An Air India flight from Phuket to Delhi experienced a sudden altitude loss on August 4, with a post-flight fault log revealing that the aircraft recorded nine warning messages within just one minute. The incident, which injured 24 people, is now being investigated by the Aircraft Accident Investigation Bureau (AAIB).
Nine Warnings Recorded in 60 Seconds
The aircraft involved was Air India flight AI2379, an Airbus A320 registered as VT-EXO. According to the Centralised Fault Display System (CFDS) log reviewed by Hindustan Times, nine warnings appeared at around 9:32 am IST while the aircraft was flying over the Bay of Bengal after crossing the Odisha coast.
The warnings included indications of low pressure in the Green, Blue and Yellow hydraulic systems, low reservoir levels in the Blue and Yellow systems, an autopilot disconnect and an elevator flight-control fault.
Hydraulic systems are critical to an aircraft because pressurised fluid is used to transmit power to several major mechanical and flight-control components.
Aircraft Lost Around 360 Feet
Flight-tracking data indicates that the aircraft was flying at approximately 36,160 feet when an altitude anomaly was recorded at about 9:33 am. It subsequently descended to roughly 35,800 feet, representing a loss of around 360 feet.
The sudden movement caused injuries to 20 passengers and four crew members. The flight eventually continued to Delhi and landed safely, while the incident was classified as serious and referred for investigation.
Were the Hydraulic Warnings Caused by the Altitude Drop?
The sequence of warnings has raised questions about the relationship between the aircraft’s sudden movement and the hydraulic alerts.
Interestingly, the warnings showed changing pressure readings across different hydraulic systems within the same minute rather than evidence of one system remaining in a failed condition. According to an assessment of the log against standard A320 fault references, a sudden vertical movement could temporarily cause hydraulic fluid to shift inside the reservoirs and trigger such readings.
No further hydraulic or elevator warnings were recorded for the following 43 minutes. An engine anti-ice warning appeared at 10:16 am, while another autopilot disconnect was recorded at 10:52 am without accompanying hydraulic warnings.
Questions Over Cockpit Events
The investigation has also turned attention to what happened inside the cockpit before and during the altitude change.
According to people familiar with the commander’s account to investigators, the pilot said he had slept for around 30 to 35 minutes during the flight. He reportedly went to the washroom and later returned to the cockpit, where the first officer was operating the aircraft. The commander was acting as the pilot monitoring when the altitude event occurred.
The commander reportedly told investigators that he was discussing the aircraft’s air-conditioning system when the sudden movement occurred and that he was thrown onto the cockpit floor. A cabin crew member helped him back up.
However, investigators have not independently established the complete sequence of events inside the cockpit based solely on the pilots’ accounts.
Pilot’s Drug Test Under Investigation
The case has also drawn attention to the commander’s post-flight drug screening. His initial screening was reportedly recorded as “non-negative”, meaning it required further testing. A subsequent confirmatory test reportedly returned positive for cannabis.
The finding is part of the wider investigation, and it should not by itself be treated as proof that the test result caused the aircraft’s altitude event.
AAIB Investigation Continues
The nine warnings, the temporary hydraulic pressure indications, the autopilot disconnect and the elevator fault are now among the elements being examined as investigators reconstruct the incident.
While the available data points to a brief and unusual event rather than an obvious sustained hydraulic failure, the final cause has not yet been established. The AAIB investigation is expected to provide a clearer picture of what triggered the sudden altitude change and how the aircraft systems and crew responded.
The incident highlights the complexity of modern aircraft systems and the importance of examining flight-data records, cockpit accounts and technical warnings together before drawing conclusions about what happened.
