Air India A320 Lost All Hydraulics, Dropped Nearly 300 Feet, Injuring 24

An Air India Airbus A320 briefly lost all three hydraulic systems and dropped nearly 300 feet during an August 4 flight from Phuket to New Delhi, injuring 20 passengers and four cabin crew members. The aircraft recovered within seconds and landed safely, but India’s Aircraft Accident Investigation Bureau has not determined why the three systems were lost or how they returned so quickly.

The interim findings also identify a separate pilot-fitness issue: the captain returned a non-negative result for an illegal psychoactive substance after landing. Investigators called that result a “serious concern,” but they did not find that the captain was impaired during the flight or connect the test result to the aircraft upset. The unresolved technical failure and the substance-test finding therefore remain two distinct investigative tracks.

What the aircraft recorded

The A320 departed Phuket at 1:41 UTC carrying 137 passengers and eight crew, with no abnormalities reported. At 4:02 UTC, its flight-control system detected the loss of the green hydraulic system. Detected losses of the blue and yellow systems followed within approximately four seconds.

The autopilot disconnected, a stall warning sounded and the aircraft deviated from its assigned altitude. It ultimately fell 292 feet below that level after first climbing above it. The pilots steadied the aircraft within about eight seconds, while the blue hydraulic system recovered first and the yellow and green systems returned shortly afterward.

The seat-belt signs were off when the upset occurred. Cabin damage included cracked or deformed ceiling panels, bent passenger-service panels, broken handrails, a damaged crew swivel seat and an uprooted toilet. After assessing the cabin, the crew continued to New Delhi, requested medical priority and landed safely.

Why three detected losses require deeper examination

The A320’s green, blue and yellow hydraulic networks are separate systems with independent reservoirs and no transfer of hydraulic fluid between them. They provide pressurized power for flight controls and other aircraft equipment. That separation is the core redundancy principle: losing one network should not automatically remove the others.

A sequence involving all three systems within seconds consequently demands more than a general hydraulic-failure label. Investigators still need to establish whether the aircraft experienced three physical pressure losses, erroneous or common sensor indications, an electrical or control-system event affecting what the computers detected, or another mechanism. Those are investigative questions, not established explanations.

The rapid recovery is equally important. A fault that disappears within seconds can be harder to isolate than a persistent component failure because the aircraft may operate normally during later ground checks. The recorded timing, cockpit warnings and flight-control response must be reconciled with examinations of the hydraulic components, fluid samples and associated aircraft data.

Investigators have removed flight-data and cockpit-voice recorders and collected hydraulic components, fluid samples, maintenance records and operational information. Airbus specialists have inspected the aircraft, while France’s BEA accident-investigation agency is assisting the Indian inquiry. Aviation adviser Mark Martin has criticized the interim findings as “ambiguous,” arguing that more engine data and explanation of the recovery should have been released. That is an attributed assessment, not an official conclusion.

The pilot test is serious but causally unconnected

Both pilots underwent post-flight medical checks. Their alcohol breath tests were satisfactory, while the captain’s psychoactive-substance screening and subsequent confirmatory blood test were non-negative. The co-pilot tested negative.

A confirmed substance-test result is an aviation-fitness and regulatory matter, but it does not by itself establish when the substance was used, the captain’s functional condition at the moment of the upset or a connection to the hydraulic-system indications. The interim report did not identify the captain’s actions as the cause of the altitude deviation, and the co-pilot was flying when the event began before the captain took control.

Air India has begun screening its more than 5,000 pilots. India’s Directorate General of Civil Aviation has also ordered one-time psychoactive-substance testing across airline pilot workforces, expanding beyond the existing requirement to test 10 percent of pilots and air traffic controllers randomly each year.

That response addresses pilot-fitness oversight, not the unanswered engineering problem. The final investigation will need to explain why three independent hydraulic networks were detected as lost within four seconds, why flight-control authority returned moments later and whether the recorded losses represented physical pressure failures or another system-level event. Until those questions are resolved, neither the hydraulic cause nor any relationship to the captain’s test result has been established.

By Thomas Caldwell — AMI’s senior editor for mechanical and mobility engineering, covering vehicle electronics, systems integration, electrification, chassis systems, propulsion, and safety policy.