New Delhi: A preliminary analysis by Airbus has found that an Air India Airbus A320neo suffered a simultaneous loss of key flight control surfaces for about four seconds during a flight from Phuket to New Delhi, according to a report by NDTV.

The aircraft experienced multiple failures involving all three of its hydraulic systems, leaving its elevators and ailerons without hydraulic power. The spoilers were also lost during the incident.

What happened during the four-second loss of control?

The elevators control the aircraft's pitch, while the ailerons help control its roll. Spoilers can reduce lift and increase drag, helping an aircraft descend or slow down.

According to the initial Airbus analysis, the elevators and ailerons of the A320neo drifted without corresponding pilot commands for around four seconds after the hydraulic failures.

The aircraft's autopilot then disconnected. The co-pilot, who was flying the aircraft at the time, pushed the side-stick forward after stall warnings were believed to have been generated in the cockpit.

With the hydraulic systems unavailable, however, the control input did not immediately produce the expected nose-down movement. The aircraft regained hydraulic power within a few seconds, after which the control surfaces responded.

The resulting sudden nose-down movement caused injuries to several passengers and cabin crew, with some people reportedly being thrown towards the roof of the aircraft.

Airbus initially pointed to hydraulic pressure sensor

The aircraft, which was around 7.8 years old, transmitted data to Airbus' technical support centre, AIRTAC, in Toulouse, France.

Some information may have been transmitted through ACARS, the Aircraft Communications Addressing and Reporting System. The full Digital Flight Data Recorder data was also likely downloaded after the aircraft landed and sent to Airbus for analysis.

Airbus' initial findings were sent to Air India shortly after midnight on August 5, around 15 to 16 hours after the incident.

The preliminary assessment pointed to a possible fault involving a hydraulic pressure sensor or pressure switch. However, Airbus did not establish a definitive root cause at that stage and did not issue final recommendations.

Airbus and French investigators examine aircraft

Experts from Airbus and France's aviation accident investigation agency, the BEA, have since arrived in New Delhi and examined the aircraft and its systems.

New findings from the preliminary physical inspection have been forwarded to India's Aircraft Accident Investigation Bureau (AAIB), which is overseeing the investigation, according to NDTV.

The investigation is continuing, and the initial Airbus findings do not establish a final cause for the loss of control.

Pilot's drug test also under investigation

The conduct of the pilot in command, Captain Sudeep Vashistha, is also being investigated separately. Vashistha failed two urine tests conducted after the aircraft landed, with marijuana detected in his system.

A cabin crew member is also believed to have filed a complaint alleging that the pilot had previously smoked marijuana.

There is currently no finding linking the pilot's alleged drug use to the serious safety incident on the Phuket-Delhi flight.

Following the positive marijuana test, Air India ordered mandatory tests for pilots across Air India and Air India Express to check for banned substances or medications in their systems.

The technical investigation into the aircraft's hydraulic-system failure and the circumstances surrounding the sudden loss of control is continuing.