Human error: Experienced pilot shares preliminary assessment

A user of X (formerly Twitter), who claims to be a pilot with more than 15,000 hours of flying experience, shared his prima facie assessment of what went wrong in the Boeing 787-7 Dreamliner flight from Ahmedabad to London. The assessment by the user who calls himself "Iven's Dad" suggests "human error" as the most probable cause, specifically an insufficient flap setting and inadequately selected thrust during takeoff, which aligns with preliminary observations of the aircraft's low speed and high angle of attack.

The crash of Air India Flight AI171 occurred on June 12, shortly after takeoff from Ahmedabad, resulting in 241 fatalities out of 242 people on board, and several dead on the ground in the building where the aeroplane crashed, which housed many medical students and doctors, marking a devastating aviation disaster.

Boeing's recent history includes a deal with the US government to avoid criminal responsibility for earlier crashes in 2018 and 2019, which might influence public and regulatory scrutiny following this incident.

The involvement of a Boeing 787 Dreamliner in the fatal crash is notable, as it is the first such incident for this model, which might lead to increased examination of the manufacturer's production and safety practices.

The assessment considers technical factors like the speed-drag curve and the impact of not retracting the landing gear. These are critical to understanding the sequence of events leading to the crash.

The possibility of an incorrect takeoff weight input into the flight management system is mentioned in the X post, which could have resulted in inadequate thrust and speeds, a scenario that requires further investigation to confirm.

The crash has prompted international responses, including support from the UK government and the activation of an Operational Control Room by the Indian Ministry of Civil Aviation, indicating the global import of the incident.

How good is the assessment?

The assessment by 'Iven's Dad' appears technically sound, based on the information available as of now.

1. Experience and expertise: Iven's Dad claims to be an airline pilot with over 15,000 hours of experience, which lends credibility to the analysis. The mention of a physics institute background further suggests a strong understanding of aerodynamics and flight mechanics.
2. Preliminary analysis: The assessment is explicitly labelled as preliminary, which is appropriate, given the limited information available shortly after the crash. This cautious approach is important in aviation incident analysis.
3. Technical observations:
   • Flap setting: The observation that the flaps were only slightly extended (presumably to position 1 instead of 5) is critical. Flaps are used to increase lift during takeoff, and an insufficient setting can lead to reduced lift and increased drag, contributing to the aircraft's inability to gain altitude.
   • Landing gear: The note that the landing gear was still extended is significant. Extended landing gear increases drag, which would exacerbate the aircraft's struggle to maintain altitude and speed.
   • Angle of attack: A high angle of attack without sufficient speed can lead to a stall, which is consistent with the observed behaviour of the aircraft.
   • Engine noise and visuals: The lack of visible smoke or fire and low engine noise suggests that engine failure is less likely, focusing the analysis on aerodynamic and human factors.
4. Human error hypothesis: The suggestion that human error, specifically in flap settings and thrust selection, is the most probable cause aligns with historical data on aviation accidents. The majority of aviation incidents are attributed to human factors, often due to misconfiguration or misjudgment during critical phases like takeoff.
5. Additional considerations: The possibility of an incorrect input of takeoff weight into the Flight Management System is a plausible scenario that could lead to miscalculated thrust and speeds. The prioritisation of making an emergency call over flying the aircraft is a common issue in high-stress situations, which could have compounded the problem.
6. Contextual support: The Squirrels conducted a web search, the results from which corroborate some aspects of the assessment:
   • The Boeing 787 Dreamliner involved in this crash is noted as the first fatal incident for this model, which heightens the scrutiny on operational procedures.
   • The historical context of Boeing's recent deals and safety concerns might influence how this incident is perceived, but it doesn't detract from the technical analysis itself.
7. Limitations acknowledged: Iven's Dad emphasises the preliminary nature of the assessment and the low confidence level, which is responsible and aligns with standard practice in incident investigation, where full data is not yet available.

The assessment is technically sound for a preliminary analysis, focusing on plausible aerodynamic and human factors that could have led to the crash. However, as with any preliminary assessment, it should be considered alongside ongoing investigations and additional evidence that may emerge.

The involvement of official bodies like the Indian Ministry of Civil Aviation and international support indicates that a thorough investigation is underway, which will ultimately provide a definitive cause.