Airbus Initial Findings: Air India A320 Lost Normal Flight Control for Four Seconds

What Airbus Says Happened on Air India Flight AI 2379

Airbus has delivered an initial technical readout of the August 4 Air India flight from Phuket to Delhi that left passengers and crew injured after a sudden altitude change. The manufacturer's assessment, based on the aircraft's digital flight data recorder, describes a rare and serious sequence: the A320's Green hydraulic system lost pressure first, followed by the Blue and Yellow systems. That removed powered operation of the elevators and ailerons for about four seconds.

According to the dossier, autopilot 2 was disconnected and full nose-down input began to be applied from the first officer's side. At first, the control surfaces did not respond in the normal way. The ailerons moved toward a zero hinge moment position, where they were no longer providing their usual control input, and the aircraft's nose moved upward. The hydraulic systems then recovered, the affected surfaces returned to normal operation, and the pilots regained control.

Airbus has not identified a definitive root cause for the pressure loss. The manufacturer has asked Air India to carry out operational tests of all three hydraulic systems, check pressure switches and pressure transducers, and remove and identify certain pressure transducers and leak-measurement switches. Further wiring checks may also be needed. Airbus said it is providing technical assistance to the relevant investigating authorities under ICAO Annex 13.

Why the Four-Second Hydraulic Loss Matters for Air India and the A320

Why a Four-Second Loss of All Three Hydraulic Systems Is an Alarm

The A320's hydraulic architecture is designed around redundancy: three independent systems power critical flight controls, so a single failure should not disable normal aircraft handling. Losing Green, Blue and Yellow in sequence is therefore not an ordinary fault. Even though the loss was temporary, the event effectively removed normal powered control of pitch and roll for several seconds. Airbus's description of the sequence supports treating this as a serious safety event rather than a minor technical hiccup.

The Cockpit Sequence Leaves the Root Cause Open

The dossier says the first officer's full nose-down input initially produced no direct response from the flight-control surfaces. That detail matters: the problem was not simply that the aircraft pitched up, but that the pilot's corrective input could not achieve normal control movement for several seconds. The aileron movement toward zero hinge moment and the resulting upward pitch are consistent with a loss of hydraulic authority, but they do not by themselves explain why all three systems lost pressure. Airbus has explicitly stopped short of naming a root cause.

Where the Investigation Must Go Next

Airbus's requested checks point toward pressure sensing and fluid-leakage components: pressure switches, pressure transducers and leak-measurement switches. That suggests investigators are first testing whether the pressure loss was real, sensed, or both. The mention of possible wiring checks also leaves open an electrical or sensor-signal explanation. Until those tests come back, this remains an aircraft-specific technical question, not yet a proven fleet-wide A320 issue.

The Concrete Checks Now Facing Air India and Other A320 Operators

For the parties directly involved, the next steps are specific and technical:

• Air India's engineering and maintenance teams should treat the Airbus-specified operational tests of the Green, Blue and Yellow hydraulic systems as the immediate work priority, followed by the removal and identification of the named pressure transducers and leak-measurement switches.
• Other A320 operators should not yet infer a fleet-wide problem. Until a root cause is confirmed, however, comparing recent pressure-switch and transducer fault history on their own A320s against this event may help identify any similar transient warnings.
• Investigating authorities should keep the August 4 event open as an active safety-data point: the final answer will depend on the component tests and the possible additional wiring checks Airbus has requested.