Air India crash

[onetrack]

6 hours ago, Gazunda61 said:

It had nothing at all to do with FADEC - which is the engine control. It was an ADIRU (Air Data/Inertial Reference Unit) issue - which has never been established conclusively how it occurred. Interference from the Holt VLF station was not a factor 

Yes, my apologies, I was going on my faulty memory, thinking FADEC instead of ADIRU, and I should've checked the official incident summary before posting.

 

The Incident Summary for VH-QPA, 07/10/2008:

 

"The official investigation into the incident concluded that the accident 'occurred due to the combination of a design limitation in the flight control primary computer (FCPC) software of the Airbus A330/Airbus A340, and a failure mode affecting one of the aircraft’s three air data inertial reference units (ADIRUs). The design limitation meant that, in a very rare and specific situation, multiple spikes in angle of attack (AOA) data from one of the ADIRUs could result in the FCPCs commanding the aircraft to pitch down'."

 

Yes, no conclusive proof of the cause was ever derived - from the available evidence. That evidence was lacking, because the U.S. Navy refused to reveal what type of radio transmissions are generated from the Holt VLF station. They merely state their transmissions don't affect aircraft systems.

But what are the chances of TWO separate incidents, involving TWO different makes of aircraft, BOTH happening in the vicinity of the Holt VLF station? And what exactly is that "very rare and specific situation"?

 

"On 27 December 2008, a Qantas A330-300 aircraft operating from Perth to Singapore was involved in an (uncommanded control) occurrence, 350 nautical miles (650 km) south of Learmonth Airport while flying at 36,000 feet. At this time, the autopilot disconnected. The crew actioned the revised procedure released by Airbus after the earlier accident, and returned to Perth uneventfully."

 

Edited Thursday at 12:13 PM by onetrack

[Blueadventures]

9 hours ago, onetrack said:

Another point is that India is the home of some pretty destructive critters, such as rats. If a rat got aboard undetected and chewed up important electrical componentry or wiring, and thus damaged redundancy features as well, that would go a long way to explain how "foolproof" aircraft systems could be damaged to the point where redundancy failed.

Bit like the Cockatoo that chewed wiring on the Gilmore Rocket at Bowen.

[onetrack]

15 minutes ago, Red said:

Unusual to give such a definite timescale, where did you read that?

The Chairman of TATA Sons/Air India, N. Chandrasekaran, has stated he expects to hear some preliminary crash findings within a month.

 

 

[onetrack]

There's an interesting previous incident in 2020, involving a B787-8 Dreamliner on descent into Kansai International Airport, Osaka, Japan, when at 15,000 feet, the flight crew of Jetstar Airways flight JQ15 received an engine thrust warning on the number 2 engine, which subsequently started to surge. The crew then received an engine fail indication on the number 1 engine, without any shift in parameters indicating any engine power loss.

That warning was followed by an engine fail warning on the number 2 engine. The number 2 engine auto relight activated, and the engine continued to surge during the descent.

High concentrations of biocide in outer tanks resulted in magnesium salt residue jamming fuel controls at low fuel flows, so both engines momentarily dropped below idle on descent.

 

The conclusion of investigators was that a dose of biocide containing magnesium salts was poured into the outer wing tanks, but this dose of biocide didn't mix properly with the fuel in other tanks (or it was an inaccurate dosage), and the high concentration of the magnesium salts caused the fuel metering spools to become impeded in their travel range and thus caused fuel supply disruptions to the engines. Same type of aircraft, and same types of engines.

 

https://asn.flightsafety.org/wikibase/223675#:~:text=As for the higher accumulation,was fed to the engines.

[facthunter]

The extended time is from many sources and is related to high temperature damage to the recorders.   TATA took over ownership of Air India which was not doing well financially. This latest thing if found to be a preventable error won't help. TATA is a big show. Nev

[facthunter]

 Microbial contamination of avtur is a common issue. The extremes of temperature don't kill it. The additive is toxic. Nev

[onetrack]

The latest information is one of the two black boxes has sustained damage. The Indians state the damage is from "a fall", and from fire. I get the impression the outside casing has suffered extensive damage, no doubt from impact and post-crash fire, which is making the Indians jittery about opening it, and potentially losing critical data.

 

They are weighing up whether to attempt opening it (obviously with advice from the likes of the NTSB and Boeing), or whether to send the damaged black box to Singapore, or the U.S., where there is more extensive knowledge and experience available, when it comes to opening damaged black boxes and extracting the data.

