Air India Phuket-Delhi flight: Technical failures, not turbulence, preceded 300-ft drop, sources say

The Air India Phuket-Delhi flight that experienced a sudden loss of altitude on August 4, injuring 17 passengers, was preceded by a cascade of technical failures involving the aircraft's hydraulic and flight-control systems, according to multiple sources familiar with the matter. This contradicts the airline's initial explanation that the incident was caused by turbulence.

Flight AI 2379, an Airbus A320 neo, took off from Phuket at 6.56 a.m. IST. Nearly two and a half hours later, at 9.32 a.m., the aircraft encountered a series of system failures. Sources said these included low-pressure indications and intermittent failures affecting one or two hydraulic systems at a time, with different combinations emerging as the problems escalated. This was followed by an autopilot disconnect and simultaneous fault alerts involving both the left and right elevators – the control surfaces that adjust the aircraft's nose up or down.

The A320 neo has three independent hydraulic systems that power critical functions such as primary flight controls, landing gear, nose-wheel steering, thrust reversers, flaps, slats, and braking. The automated post-flight maintenance report records failures in these systems, either individually or in pairs. One source who has seen the report said it logged nine such fault messages within a single minute.

As the aircraft pitched up and a stall warning triggered, one of the pilots took manual control and attempted to push the nose down, according to another source familiar with the sequence. The source said the pilot may have applied significant control input while trying to recover the aircraft, causing it to lose around 300 feet of altitude in a matter of moments. This sudden downward motion would have thrown passengers and crew upward, leading to injuries.

The available technical records do not show any further fault messages after this sequence. Sources indicated that the flight-control systems were restored following the pilots' intervention. However, the exact relationship between the technical failures, the flight-control response, and the subsequent altitude loss remains under investigation.

Despite the mid-air difficulties, the pilots chose to continue to Delhi rather than divert to a nearer airport. The decision was made because Delhi offered better medical facilities for the injured passengers and better access to aircraft engineering support.

The Ministry of Civil Aviation has said that the pilot-in-command's psychoactive substance screening test requires confirmatory testing, the result of which is awaited. Sources, however, said the commander was not at the controls at the time of the incident and had temporarily left his seat.

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 publicly mentioned the technical fault indications in their statements.

Air India's initial statement attributed the momentary loss of altitude to 'in-flight turbulence', but subsequent statements did not repeat that reference. The Ministry's statement also did not mention turbulence. Neither statement referred to any technical snags encountered during the flight.

Air India has sought a technical assessment from Airbus and is awaiting the manufacturer's response to a questionnaire related to the incident, according to sources. The specific technical issues referred to Airbus could not be independently confirmed.