An Air India Airbus A320 flying from Phuket to Delhi suffered a sudden loss of altitude after multiple cockpit warnings indicated a possible stall, with an internal safety report revealing that the aircraft also recorded abnormal indications across its hydraulic systems.

Flight AI-2379, carrying 137 passengers and eight crew members, was operating on August 4 when the aircraft abruptly lost about 300 feet of altitude during cruise. At least 20 passengers and four crew members were injured in the incident.

The Directorate General of Civil Aviation (DGCA) has classified the episode as a serious incident, while the Aircraft Accident Investigation Bureau (AAIB) is examining what caused the aircraft to pitch sharply upward before the pilots carried out a stall-recovery manoeuvre.

Stall warning triggered

According to an internal Air India Flight Safety report accessed by NDTV, the captain was standing behind the first officer's seat and discussing the aircraft's air-conditioning system when multiple warnings appeared in the cockpit.

The aircraft's autopilot disengaged and its nose pitched upward. At the same time, aural warnings and alerts on the Electronic Centralised Aircraft Monitor (ECAM) indicated a stall condition.

The first officer, who was flying the aircraft at the time, responded with a standard stall-recovery action by pushing the nose down to regain airspeed.

The manoeuvre resulted in a sharp negative-g excursion, briefly causing the aircraft to experience conditions in which occupants and loose objects in the cockpit became effectively weightless.

Aircraft descended 300 feet

The captain's account in the report describes being thrown upward along with loose objects in the cockpit. He reportedly helped steady the first officer before moving back towards his seat.

Once strapped in, the captain took control of the aircraft and applied maximum continuous thrust to arrest the loss of airspeed and altitude.

The aircraft ultimately lost a maximum of approximately 300 feet before recovering.

An amber warning subsequently indicated that the aircraft had exceeded its negative-1g structural limit during the event.

Multiple hydraulic warnings recorded

The incident took a more serious turn when engineering data showed unusual indications from the aircraft's three hydraulic systems.

According to the report, the aircraft recorded low-pressure indications involving the Green, Blue and Yellow hydraulic systems within the same minute. The systems are designed to operate independently and provide redundancy for critical aircraft functions.

The aircraft also recorded an elevator fault and autopilot disengagement.

Investigators are examining whether a problem involving the elevator or hydraulic systems contributed to the sudden pitch-up that preceded the stall warning.

Hydraulic systems are crucial to an aircraft because pressurised hydraulic fluid powers several major functions, including flight-control surfaces, landing gear and braking systems.

Additional cockpit cautions appeared

After the aircraft stabilised, the crew notified air traffic control and began checking the various warnings.

A "door arm forward emergency" caution appeared on the ECAM and reportedly reappeared twice. The pilots followed the relevant manufacturer procedures and checklists before determining that the warnings could have been spurious.

A separate transient hydraulic caution was also recorded and cleared through the aircraft's reset procedure.

The pilots eventually decided to continue to Delhi and landed the aircraft safely.

Passengers and crew injured

Following the incident, the captain left the cockpit to assess the condition of passengers and crew members.

He was informed that several passengers and two cabin crew members had suffered serious injuries. Some cabin equipment was also damaged during the sudden aircraft movement.

The crew requested an ambulance, medical personnel and orthopaedic specialists to be available after landing. They also requested a parking position closer to the runway exit to facilitate the evacuation of injured passengers.

The aircraft eventually landed safely in Delhi.

AAIB, DGCA investigating incident

The AAIB has begun a detailed investigation into the incident under the framework of Annex 13 of the International Civil Aviation Organisation.

Airbus and France's Bureau of Enquiry and Analysis for Civil Aviation Safety (BEA) are providing technical assistance.

The Ministry of Civil Aviation said investigators are examining technical, operational, medical and human-factor evidence. This includes aircraft systems, recorded flight data, maintenance records, medical information and interviews with people connected to the incident.

The ministry has stressed that no final conclusion should be drawn until all available evidence has been examined.

Pilot drug-test reports emerge

The investigation has also drawn attention to the pilots' mandatory post-flight psychoactive substance screening.

According to sources cited in media reports, the first officer tested negative, while the captain reportedly failed two tests for marijuana.

Both pilots have reportedly been removed from flight duty pending further investigation.

The reported test results are separate from the technical investigation into the aircraft's sudden pitch-up, hydraulic indications and loss of altitude. Investigators are expected to examine all relevant operational and human factors before determining the cause of the incident.

Air India and ministry under scrutiny

Air India's outgoing CEO Campbell Wilson met senior Ministry of Civil Aviation officials following the incident.

Civil Aviation Minister Ram Mohan Naidu said aviation safety remains the ministry's highest priority and that the incident was being taken seriously.

The investigation will now focus on whether the aircraft's hydraulic and elevator indications were connected to the sudden pitch change, why the stall warning was triggered and whether any additional technical or human factors contributed to the event.

Until the AAIB completes its investigation, the precise cause of the 300-foot descent remains under examination.

The investigation into the Air India Phuket-Delhi flight that suddenly lost around 300 feet of altitude on August 4 has shifted attention from initial speculation about turbulence and the pilot's drug test to a possible chain of technical failures involving the aircraft's hydraulic and flight-control systems.

Air India flight AI2379, an Airbus A320 carrying 137 passengers and crew, was flying towards New Delhi when the sudden altitude change occurred roughly two-and-a-half hours after departure from Phuket. The incident left 17 people injured and prompted a formal investigation by the Aircraft Accident Investigation Bureau (AAIB).