 

https://www.ndtv.com/india-news/exclusive-air-india-flights-black-boxs-outer-surface-damaged-after-fall-8713835

[onetrack]

Further to my suggestion that a rodent on board Flight 171 could be responsible for electrical damage leading to the crash - I find that the crash aircrafts, sister aircraft (VT-ANA), was involved in a flight diversion when a rat was spotted on board, mid-flight, in 2015.

 

That reported rat was never found after landing. It is significant, IMO, that other Air India aircraft have had rodents on board. They enter via catering vans, and once on board, food dropped by passengers keeps them alive. Rats need to chew constantly to keep their teeth to a healthy length, as their teeth grow constantly. A rat chewing wiring on a fly-by-wire aircraft is the stuff of nightmares.

 

https://timesofindia.indiatimes.com/india/four-hours-into-journey-rat-grounds-air-indias-milan-flight/articleshow/48288464.cms

[danny_galaga]

10 minutes ago, onetrack said:

Further to my suggestion that a rodent on board Flight 171 could be responsible for electrical damage leading to the crash - I find that the crash aircrafts, sister aircraft (VT-ANA), was involved in a flight diversion when a rat was spotted on board, mid-flight, in 2015.

 

That reported rat was never found after landing. It is significant, IMO, that other Air India aircraft have had rodents on board. They enter via catering vans, and once on board, food dropped by passengers keeps them alive. Rats need to chew constantly to keep their teeth to a healthy length, as their teeth grow constantly. A rat chewing wiring on a fly-by-wire aircraft is the stuff of nightmares.

 

https://timesofindia.indiatimes.com/india/four-hours-into-journey-rat-grounds-air-indias-milan-flight/articleshow/48288464.cms

Do rats only go on board Air India flights? 

[Marty_d]

18 minutes ago, danny_galaga said:

Do rats only go on board Air India flights? 

No, usually they fly Air Force One

[onetrack]

41 minutes ago, danny_galaga said:

Do rats only go on board Air India flights? 

No, they're a problem worldwide, but the so-called "Third World" countries have an increased rodent problem due to the higher level of general rubbish and lax collection of that rubbish.

[danny_galaga]

8 hours ago, onetrack said:

No, they're a problem worldwide, but the so-called "Third World" countries have an increased rodent problem due to the higher level of general rubbish and lax collection of that rubbish.

I see what you're saying. India is not a third world country though. Good to keep it all factual.

[Thruster88]

9 hours ago, onetrack said:

No, they're a problem worldwide, but the so-called "Third World" countries have an increased rodent problem due to the higher level of general rubbish and lax collection of that rubbish.

Not sure about the live rat idea. If a rat started chewing on the wires in a canbus or digital type system there would be error messages, many error messages before takeoff. Left and right side of the aircraft are two essentially separate systems. Synchronised left and right side rats? anything is possible.

 

The aircraft was 12? years old so would have been through many inspections. 

[facthunter]

Lots of redundancy in the electrics.  Nev.

[kgwilson]

I  always understood that the CVR & FDR were located in the tail section of the aircraft as this is the least likely place to suffer severe damage in a crash. The tail section got torn off & stuck in the first building so unless the units are further forward in a 787, you'd think that they should be in reasonable condition & not fire damaged.

[onetrack]

Danny - India may be quite advanced in some areas, but as far as rubbish generation and failure to collect it, they're still third world.

 

FactHunter - Yes, redundancy in electrics on aircraft would certainly be well addressed, but every LAME with electrical knowledge would quite likely assert that all bets are off once a rodent starts chewing on electrical components.

 

Thruster88 - I'm not so sure about the early warning via error messages. It would only take destruction of wiring to the engine fuel valves to cause double engine failure. A rodent biting into a high voltage aircraft harness would cause a major short circuit instantly. A major short circuit would trip circuit breakers and shut down critical systems at a critical time.

[onetrack]

India's Ministry of Civil Aviation is a bit annoyed with media reports that their ability to read the black boxes is inadequate, and they will be sent to the U.S. or Singapore for data extraction.

 

This is because India spent 90M rupees (AU$1.6M) in April 2025, on a new "black box lab" facility, with their DFDR & CVR Laboratory at the Aircraft Accident Investigation Bureau (AAIB) at Udaan Bhawan, New Delhi.

 

This state-of-the-art facility is obviously their pride and joy, and it was developed and built with assistance from Hindustan Aeronautics Limited (HAL).

 

The IMCA is at pains to state that a decision on where to disassemble and extract the information from the black boxes has not yet been taken, and "The decision regarding the location for decoding the flight recorders will be taken by the AAIB after due assessment of all technical, safety, and security considerations. The Ministry of Civil Aviation urges all stakeholders to refrain from speculation on such sensitive matters, and to allow the investigative process to proceed with the seriousness and professionalism it warrants."

