Pilots’ body writes to AAIB, flags timeline, RAT deployment in AI 171 preliminary crash report
The Federation of Indian Pilots (FIP) has challenged the Aircraft Accident Investigation Bureau’s (AAIB) preliminary report on the Air India Flight AI-171 crash, which killed 260 people. FIP suggests the deployment of the Ram Air Turbine (RAT) may have occurred before fuel interruption, potentially indicating an earlier electrical fault.
The accident involved a Boeing 787 aircraft, registration VT-ANB, operating from Ahmedabad to Gatwick. According to the Central Industrial Security Force, the tail section of the plane crashed onto the roof of a building in Ahmedabad on Thursday.
The FIP’s objections were detailed in a letter to the Director General of the AAIB, a body under the Ministry of Civil Aviation. This response followed a letter from D Michael Andrews, an advocate representing the affected passengers and their families.
Why is the timing of the Ram Air Turbine (RAT) disputed?
The FIP claims that simulator testing on the Boeing 787 contradicts the timeline provided in the AAIB’s preliminary report. While the AAIB report indicates RAT power generation occurred roughly 4–5 seconds after fuel interruption, the pilots’ body states simulator tests show it takes approximately 18 seconds.
The union argues this gap suggests the RAT deployment may be unrelated to fuel system changes. Instead, the FIP suggests the deployment could be a symptom of electrical faults that existed before any fuel disruption occurred.
Security camera visuals from Ahmedabad airport support this claim, according to the FIP. The union noted that the footage shows the RAT already deployed on the runway before the aircraft rotated for take-off.
What other anomalies preceded the crash?
The FIP letter highlights several events leading up to the accident that require further correlation with aircraft data. These include survivor reports of a loud bang and the dimming of cabin lighting.
Additionally, ACARS maintenance messages were transmitted between 0753 and 0808 UTC before take-off. The FIP pointed to damage visible in the aft EAFR image reproduced in the preliminary report as further evidence.
The pilots’ body requested that the AAIB examine these events collectively to determine if electrical system anomalies contributed to the crash.
What may happen in the final investigation?
The FIP has called for the AAIB to independently verify the acceleration recorded in the preliminary report. They also requested a verification of the relationship between RAT hydraulic power generation, RAT deployment, and fuel control switch movement.
A possible next step is the inclusion of these verified findings in the final report. The AAIB may need to reconcile the simulator data and airport security footage with the recorded flight data to establish a coherent sequence of events.
Frequently Asked Questions
Which aircraft was involved in the AI-171 crash?
The aircraft was a Boeing 787, registration VT-ANB.
What did the airport security cameras reveal?
According to the FIP, visuals showed the Ram Air Turbine (RAT) was already deployed on the runway before the aircraft rotated for take-off.
How many people died in the accident?
The crash killed 260 people.
Do you believe simulator data should carry as much weight as preliminary government reports in aviation investigations?