Air Accident / Incident thread

The FMC does not do performance calculations. These calculations are done on a separate performance app, Boeing OPT, on a tablet/laptop. The calculated information from this is then entered manually into the FMC during preflight set up. It's at this stage errors can be made, so has strict SOP's to mitigate.

Coffeepls, that is clearly an AI generated fake with obviously wrong details, nonsensical grammar and impractical dates. It claims not calling go around was a factor, this was a take off....

It has been doing the rounds for the last day and is clearly a valid as a three euro note. Please delete or mods do the same.

Fuel contamination apparently, according to the FlightRadar thread on X, 'confirmed via ATC'

Dunno, I don't pay much attention to the speculating after an awful incident like that.

Yes absolutely incredible but that appears to be the case, particularly given the video evidence where the RAT is clearly deployed. It's not visually obvious but the audio is unmistakable. The RAT is an extremely loud piece of equipment, when we tested them in the hangar there was an advance warning twice over a tannoy that non essential personnel should vacate the building such was the deafening noise it produces.

Yet, you would expect to hear some evidence of the jet engines turning if they were producing thrust, particularly at takeoff power. In the Air India video all you can hear is the RAT. Combined with the sudden loss of lift, it seems fairly safe now to say that the engines were either not running (most likely considering the RAT would auto deploy in that case and there would not have been time for the crew to select the RAT on manually) or they were at idle.

I've been sent a whatsapp message purporting to explain exactly what happened. I believe the message is entirely fabricated. So fair warning; I believe the following is BS: It states that the FADECs both lost power during the transition from ground to air electrical config. It states route cause was BUS transfer failure due to arcing in the main power relay box brought on by corrosion due to electrical ground power connection and removal in torrential rain.

Nonsense, but it does raise the question: what would cause the RAT to deploy on rotation? The answer is a sudden loss of all electrical power. A "miracle on the Hudson" scenario is the first thing that jumps to mind, but there is no evidence of a bird strike at this stage. There is no smoke or tailpipe fire visible in the video, which you would expect with a strike of birds large enough to disable both engines. Fuel contamination is the next most plausible scenario in my mind. India is, in general, a very warm, humid country. It was 37c at the time of this accident. These are conditions which are ideal for microbial growth in fuel tanks. Modern jet fuel is treated with a biocidal additive that inhibits microbial growth in the tanks so that should not be an issue. Water in the tanks could be an issue, but that should be readily apparent and easily drained away. Fuel indications become erratic when there is water in the tanks so it's hard to believe it could be there in significant enough quantities to cause a dual engine flameout on rotation.

Whatever happened, happened on or very soon after rotation. I don't know the 787 very well so I can't say what happens on the transition from ground to air, systems wise, that could potentially end in this tragic scenario. Maybe someone else here can weigh in.

The other thing that I'm wondering is this: on Airbus aircraft it is standard procedure to leave the APU and APU bleed on for takeoff in temperatures over 30c. This helps with takeoff performance by removing the bleed air demand from the engines, thus increasing available thrust. Is this not a requirement on the 787? It wouldn't have helped in a dual engine failure scenario, but I believe it would have meant the RAT would not have deployed as the APU would provide electrical power (and presumably some form of hydraulic backup though I'm not sure on that?)

This is first and foremost an awful tragedy, and I know there are many who hate early speculation, but I can't help trying to understand what could have possibly caused such a catastrophic failure on takeoff.

RIP to all the lost souls.

Great info, thanks. In that case it would not be expected to have the APU running for takeoff.

The Airbus FCOM has a note in the standard before takeoff procedures about using APU bleed to improve performance/reduce maintenance costs, though it does not mention outside temperature so that is a company specific procedure.

"Consider setting the packs to OFF, or the APU bleed​ pb-sw to ON. This will improve performance, when using TOGA thrust. If a takeoff is performed with the packs OFF : The packs must be set to OFF at least 20 s before applying takeoff thrust. In the case of a FLEX takeoff, setting the packs to OFF, or the APU bleed​ pb-sw ON, will reduce takeoff EGT, and consequently reduce maintenance costs. Use of the APU bleed is not permitted, if wing anti-ice is to be used."

