Simulator Tests Challenge Official Fuel Cut-Off Theory in AI171 Crash
The Federation of Indian Pilots (FIP) on Friday challenged key findings of the preliminary investigation into the Air India Flight 171 crash, claiming that fresh simulator tests raise serious questions over the official theory that the aircraft went down after the pilots deliberately cut off fuel to both engines.
Addressing a press conference in Mumbai, FIP president Captain CS Randhawa said the federation had conducted 10 tests on an EASA-certified Boeing 787 simulator under conditions replicating the aircraft's weight, balance and operating environment on the day of the crash. According to him, the results do not support the timeline outlined in the Aircraft Accident Investigation Bureau's (AAIB) preliminary report.
Dispute Over Ram Air Turbine Deployment
At the centre of the dispute is the deployment of the Ram Air Turbine (RAT), an emergency backup system that automatically extends to provide hydraulic and electrical power during critical failures. The AAIB's preliminary findings suggested that the RAT deployed within seconds after fuel supply to the engines was cut off. However, Randhawa claimed the simulator tests showed that a manual fuel shut-off would take around 18 seconds before the RAT could deploy and restore hydraulic pressure.
"If our tests are correct, then the timeline mentioned in the preliminary report simply does not add up," Randhawa said, adding that the four-second interval cited by investigators was not supported by the simulator data generated during the federation's trials.
Possible Electrical Malfunction
The pilots' body argued that the rapid deployment of the RAT could instead indicate a major electrical malfunction that occurred before the engines lost power. According to the federation, such a failure could have triggered a chain of events that ultimately led to the crash.
In support of its claim, the FIP pointed to accounts from the lone survivor of the accident, who reportedly described the cabin lights flickering moments before the aircraft began losing altitude. The federation said such observations were consistent with a sudden loss of electrical power rather than a deliberate fuel shut-off.
History of Electrical Issues
Randhawa also claimed that the aircraft involved in the accident had a history of electrical issues prior to the fatal flight, raising further questions about whether a broader technical problem was adequately examined during the investigation. The federation further alleged that Captain RS Sandhu, whom it described as one of India's most experienced Boeing 787 pilots, was kept away from crucial stages of the investigation despite his expertise on the aircraft type.
Without directly accusing investigators of misconduct, Randhawa questioned why alternative technical explanations were not being examined with equal rigour. He said conclusions affecting the reputation of deceased pilots should be backed by evidence that can withstand technical scrutiny.
Demand for Independent Verification
The FIP said it has shared its simulator findings with Boeing as well as the Indian aviation authorities and has sought a detailed review of the discrepancies it claims exist between the simulator data and the preliminary report. Demanding greater transparency, the federation called for the final accident report to be withheld until the RAT deployment timeline and other technical issues are independently verified. It also urged authorities to include Captain Sandhu in the investigative process to ensure what it described as a fair and technically sound assessment of the evidence.
