A post-flight fault log from an Air India Phuket-Delhi flight has revealed a cluster of nine warnings recorded within a minute during the August 4 incident in which the aircraft suddenly lost altitude and 24 people were injured.
The warnings on flight AI2379, an Airbus A320 registered as VT-EXO, included alerts linked to the aircraft’s hydraulic systems, flight controls and autopilot.
The incident has been classified as serious and is being investigated by the Aircraft Accident Investigation Bureau (AAIB).
Nine warnings appeared within a minute
According to the Centralised Fault Display System log reviewed by Hindustan Times, nine warnings appeared at around 9:32 am IST, when the aircraft had crossed the Odisha coast after flying over the Bay of Bengal.
The alerts included low pressure in the aircraft’s Green, Blue and Yellow hydraulic systems in different combinations. The log also recorded low reservoir levels in the Yellow and Blue systems, an autopilot disconnect and an elevator flight-control fault.
The aircraft’s hydraulic systems use pressurised fluid to transmit power and operate several major mechanical components.
The sequence of warnings was followed by two emergency-exit door sensor alerts at 9:33 am and 9:35 am.
No further hydraulic or elevator warnings were recorded for the next 43 minutes, according to the report.
Aircraft dropped around 360 feet
Data from Flightradar24 places the altitude change around the same period as the warning cluster.
The aircraft was flying at approximately 36,160 feet when an altitude anomaly was recorded at 9:33 am. It subsequently descended to around 35,800 feet, indicating a loss of about 360 feet.
The changing pressure readings across different hydraulic systems occurred within the same minute rather than showing one system remaining in a failed state.
According to the report, this pattern could be consistent with a temporary event, although the available fault log alone does not establish the cause of the altitude loss.
A sustained mechanical problem would generally be expected to produce additional or recurring warnings.
More warnings recorded later
The aircraft’s fault log also recorded an engine anti-ice fault at 10:16 am, followed by another autopilot disconnect at 10:52 am.
The second autopilot warning was not accompanied by hydraulic alerts, and the available log does not establish why the disconnect occurred.
The August 4 incident left 20 passengers and four crew members injured.
Pilot reportedly slept during flight
The incident has also drawn attention to the actions of the aircraft’s commander.
According to people familiar with the pilot’s account to investigators, he told the AAIB that he had slept for around 30 to 35 minutes during the flight before going to the washroom and returning to the cockpit.
The pilot reportedly then stood behind the first officer, who was operating the aircraft. The commander was acting as the pilot monitoring at the time, according to the account.
When the altitude event occurred, the commander was reportedly thrown onto the cockpit floor. A cabin crew member seated in the observer seat helped him back up.
The sequence described by the pilots has not been independently confirmed.
Pilot’s drug test also under scrutiny
The commander’s initial post-flight drug screening was reportedly recorded as “non-negative”, meaning the sample required further testing.
A subsequent confirmatory test reportedly returned positive for cannabis.
The circumstances surrounding the test and its relevance to the flight are part of the broader investigation. The available information does not by itself establish that the test result caused or contributed to the altitude event.
The AAIB investigation is expected to examine the aircraft’s technical data, crew actions, flight-control systems and other available evidence before determining what led to the incident.