Absolutely right, and one of the reasons I said that the contents of that message were total nonsense, possibly created by AI.

Still to be verified but it looks like a catastrophic electrical failure on rotation.

Flight: AI-171 | Aircraft: Boeing 787-8 | Date: June 15, 2025 | Route: Ahmedabad (VAAH) → London Heathrow (EGLL)
Crash Site: ~1.2 km from VAAH Runway 23, post-V1 and rotation
Fatalities: 247 (243 onboard + 4 ground)
Survivors: 1 onboard survivors (alternate to original), 3 injured on ground

🛠️ AAIB Preliminary Report Highlights

1. Primary Cause – Electrical Power Transfer Interruption (PTI) During Rotation
   • During transition from ground to airborne electrical configuration, the aircraft experienced a cascading dual-engine FADEC (Full Authority Digital Engine Control) failure.
   • Root cause: Uncommanded bus transfer failure due to arcing in the main power relay box (PRB-A), traced to water ingress during pre-flight GPU disconnection in heavy rain.
   • This led to loss of electronic engine control at rotation, resulting in both GEnx engines rolling back to ground idle within 4–5 seconds.
2. Flight Data Record Timeline
   • +0:11 sec: Nose gear lifts off.
   • +0:13 sec: Sudden engine rollback begins. Thrust reduces from 92% N1 to <27% within 3 seconds.
   • +0:16 sec: Master caution + ENG FAIL L/R warnings. FO calls, “Both engines dropping!”
   • +0:20 sec: Autopilot and flight control reverts to Direct Mode. Pitch up attitude peaks at 18°.
   • +0:25 sec: Aircraft stalls at 186 ft AGL.
   • +0:30 sec: Full aerodynamic stall; nose drops rapidly.
   • +0:38 sec: Ground impact at 54° nose-down attitude, 174 knots.

Contributing Factors
• Environmental Conditions:
• Torrential rain during pushback.
• Moisture intrusion into PRB-A connector (P/N: HLN8471) — a known corrosion-risk component.
• Latent Maintenance Issue:
• Power transfer relay unit showed signs of thermal damage in a previous MEL deferral 2 weeks prior.
• No replacement had been conducted; aircraft was cleared under repetitive deferral.
• Design Oversight:
• Boeing 787 has no physical engine control backup (i.e., no direct mechanical linkage in FADEC loss scenario).
• Loss of power supply to both EEC channels resulted in engine “freeze” at ground idle instead of flameout.
• Flight Crew Response:
• Attempted engine relight sequence not completed before stall onset.
• Emergency power selector not activated — possibly due to confusion from multiple ECAM warnings.
✈️ Immediate Safety Actions
• DGCA + EASA + FAA Emergency AD issued within 24 hours:
• Mandatory PRB-A moisture integrity inspection on all Boeing 787 aircraft.
• Temporary restriction on dispatch with MEL items related to power transfer systems.
• Boeing:
• Issued Service Bulletin SB-787-24-212 requiring replacement of PRB-A connectors with sealed versions.
• Exploring addition of dual-path power redundancy for FADEC systems.
Lessons Learned
• Over-reliance on electrical power distribution architecture without layered redundancy.
• Lack of crew procedural training for full engine rollback during takeoff in EEC dual failure scenarios.
• Need for improved environmental sealing in GPU/electrical handover units in monsoon zones.
Human Toll
• The loss of 243 onboard lives, including 12 crew and 18 infants, deeply impacted the aviation community.
• Final words captured on CVR: “We lost everything – no thrust!”
• One family of five was killed on the ground in a hospital ambulance struck by debris.
Timeline – What’s Next?
• Aug 15, 2025: Release of FAA/Boeing electrical design audit report
• Sept 5, 2025: ICAO session on electrical-critical phase-of-flight risk mitigation
• Oct 2025: Mandated design retrofit across 787 fleet (rev. SB-787-24-219)

That's a version of a fake report that's being doing the rounds for a week or more. They just add in or subtract the latest buzz words. The fatality numbers are wrong. Preliminary reports do not indicate precise time lines of action probably because they are preliminary reports!

ICAO does not have sessions on electrical faults nor are they part of reports.

There was no heavy rain!

It's nonsense, wait for the real report and maybe think before you post.