Airbus data confirms hydraulic, flight-control faults in Air India sudden drop incident
New Delhi: An Airbus dossier sent to Air India's engineering team has corroborated the hydraulic and flight-control abnormalities reported during the Phuket-Delhi flight on August 4, when the aircraft suddenly lost about 300 feet of altitude. The analysis is based on a preliminary readout of the aircraft's digital flight data recorder (DFDR).
The incident occurred on an Air India flight from Phuket, Thailand, to Delhi. According to the Airbus document, at 4:02:44 GMT (9:32 a.m. IST), the aircraft first recorded a loss of the hydraulic system. This coincided with the loss of the left-hand elevator — the horizontal surface on the tail that controls the aircraft's pitch, or nose-up and nose-down movement — as well as hydraulic-powered surfaces on the main wings that assist in roll control.
The very next second, the remaining two hydraulic systems also failed, resulting in a total loss of hydraulic-powered control surfaces, including the elevator and the wing ailerons. Airbus said that some of these flight-control surfaces were unavailable for around four seconds. During this period, the aircraft pitched up. The second autopilot then disconnected, and the First Officer applied nose-down control input, but the control surfaces did not respond immediately, according to the Airbus analysis.
About five seconds later, the hydraulic systems began recovering one by one, restoring the flight-control surfaces and their ability to respond to pilot inputs. These observations were part of Airbus's inputs to Air India's engineering team for troubleshooting the snags.
To understand the significance: hydraulic systems power the critical control surfaces that allow a pilot to steer and stabilise the aircraft. The elevator controls pitch, while the ailerons on the wings control roll. A loss of these systems can leave the aircraft temporarily difficult to control. Fortunately, the recovery of the systems prevented a more serious outcome.
As many as 24 people onboard were injured in the incident. The incident has since been classified as a "serious incident" by the Aircraft Accident Investigation Bureau (AAIB), which is investigating it. A three-member expert team from Airbus is in the country to examine the aircraft and its hydraulic systems.
Investigators will examine whether these were snags, false negatives, or events due to human intervention. The AAIB will also look into the sequence of failures and the pilots' actions during the emergency. The flight data and cockpit voice recorders have been decoded as part of the investigation.
Meanwhile, sources said the pilot-in-command of the flight tested positive for marijuana. This claim has not been officially confirmed by the airline or the regulator, and further tests are likely. The authorities are expected to treat the matter with due process.
