2025-06-12T11:55:00
permalink Post: 11899120
Sadly, the local police have just said that there appear to be no survivors from the aircraft. RIP.
Subjects: None
2025-06-13T09:08:00
permalink Post: 11900219
Quoting the Telegraph UK:
The Indian government is considering grounding Air India’s Boeing 787 fleet after one of its planes crashed, killing more than 240 people.
The country’s Ministry of Civil Aviation is mulling grounding all Boeing 787-8 Dreamliners as a precautionary measure while a safety review takes place, sources told Indian broadcaster NDTV.
The country’s Ministry of Civil Aviation is mulling grounding all Boeing 787-8 Dreamliners as a precautionary measure while a safety review takes place, sources told Indian broadcaster NDTV.
Subjects: None
2025-06-13T10:42:00
permalink Post: 11900329
Reading the various reports about electrical problems on the prior and this flight, such as flickering lights reminded me of the BMI A321 incident discussed here 15 years ago:
https://www.pprune.org/archive/index.php/t-433616.html
A faulty generator caused all sorts of problems with control of the aircraft. It is a reminder that complete electrical failure is not the only failure mode. Shutting down the faulty generator on that aircraft recovered the situation, but they had time and altitude on their side.
https://www.pprune.org/archive/index.php/t-433616.html
A faulty generator caused all sorts of problems with control of the aircraft. It is a reminder that complete electrical failure is not the only failure mode. Shutting down the faulty generator on that aircraft recovered the situation, but they had time and altitude on their side.
Subjects: Electrical Failure Generators/Alternators
2025-06-13T10:56:00
permalink Post: 11900345
A Google search for Dreamliner cabin lighting brings up some of the marketing from airlines when the aircraft came into service. There are a multitude of colours shown. I recall debate at the time whether it was cool or tacky.
Subjects: None
2025-06-14T17:15:00
permalink Post: 11901671
AAIB (UK) Update: Air India flight AI171
A team of four investigators from the UK Air Accidents Investigation Branch (AAIB) has arrived in India. They have expertise in aircraft operations, engineering and recorded data. Their role is to provide additional support and expertise to the safety investigation being led by India\x92s Aircraft Accident Investigation Bureau.
The UK AAIB has \x91Expert\x92 status in the Indian safety investigation. In accordance with international protocols, release of information on the investigation rests solely with the Indian authorities.
The UK AAIB has \x91Expert\x92 status in the Indian safety investigation. In accordance with international protocols, release of information on the investigation rests solely with the Indian authorities.
Subjects: AAIB (All) AAIB (UK) AI171
2025-06-16T05:52:00
permalink Post: 11903115
On the 747, Weight on Wheels (WoW) depends on prox sensors on the landing gear (i.e. gear compression). I don't know how that's done on the 787.
The reason we used both Radio Alt and WoW is that both can give erroneous indications on certain conditions - RA can be 'fooled' by dense rain or even really dense fog (the signals bounce off the water and falsely indicate on-ground), the prox sensor system can subject to HIRF/Lightning interference.
TCMA acts quickly, but it does require some persistence, so an input glitch won't activate it (mainly N1, which is measured every 15 milliseconds).
What sort of 'confirmation' do you have in mind - the regulator mandate that resulted in TCMA basically says we can't take credit for the flight crew.
The reason we used both Radio Alt and WoW is that both can give erroneous indications on certain conditions - RA can be 'fooled' by dense rain or even really dense fog (the signals bounce off the water and falsely indicate on-ground), the prox sensor system can subject to HIRF/Lightning interference.
TCMA acts quickly, but it does require some persistence, so an input glitch won't activate it (mainly N1, which is measured every 15 milliseconds).
What sort of 'confirmation' do you have in mind - the regulator mandate that resulted in TCMA basically says we can't take credit for the flight crew.
Subjects: Gear Retraction TCMA (All) Weight on Wheels
2025-06-19T10:13:00
permalink Post: 11905888
Subjects: None
1 user liked this post.
2025-06-19T11:01:00
permalink Post: 11905926
I\x92ve had a look at the Honeywell spec sheet for TL type switches. They are a common type with many available configurations and are essentially a normal looking snap action switch. The locking feature is an add-on which can be specified. I have to say that from the diagrams, the locking mechanism doesn\x92t look that robust and I\x92d guess that it is subject to wear which was probably the basis of the SAIB. Given that this is a mechanical locking device seeing frequent use possibly with less than full mechanical sympathy it is possible to see how wear could occur. This does beg the question of how whether a check on the mechanism has made it into maintenance routines. ( Note - the locking mechanism appears to be the same for all TL switch types) . Those familiar with the switches - what do you think?
