Aerospace
Airbus Reveals Why Air India AI2379 Suddenly Lost 300 Feet
An Air India Airbus A320neo operating flight AI2379 from Phuket to Delhi experienced a sudden loss of around 300 feet of altitude on August 4, 2026, during an event involving severe turbulence and high aircraft loads.
A preliminary assessment by Airbus indicates that the aircraft temporarily lost hydraulic pressure in its Green, Blue and Yellow hydraulic systems, resulting in the loss of elevator and aileron control for approximately four seconds.
The incident occurred on Air India flight AI2379, operating from Phuket International Airport (HKT) to Indira Gandhi International Airport (DEL). Injuries were reported among passengers and crew.
Airbus A320neo Temporarily Lost Flight Control
According to the preliminary Airbus assessment, the aircraft’s flight-control systems first detected a loss of pressure in the Green hydraulic system at around 04:02:44 UTC.
The Green system provides hydraulic power to several flight-control surfaces, including elevator, aileron and spoiler actuators.
About one second later, the aircraft also experienced a loss of pressure in the Blue and Yellow hydraulic systems.
This resulted in the temporary loss of control of all elevator and aileron surfaces.
The flight-control surfaces remained unresponsive for approximately four seconds before hydraulic pressure began returning.
Aircraft Developed a Nose-Up Tendency
During the temporary loss of hydraulic pressure, the elevators and ailerons moved into their designed damping modes.
Airbus recorded the right elevator drifting to approximately +0.6 degrees and the left elevator to around -1.0 degree.
At the same time, the ailerons moved toward a neutral position and reached approximately -13.6 and -13.1 degrees.
According to the preliminary assessment, these movements created a nose-up pitch tendency, contributing to the sudden change in aircraft altitude.
The aircraft’s second autopilot, AP2, also disconnected during the event.
A full nose-down command was subsequently applied from the First Officer’s side, but the flight-control surfaces initially did not respond because the hydraulic systems had not yet recovered.
Hydraulic Pressure Returned Within Seconds
The Blue hydraulic system recovered first, followed shortly by the Yellow and Green systems.
Once hydraulic pressure was restored, the aircraft’s flight-control surfaces became operational again.
Airbus currently considers the flight-control behavior to be a consequence of the temporary loss of hydraulic pressure, rather than evidence of a separate flight-control computer malfunction.
However, the investigation remains ongoing.
Faulty Green Hydraulic Pressure Switch Identified
One important finding in the preliminary assessment involves the Green hydraulic system pressure switch 1151GN.
The aircraft’s Auto Flight System identified a fault associated with this pressure switch.
The A320 flight-control computers receive hydraulic-system status from multiple sensing sources, including pressure switches and pressure transmitters. Airbus noted that at least two pressure-sensing sources detected low hydraulic pressure during the event, resulting in the shutdown of affected flight-control actuators.
Airbus has therefore requested detailed testing of the hydraulic pressure switches, pressure transducers and associated indication systems.
Airbus Orders Extensive Testing and Inspections
Because the aircraft experienced a significant altitude change and detected load exceedances, Airbus has requested inspections that go beyond routine hydraulic-system troubleshooting.
The requested actions include testing of the:
- Green hydraulic system
- Blue hydraulic system
- Yellow hydraulic system
- Hydraulic pressure switches and pressure transducers
- Automatic Flight System
- Flight Guidance and Flight Augmentation Computers
- Flight Augmentation Computers
- Electrical and hydraulic-related components
Airbus has also requested the removal and identification of pressure transducers and leak-measurement switches installed in the relevant aircraft area so that additional wiring and component checks can be performed if necessary.
Structural Inspection Also Required
One of the most important aspects of the investigation is the possibility of structural loads exceeding normal limits during the sudden altitude change.
Airbus has therefore requested that the aircraft undergo inspections under AMM 05-51-17 to determine whether the airframe experienced any damage or abnormal structural loading.
The airline has also been asked to provide detailed pilot reports describing what the crew observed during the event, along with records of hydraulic-system maintenance performed during the previous month.
Investigation Is Still Preliminary
Airbus has emphasized that the assessment is not a final investigation report.
The current findings are preliminary and further testing is required before the exact root cause can be established.
The investigation will examine both the aircraft’s hydraulic and flight-control systems as well as the possibility of structural effects caused by the sudden movement.
Additional inspections or corrective actions could be required depending on the results of the tests.
What Happened to Air India Flight AI2379?
In simple terms, the preliminary Airbus assessment indicates that Air India flight AI2379 temporarily lost hydraulic pressure in all three main hydraulic systems, causing the aircraft to lose elevator and aileron control for about four seconds.
The resulting flight-control behavior contributed to a sudden change in pitch and an altitude loss of approximately 300 feet. Hydraulic pressure then returned and normal flight-control capability was restored.
The investigation is continuing, and Airbus has not yet issued a final conclusion on the root cause of the incident.
Source: Airbus Customer Services, Dossier Reference 81849138 / Message 81849138/022. Preliminary assessment dated August 4, 2026.
Note: The Airbus assessment is preliminary and should not be treated as the final accident or incident investigation report.
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