While the exact cause remains under investigation, reports citing sources familiar with the probe have pointed to triple hydraulic-system failures, an autopilot disconnect and other temporary system indications on board the aircraft.

What Happened Mid-Flight?

The aircraft had reportedly been flying normally before the sudden incident. Passengers described an abrupt disturbance followed by intense shaking and a rapid drop in altitude.

Some passengers reported that cabin baggage and other objects were thrown around during the episode. Crew members instructed passengers to fasten their seatbelts as the aircraft experienced the sudden change.

The aircraft subsequently continued its journey and landed in Delhi, where injured passengers and crew members received medical attention.

The AAIB is investigating the sequence of events under the applicable international aviation investigation framework.

Focus Turns to Hydraulic Systems

One of the most significant developments in the investigation is the reported failure of all three hydraulic systems.

Aircraft hydraulic systems use pressurised fluid to operate and assist several critical components, including flight-control surfaces and other mechanical systems. Modern commercial aircraft are designed with multiple levels of redundancy, making a simultaneous failure of all three hydraulic systems an unusual event.

According to reports citing aviation sources, the cockpit crew responded to the problem by manually controlling the aircraft and temporarily changing its flight path or altitude.

The reported 300-foot descent may therefore have been part of the crew's response to the technical problem rather than an uncontrolled plunge.

Why Did the Aircraft Lose Altitude?

The precise sequence remains unclear.

Reports indicate that the aircraft's autopilot disconnected during the incident, requiring the co-pilot to regain manual control. Several cockpit indicators or switches were also reportedly observed to change temporarily.

If confirmed by investigators, the combination of hydraulic-system problems and an autopilot disconnect could help explain why the aircraft experienced a sudden change in altitude.

However, investigators will need to establish whether the hydraulic failures occurred simultaneously, whether one system failure triggered another and how the aircraft's flight-control systems responded.

What About the Pilot's Drug Test?

The pilot's initial psychoactive-substance screening has also attracted attention.

The Civil Aviation Ministry said the initial screening produced a result that required further analysis and that a confirmatory test was being conducted. The final result had not been established at the time of the reports provided.

The Airline Pilots Association of India has also pointed out that some commonly used medicines can potentially affect preliminary screening results.

Therefore, the initial "non-negative" screening should not be treated as proof that the pilot was intoxicated or that it caused the altitude loss.

Investigators will have to consider the confirmatory test alongside cockpit recordings, aircraft data and other evidence.

Turbulence Theory Also Under Review

Turbulence was initially cited in Air India's description of the incident. However, subsequent statements reportedly did not place the same emphasis on turbulence.

This has raised questions about whether turbulence was actually responsible for the altitude loss or whether the aircraft's technical problems played the central role.

Only the formal investigation can establish whether turbulence, a technical malfunction or a combination of factors contributed to the event.

Airbus Joins the Investigation

Aircraft manufacturer Airbus is assisting the investigation.

The company has said it is providing technical assistance to the relevant authorities in accordance with ICAO Annex 13 and is sending specialists to support the probe.

Investigators are expected to examine the aircraft's flight-data recorder, cockpit voice recorder, maintenance records and relevant system data. These sources should help establish exactly what happened inside the aircraft during the critical seconds.

The investigation will also examine whether the reported hydraulic failures occurred before or after the altitude change and how the cockpit crew responded.

What Happens Next?

At this stage, several explanations remain possible, but none has been conclusively established.

The investigation will need to determine the relationship between the reported triple hydraulic failure, autopilot disconnect, cockpit indications, the aircraft's 300-foot altitude change and the injuries sustained inside the cabin.

The pilot's confirmatory test will also be important in determining whether the preliminary screening has any relevance to the incident.

Until the AAIB completes its investigation, claims that the aircraft plunged because of pilot intoxication or turbulence remain unproven.

For passengers, however, the incident has once again highlighted the importance of keeping seatbelts fastened throughout a flight, including when the aircraft appears to be flying normally.

An Air India flight travelling from Phuket to New Delhi experienced a sudden loss of approximately 300 feet in altitude during cruise, prompting a formal aviation-safety investigation and additional testing of the pilot-in-command.

The incident occurred on August 4 aboard Air India flight AI2379, operated by an Airbus A320 registered as VT-EXO. The aircraft stabilised after the altitude loss and later landed safely in Delhi.

According to the Ministry of Civil Aviation, the flight was carrying 137 passengers—including three infants—and eight crew members. A few passengers and cabin-crew members reportedly suffered injuries during the incident. The ministry did not disclose their condition or the exact nature of the injuries.

Initial Screening Not a Final Finding

Both pilots underwent the prescribed psychoactive-substance screening as part of the standard procedure followed after such incidents.

The pilot-in-command’s initial screening produced a result requiring confirmatory testing. Samples have been sent to a designated laboratory, and the final report is awaited.

The preliminary result must not be described as a confirmed positive drug test. The ministry has also not disclosed which substance, if any, may have been indicated.

The Directorate General of Civil Aviation has removed both pilots from the flying roster while the investigation continues.

AAIB Investigating ‘Serious Incident’

The occurrence has been classified as a “serious incident” and is being investigated by the Aircraft Accident Investigation Bureau.

Air India said it was aware that the pilots had undergone post-flight screening but had not been informed of the results. The airline said it would cooperate with the investigating authorities.

The investigation will examine the aircraft’s flight data, cockpit actions and possible technical or operational factors behind the sudden altitude loss.