Pilots' body flags timeline, RAT deployment in AI171 crash report
What's the story
The Federation of Indian Pilots (FIP) has raised concerns over the preliminary report of the Air India Flight AI171 crash. The pilots' body has written to the Aircraft Accident Investigation Bureau (AAIB), questioning the timeline and Ram Air Turbine (RAT) deployment details. The AAIB's preliminary report states that RAT started generating hydraulic power around four to five seconds after fuel supply was interrupted. However, simulator tests cited by FIP indicate that this process takes about 18 seconds.
Discrepancy revealed
RAT deployment may have occurred before fuel control switch movement
The pilots' body believes this discrepancy is crucial, as it could mean that the RAT deployed before the fuel control switches were moved. "The letter therefore suggests that RAT deployment may have occurred before fuel control switch movement and may indicate an earlier system or electrical fault requiring further investigation," the letter read. The RAT is a backup device that deploys in emergencies to provide hydraulic power using airflow from the aircraft's speed.
Visual evidence
FIP questions visual evidence in preliminary report
FIP has also questioned photographs and CCTV footage cited in the preliminary report. They argue that some images appear to show the RAT deployed shortly after take-off, and airport security camera footage from Ahmedabad may show it even before the aircraft took off. The pilots' body wants investigators to analyze this visual evidence with flight data recordings.
Crash analysis
FIP calls for closer examination of various factors
Apart from RAT timing, the pilots' body has also highlighted differences in simulated take-off speeds and those mentioned in the preliminary report. They have called for a closer examination of survivor accounts describing a loud bang, cabin lights dimming before the crash, ACARS maintenance messages transmitted before the accident, flight data recordings, and visible damage captured in photographs cited in the report.
Verification request
FIP demands fresh simulator tests, independent verification
The FIP has requested the AAIB to independently verify the aircraft's rate of acceleration during takeoff, timing of RAT deployment, when hydraulic power was available, and when fuel control switches were moved. They have also asked for fresh Boeing 787 simulator tests with an observer nominated by them. The AAIB's final report will officially determine the cause of the AI171 crash using flight data recorder information and other evidence.