command (PIC) tested “non-negative” for a psychoactive substance in both initial and confirmatory testing, while the co-pilot tested negative in both. AAIB called the substance finding a “serious concern” and recommended action by the Directorate General of Civil Aviation (DGCA).
Air India has since terminated the PIC’s employment and said it has begun voluntary testing of 100% of its pilots, while maintaining that safety remains its highest priority. The cause of the triple hydraulic-system pressure loss is still under investigation, with Airbus and France’s BEA assisting.
A Flight Turned Turbulent
AI2379, an Airbus A320-251N registered VT-EXO, was carrying 145 people 137 passengers, including three infants, six cabin crew and two pilots when the incident unfolded over the Kolkata Flight Information Region. According to the AAIB timeline, at 04:02:43 UTC, the aircraft detected a loss of pressure in its green hydraulic system.
Four seconds later, the blue and yellow systems also showed pressure loss. The autopilot disconnected almost immediately, followed by a continuous cockpit warning and a two-second stall warning. The hydraulic systems began recovering within seconds, restoring normal flight-control operation.
During this brief but critical sequence, the aircraft first climbed about 372 feet above FL360 before falling 292 feet below its assigned level. The co-pilot, who was the pilot flying, initially responded before the PIC took control. Because the seatbelt signs were off, passengers and crew were thrown around the cabin. The AAIB recorded damage to ceiling panels, overhead-bin doors, handrails and other interior fittings.
Twenty passengers and four cabin crew members received medical attention after landing, while four people with serious injuries were hospitalised. The crew chose to continue to Delhi rather than divert, later requesting medical priority from air traffic control before landing safely at Indira Gandhi International Airport.
What Investigators Are Examining
The unusual part of the incident is that the A320neo has three separate hydraulic systems green, blue and yellow designed to provide redundancy. The preliminary report confirms that all three showed a loss of pressure almost simultaneously, but it does not yet establish why.
The aircraft had also been operating under a Minimum Equipment List provision concerning its Power Transfer Unit (PTU), which had been deferred on July 28. Investigators have not concluded that this was responsible for the incident. No adverse weather was reported by the crew or air traffic control at the time of the upset.
AAIB has recovered and examined the flight-data and cockpit-voice recorders and is analysing maintenance and operational records, hydraulic components and fluid samples. Airbus experts and France’s Bureau of Enquiry and Analysis for Civil Aviation Safety (BEA) have assisted with the aircraft inspection.
Separately, both pilots underwent post-flight medical checks in Delhi. Their breathalyser tests were satisfactory, but the PIC’s psychoactive-substance screening was “non-negative”, followed by another “non-negative” result in confirmatory testing.
The co-pilot tested negative in both. AAIB described the confirmed finding involving one flight crew member as a “serious concern” and urged the DGCA to take appropriate action to prevent substance abuse in aviation. Air India subsequently said the PIC’s employment had been terminated with immediate effect under its zero-tolerance approach to safety, fitness and regulatory violations.
The airline also said it would continue cooperating with investigators and had started voluntary testing of all its pilots as an additional safety measure. Importantly, the preliminary report does not establish that the pilot’s test result caused or contributed to the hydraulic failure or altitude upset.
The Logical Indian’s Perspective
An aviation emergency lasting only a few seconds can have consequences that stay with passengers and crew long after an aircraft reaches the ground. The AI2379 incident is a reminder that aviation safety cannot depend on one layer of protection alone aircraft systems, maintenance, cockpit decisions, medical fitness, cabin procedures and regulatory oversight all have to work together.
At the same time, preliminary findings must be treated with care: the triple hydraulic failure still has no established cause, and the pilot’s non-negative test result should not be presented as an explanation for the technical malfunction unless investigators establish such a link.
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