Air India Flight to Delhi Briefly Lost All Three Hydraulic Systems at 36,000 Feet, Injuring 24

An Air India flight travelling from Phuket to Delhi experienced a rare and serious technical disruption at an altitude of 36,000 feet after all three of its hydraulic systems briefly lost pressure within a matter of seconds. The incident triggered an autopilot disconnect, a stall warning and a sudden change in altitude, leaving 24 people injured, according to a preliminary investigation. The incident involved Air India flight AI2379, operated by an Airbus A320neo. The aircraft was carrying 137 passengers, six cabin crew members and two pilots when the incident occurred on August 4.

According to the preliminary findings of India's Aircraft Accident Investigation Bureau (AAIB), the aircraft was cruising at Flight Level 360 when the green hydraulic system showed a loss of pressure at around 9:32 am IST. Approximately four seconds later, indications showed that pressure had also been lost in the blue and yellow hydraulic systems.

The simultaneous loss of all three hydraulic systems is considered unusual because the aircraft is designed with separate hydraulic circuits that provide redundancy for critical flight-control functions. The systems began recovering shortly after the failure, allowing the aircraft to regain normal hydraulic capability.

The disruption nevertheless caused the aircraft to experience what investigators described as an altitude upset. The autopilot disconnected and a brief stall warning was triggered as the aircraft moved away from its assigned altitude. The aircraft initially climbed several hundred feet above Flight Level 360 before descending below its assigned level.

The sudden movement caused injuries inside the cabin. Twenty passengers and four members of the cabin crew were injured, while parts of the aircraft's interior, including overhead compartments and ceiling fittings, were reportedly damaged. The incident occurred while the seatbelt signs were not illuminated, increasing the risk of passengers and crew being thrown around the cabin. The flight crew managed the situation and continued the journey toward Delhi after the aircraft's hydraulic systems recovered. The pilots informed air traffic control about the situation and requested priority medical assistance after landing. The aircraft eventually reached Delhi safely.

The AAIB has not yet determined why all three hydraulic systems appeared to lose pressure almost simultaneously. Investigators are examining the aircraft's components, maintenance records, flight-data recorder, cockpit voice recordings and other technical evidence to establish what caused the unusual sequence of events. Airbus and France's Bureau of Enquiry and Analysis for Civil Aviation Safety are also assisting in the investigation.

The preliminary report also highlighted a separate issue involving the pilot-in-command. A confirmatory test conducted after landing reportedly returned a non-negative result for a psychoactive substance, while the co-pilot's test was negative. However, the preliminary investigation has not established any connection between the test result and the hydraulic malfunction or the altitude upset.

The investigation remains ongoing, and the preliminary findings should not be treated as the final determination of the cause. Investigators are expected to examine whether the aircraft experienced a genuine simultaneous hydraulic failure or whether another technical issue, including an indication or component-related problem, contributed to the reported loss of hydraulic pressure.

The incident has drawn attention to the importance of multiple layers of redundancy in modern commercial aircraft. While the A320neo's hydraulic architecture is designed to maintain flight-control capability even when individual systems fail, the brief loss of all three systems presents an unusual technical question that investigators will need to resolve in their final report.

Disclaimer: This image is taken from daily excelsior.