 

https://www.businesstoday.in/latest/corporate/story/ai-171-crash-an-upgrade-for-indias-own-black-box-lab-481055-2025-06-19

[BrendAn]

26 minutes ago, onetrack said:

India's Ministry of Civil Aviation is a bit annoyed with media reports that their ability to read the black boxes is inadequate, and they will be sent to the U.S. or Singapore for data extraction.

 

This is because India spent 90M rupees (AU$1.6M) in April 2025, on a new "black box lab" facility, with their DFDR & CVR Laboratory at the Aircraft Accident Investigation Bureau (AAIB) at Udaan Bhawan, New Delhi.

 

This state-of-the-art facility is obviously their pride and joy, and it was developed and built with assistance from Hindustan Aeronautics Limited (HAL).

 

The IMCA is at pains to state that a decision on where to disassemble and extract the information from the black boxes has not yet been taken, and "The decision regarding the location for decoding the flight recorders will be taken by the AAIB after due assessment of all technical, safety, and security considerations. The Ministry of Civil Aviation urges all stakeholders to refrain from speculation on such sensitive matters, and to allow the investigative process to proceed with the seriousness and professionalism it warrants."

 

https://www.businesstoday.in/latest/corporate/story/ai-171-crash-an-upgrade-for-indias-own-black-box-lab-481055-2025-06-19

Must get a lot for 1.6 m there. Victoria spent over a billion to cancel a contract.

[jackc]

May have helped having a Flight Engineer on crew?  

[Thruster88]

1 hour ago, BrendAn said:

Must get a lot for 1.6 m there. Victoria spent over a billion to cancel a contract.

Laptop, software and a data cable. At aviation prices they might have even got a spare set.

 

[danny_galaga]

4 hours ago, onetrack said:

Danny - India may be quite advanced in some areas, but as far as rubbish generation and failure to collect it, they're still third world.

 

FactHunter - Yes, redundancy in electrics on aircraft would certainly be well addressed, but every LAME with electrical knowledge would quite likely assert that all bets are off once a rodent starts chewing on electrical components.

 

Thruster88 - I'm not so sure about the early warning via error messages. It would only take destruction of wiring to the engine fuel valves to cause double engine failure. A rodent biting into a high voltage aircraft harness would cause a major short circuit instantly. A major short circuit would trip circuit breakers and shut down critical systems at a critical time.

'third world ', is, or was a definition. Look it up and get back to me about whether India is a 'third world' country. 

[onetrack]

O.K. Apparently "Third World", is now an antiquated term, and India is now classed as "First World", due to advances in many parts of the country. But my comment is relevant as regards rubbish.

 

Try looking up, "does India have a rubbish problem", and tell me if their rubbish production and handling is First World.

[onetrack]

Gary Baumgartner ("GaryBPilot") has done some more research on the Dreamliner systems and what he finds is less than reassuring. Possibly the most alarming thing he's found is that the B787-800 has spring-loaded High Pressure Fuel Shut Off Valves ("HPFSOV's"). There are actually two valving systems that can stop fuel feed to the engines, the second system is the Spar Valve.

 

The systems are designed to automatically shut off the fuel to the engines in the event of electrical failure to the fuel metering/supply systems. In Boeings presumption, this is to stop fuel from feeding an engine fire. This makes sense in the basic design.

 

However, there is the possibility that a chaotic electrical event on the B787-800 could shut off the HPFSOV's via the spring activation (and perhaps the Spar Valves as well), and this is something that Gary B is questioning.

According to the authoritative "tdracer" on forums (who I believe is a senior Boeing LAME or engineer), the spring-activated B787-800 fuel valves are solenoid-activated, in both directions - on and off. 

He states that this is to prevent fuel shutoff to the engines in the event of total electrical power loss. That also makes design sense. So according to this information, power is needed to actually shut the fuel supply off.

 

The big question is, what could cause an unintentional solenoid activation of either of the spring-loaded fuel valve systems to the "OFF" position? The possibility of a totally unforeseen method of activation of the fuel valves to the "OFF" position, is a possibility that Boeing engineers may have overlooked.

 

If you watch the video on YouTube, the authoritative and informed comments below the video are interesting.

 

 

 

Edited 21 hours ago by onetrack

[Thruster88]

This is also worth a look if one is not subscribed to this excellent channel. 

 

 

[red750]

Report on TV today that one engine was brand new and the other not due for service till December.