Subjects: Condolences
4 users liked this post.
2025-06-19T11:47:00
permalink Post: 11905963
Subjects: None
3 users liked this post.
2025-06-19T13:08:00
permalink Post: 11906013
Yes, seems like they also come in a on-off-on version, but the thing is what could happen when the mechanical function is worn, which is a thing with switches used over time in real world scenarios.
It seems the design, function and placement of these switches might have been \x93grandfathered\x94 over several generations of cockpit design.
It seems the design, function and placement of these switches might have been \x93grandfathered\x94 over several generations of cockpit design.
Subjects: None
2025-06-19T14:36:00
permalink Post: 11906073
I have read most of the thread (old and new). As a lawyer working in forensic investigations, I am constantly involved in problem-solving. My field of work also includes complex investigations related to insolvencies, which almost always require an analysis of the causes behind a specific, established outcome. In doing so, I naturally also have to deal with probabilities. However, it often turns out that the most likely or plausible explanation does not reflect what actually happened.
Many of the considerations I\x92ve read fail because the simultaneous failure of both engines is extremely unlikely, leading to a constant search for higher-order causes. It was suggested that an incorrect altitude setting led to an early thrust reduction. However, this would not explain the deployment of the RAT (Ram Air Turbine), especially since the thrust could have been readjusted. FADEC and TCAM are highly redundant systems, and TCAM failure is unlikely due to WOW (Weight on Wheels) logic, making a simultaneous engine failure after VR equally improbable.
With that said, and with regard to my question concerning the AD that relates to the fuel control switches (FCS), my thought\x97and it was nothing more than that\x97was that their activation becomes more probable if it can occur accidentally. That\x92s how I came across SAIB: NM-18-33.
Another user then brought up an iPhone. That notion would, of course, be dramatic\x97but how unlikely is it really that after approximately 10,000 actuations between December 2013 and June 2025, the two FCS no longer lock perfectly? Considering all of this, I find it quite conceivable that the A/T slightly reduced thrust in the first seconds after VR (e.g., if an incorrect target altitude had been entered) and that an object lying between the thrust levers and the FCS could have pushed the FCS into the \x93Off\x94 position. Due to the buttons on top of the switches, which provide some resistance, it\x92s even possible that the object both pulled and pushed them.
But all of this is speculation. The investigation report will bring clarity.
Even if my theory is not confirmed, I still believe that the positioning and mechanism of the FCS are suboptimal. Switches of such critical importance should be better protected, and movements in the area in front of the switches (like reducing thrust) should not follow the same direction as shutting off the fuel supply. A different switching direction alone would provide more safety\x97especially considering that the FCS are protected laterally by metal plates.
Many of the considerations I\x92ve read fail because the simultaneous failure of both engines is extremely unlikely, leading to a constant search for higher-order causes. It was suggested that an incorrect altitude setting led to an early thrust reduction. However, this would not explain the deployment of the RAT (Ram Air Turbine), especially since the thrust could have been readjusted. FADEC and TCAM are highly redundant systems, and TCAM failure is unlikely due to WOW (Weight on Wheels) logic, making a simultaneous engine failure after VR equally improbable.
With that said, and with regard to my question concerning the AD that relates to the fuel control switches (FCS), my thought\x97and it was nothing more than that\x97was that their activation becomes more probable if it can occur accidentally. That\x92s how I came across SAIB: NM-18-33.
Another user then brought up an iPhone. That notion would, of course, be dramatic\x97but how unlikely is it really that after approximately 10,000 actuations between December 2013 and June 2025, the two FCS no longer lock perfectly? Considering all of this, I find it quite conceivable that the A/T slightly reduced thrust in the first seconds after VR (e.g., if an incorrect target altitude had been entered) and that an object lying between the thrust levers and the FCS could have pushed the FCS into the \x93Off\x94 position. Due to the buttons on top of the switches, which provide some resistance, it\x92s even possible that the object both pulled and pushed them.
But all of this is speculation. The investigation report will bring clarity.
Even if my theory is not confirmed, I still believe that the positioning and mechanism of the FCS are suboptimal. Switches of such critical importance should be better protected, and movements in the area in front of the switches (like reducing thrust) should not follow the same direction as shutting off the fuel supply. A different switching direction alone would provide more safety\x97especially considering that the FCS are protected laterally by metal plates.
Subjects: Air Worthiness Directives Engine Failure (All) FADEC Fuel (All) Fuel Cutoff Fuel Pumps RAT (All) RAT (Deployment) Weight on Wheels
6 users liked this post.