Air India is putting its finest under fresh scanner

The incident, initially described as turbulence, is under investigation.

Airbus’ preliminary assessment, first reported by ET on Friday, found that the aircraft temporarily lost hydraulic control across all three of its independent hydraulic systems, leaving key flight controls unresponsive for several seconds.

The incident resulted in injures for passengers and crew, and prompted an investigation by the Aircraft Accident Investigation Bureau, with Airbus assisting in the probe.

What happened on the Phuket-Delhi flight

The aircraft’s three independent hydraulic systems, known as the Green, Blue and Yellow systems, are designed to ensure that the failure of one system does not compromise the aircraft’s ability to remain under control.

However, data from the flight recorders indicated that pressure dropped across all three systems within about one second during the incident. The loss of hydraulic control temporarily affected the aircraft’s elevators and ailerons, which are critical flight-control surfaces.

The ailerons moved in the same direction rather than in opposite directions, generating additional lift and causing the aircraft’s nose to pitch sharply upwards without pilot input. The autopilot then disengaged, as it is designed to do during abnormal conditions.

The first officer took manual control and pushed the aircraft’s nose down. The resulting rapid downward acceleration caused passengers and cabin crew to be thrown upwards, resulting in injuries. Hydraulic pressure returned across all three systems about five seconds later, after which the flight-control computers reconnected and the aircraft again responded to pilot commands.

It has not yet been established whether the hydraulic systems themselves malfunctioned or whether a faulty wire or sensor generated a spurious warning. Airbus has asked Air India to physically inspect one of the hydraulic pressure switches to determine whether it was faulty and transmitted an incorrect signal.

The incident has been classified as a serious incident by the government and is being investigated by the AAIB. The initial flight-recorder assessment did not indicate any human action as the cause of the incident.

Two more pilots return non-negative drug test results

The latest scrutiny comes alongside Air India’s expanded testing of cockpit crew for psychoactive substances. Two more Air India pilots have reportedly returned “non-negative” results in initial drug tests conducted after the Phuket incident, according to people aware of the development.

Confirmatory test results are awaited, and the pilots have been taken off flying duties pending the final reports. Nearly 400 pilots have undergone screening so far under Air India’s one-time mandatory testing programme covering cockpit crew across Air India and Air India Express. The group has more than 5,000 pilots.

A non-negative initial result does not by itself establish that a pilot has consumed a prohibited substance. Confirmatory testing is required because initial results can sometimes be affected by legitimate therapeutic treatment or substances such as pain-relief medication. Confirmatory analysis can involve high-complexity techniques, including spectral analysis of hair samples.

Air India had mandated all pilots and cabin crew to undergo testing for psychoactive substances from last Thursday, going beyond the civil aviation regulator’s existing requirements.

The captain of the Phuket-Delhi flight had separately come under scrutiny after returning a non-negative result in an initial test. However, the preliminary assessment of the flight data recorders did not indicate any human action as the cause of the aircraft’s sudden altitude loss.

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