Key Takeaways

• Air India flight AI 2379 suffered hydraulic issues, contradicting initial turbulence reports.
• 17 passengers injured during 300-foot altitude drop on Airbus A320 neo.
• Nine fault messages recorded in one minute before pilot manual intervention.
• Aircraft continued to Delhi for medical and engineering support after incident.
• AAIB investigating serious incident; Airbus assessment requested but response pending.

The Phuket-Delhi flight that experienced a “momentary loss in altitude” on August 4, injuring 17 people on board, was preceded by a cascade of failures involving the aircraft’s hydraulic and flight-control systems, according to multiple sources familiar with the matter, contradicting the airline’s initial attribution of the incident to turbulence.

Nearly 2.5 hours after taking off from Phuket at 6.56 a.m., Air India flight AI 2379 operated on Airbus A320 neo was hit by a cascade of technical failures at 9.32 a.m. IST, involving the aircraft’s hydraulic and flight-control systems. The sequence involved low-pressure indications and failures affecting one or two hydraulic systems at a time, with different combinations involving all three systems - an occurrence several pilots described as extremely rare.

This was followed by an autopilot disconnect and simultaneous fault indications affecting both the left and right elevators, which are the control surfaces that move the aircraft’s nose up or down. The A320 neo has three independent hydraulic systems that power critical functions including the primary flight controls, landing gear, nose-wheel steering, thrust reversers, flaps and slats, and braking systems.

The automated post-flight maintenance report records failures and warning indications in different hydraulic systems, occurring either individually or in combinations of two systems but affecting all three of them, according to a source who has seen a copy of the report. The report records nine such fault messages within one minute.

As the aircraft pitched up and a stall warning (indicating loss of lift or height) was triggered, one of the pilots took manual control and attempted to push the nose down, according to another Air India source familiar with the sequence of events. The pilot may have applied significant control input while attempting to recover the aircraft, the source said, causing the aircraft to lose around 300 feet of altitude in a matter of moments and throwing passengers and crew upward.

The available technical records do not show further fault messages after this sequence. Sources said this indicates that the flight-control systems were recovered following the pilots’ intervention, although the precise relationship between the technical failures, the flight-control response and the subsequent altitude excursion remains subject to investigation.

The pilots decided to continue to Delhi rather than divert to a nearby airport due to the availability of better medical facilities for the injured passengers as well as aircraft engineering support.

The incident has been classified as a serious incident and is being investigated by the Aircraft Accident Investigation Bureau (AAIB). Neither Air India nor the Ministry of Civil Aviation has mentioned the technical fault indications in their respective press statements.

Air India’s initial statement attributed the momentary loss of altitude to “in-flight turbulence”, but subsequent statements did not repeat the reference to turbulence. The Ministry’s statement, too, made no mention of turbulence. Neither Air India nor the Ministry statement mentioned any snags encountered during the flight.

Air India has also sought a technical assessment from Airbus and is awaiting the manufacturer’s response to a questionnaire relating to the incident, according to sources familiar with the matter. The nature of the technical issues referred to Airbus could not be independently established.

Technical Anomalies and Operational Response

The revelation that the incident was caused by a hydraulic system failure rather than atmospheric turbulence marks a significant shift in the understanding of the August 4 event. For the Airbus A320 neo, a wide-body twin-engine jet airliner, hydraulic systems are the lifeline of flight control. The plane relies on three independent systems to operate essential components. When these systems begin to fail simultaneously or in complex combinations, it creates a scenario that aviation experts consider exceptionally rare and dangerous.

The automated maintenance report provides a chilling timeline of the technical degradation. Nine distinct fault messages appearing within a single minute suggest a rapid cascade effect rather than a gradual wear-and-tear issue. This rapid succession likely overwhelmed the onboard diagnostics and the pilots' ability to rely on automated safety nets, forcing the transition to manual control.

When the autopilot disconnected and the elevators-critical for pitch control-showed simultaneous faults, the aircraft’s ability to maintain its flight path naturally was compromised. The pilot’s intervention, while necessary, resulted in a sharp descent of 300 feet. This physical shock to the cabin is what led to the injuries reported by 17 individuals on board. The decision to continue to Delhi was a calculated risk, prioritizing access to specialized medical care and on-ground engineering expertise over the immediate safety of a diversion, a decision that highlights the severity of the situation and the confidence the crew placed in the aircraft’s remaining capabilities after the initial recovery.

Air India Flight AI 2379 Awaits Manufacturer Verification

The ongoing investigation by the Aircraft Accident Investigation Bureau (AAIB) is critical in establishing the root cause of this rare event. While the immediate technical anomalies have been identified through the maintenance logs, the deeper engineering causes remain obscured until Airbus provides its assessment. The airline’s silence on the specific technical snags in its official statements suggests a cautious approach, likely to avoid prejudicing the investigation or causing unnecessary panic among passengers and the public.

The lack of mention regarding turbulence in subsequent statements by both Air India and the Ministry of Civil Aviation is telling. It indicates that the initial attribution may have been a preliminary guess based on passenger reports of shaking, which is a common reaction to hydraulic instability or autopilot corrections. As the investigation progresses, the focus will likely shift to whether the hydraulic failure was due to a manufacturing defect, maintenance oversight, or an external factor not visible in the immediate data.

The response from Airbus will be pivotal. If the failure was due to a systemic design flaw, it could trigger broader reviews of the A320 neo fleet. If it was an isolated incident, it will reinforce the robustness of the aircraft's redundant systems. For now, the passengers and the aviation community wait, with the understanding that this incident serves as a stark reminder of the complex interplay between mechanical reliability and human skill in modern aviation. The outcome of this investigation will undoubtedly influence how airlines monitor and report such rare hydraulic events in the future.