604driver
2025-06-17T17:25:00
permalink Post: 11904491

Low Alt Capture

Quote:

Originally Posted by Magplug

B787 Skipper.... No longer able to sit on my hands!

The joker that published one or other of the fictional accident reports before the dead are even identified needs stringing up by the thumbs.... Well done mods. OK, some of these theories, just bearing in mind the the flight recorder (there is only one FDR + CVR combined) was in the intact section of the undamaged tail and has been with the authorities for almost five days......

- All you guys who are rushing down the TCMA rabbit hole: If it was established that a software error drove both engines to idle without warning, after rotate.... Don't you think the worldwide fleet of B787s would have been grounded by now? Such a glaring failure would be absolutely inescapable on the FDR.

Whatever was wrong with this aircraft was present at rotate, unbeknown to the crew. The fact that no ADs or notices to operators have been issued usually means that the cause is known and the aircraft was serviceable. The statement from a prominent Indian Captain about the skill and tenacity of the crew, right up to the last minute is absolutely laudable. However, the cynic in me says that the way is being paved for some bad news and by that I mean news that will do Air India reputational damage. Expect more management of expectation in the coming days.

I'm still going with
a) Incorrect derate + low Vspeeds or
b) Low altitude capture

a) 🤷‍♂️
b) Wouldn\x92t it capture the Alt rather than descending thru it?

Subjects: CVR DFDR FDR TCMA (All)

3 users liked this post.

604driver
2025-06-17T18:54:00
permalink Post: 11904568

Quote:

Originally Posted by PC767

One would hope, but, whilst there has been confirmation that the EAFRs have been recovered, nothing has been reported about their state or whether they have been downloaded or examined.

If the data is readable there may be a lot of politics and reputation on how that data may be interpreted. Behind the veneer of international cooperation vested interests will be being considered, advocated and agreed.

It, unfortunately, is naive to think that politics will not have a silent presence in agreeing a press release. Boeing and GE are flagship USA companies. Air India is the flagship carrier of India.

Investigations of all types first establish what happened, then how and why, before recommendations and actions. There is a possibility that they know the what, but the how and why incur liability.

Investigators will try to establish a single source or truth. For them, that\x92s an ideal outcome. But due to the nature of investigations, the aim gets derailed as established facts versus possible/potential scenarios based on missing links of the chain are pieced together. But for sure, commercial considerations and liability wont enter into a proper investigation. The task of the investigators is to determine the how and why.

Theres a saying, and it may even have been the title of a book\x85 Lift is a gift but Thrust is a must. In this case, certainly one or both were absent.

For 2 (maybe 3 if it was a training flight) professional people, the day started with waking up, getting ready, saying goodbye to loved ones, who they believed they would see again soon in 2-3 days. Sadly, that won\x92t happen, and it\x92s the job of the investigators to find out why and liability isn\x92t a hindrance to them.

They will look at every piece of evidence and recreate the events. But it will take time.

information worthy of note is:

A) The gear was still down.
B) It would appear (due to some work by amazing members) that the RAT was indeed deployed.

Other observances:

1. Bits flying off the aircraft. (From experience of operating in this area, they like to fly kites, and waste thermals and floats around, notably plastic bags) I have no idea if that la what we see or not.

2. Generally in India, they love using their horns. So whilst you can compare the frequencies of a potential RAT to a motorbike, appreciate there would be a million horns going off too.

3. Some posters have spoken of the \x93startle effect\x94 like they know what they are talking about. The most startling effect of a professional flight deck during an emergency is how calm it is. There aren\x92t hands flying around everywhere. In fact:

V1 > Rotate > Positive Rate > Gear Up > Confirm FD/AP Modes is adjusted to:
V1 > Rotate > Positive Rate > Gear Up > Silence the bell (Or your SOP Variation) FD/AP modes and the PF flies the aircraft.

the next step is to identify the problem, agree on it and then perform the actions. That won\x92t happen below 400\x92.

4. There\x92s no company in the world where Pilots are being fed and watered between V1 and 1000\x92 so spilling drinks on run switches isn\x92t a thing on this departure.

5. Temperature inversion. Yes it\x92s possible and it degrades performance. However, if it\x92s present, it\x92s usually announced on the ATIS. IF other aircraft have reported it.

6. Fuel contamination. Without knowing the systems, yes it\x92s potentially possible, but it would appear no other aircraft have reported being affected by it.

I think, this accident is especially interesting to Professional Aviators and Engineers because I think none of us would ever believe that it could happen. The aircraft is highly automated, the crew have been properly trained and the operation was a regular or possibly training flight.

A query I have is, do later Gen aircraft like the 777/787/747 A330/A350/A380 constantly send Airframe/Engine data home to ops/engineering/oem\x92s. Is it likely the data is out there?

Anyway, I just wanted to post this to reassure the travelling public that Pilots don\x92t try to shut down engines before they raise the gear.

Subjects: Fuel (All) Fuel Contamination Gear Retraction RAT (All) V1

8 users liked this post.

604driver
2025-06-17T20:13:00
permalink Post: 11904614

Quote:

Originally Posted by Chiefttp

767 pilot here, but on the 767 it would capture the altitude, but more importantly, it would freeze the airspeed at whatever speed the alt capture occurred at. So the thrust levers would retard to maintain the much slower speed at the point of capture. This could be a possible scenario, especially if the crew was slow to realize what happened.

Ooh really? As opposed to an FMS speed. That\x92s an interesting fact. So does that mean the A/T could potentially capture a speed below Min speed for the config?

No idea about the 787\x85 but assume the HUD and PFD/ND Screen symbology keeps you aware of T/L position with regards to commanded speed and resultant energy state?

Apologies no bias as to this accident, just love learning how other manufacturers tackle the same work flows.

Subjects: None

2 users liked this post.

604driver
2025-06-19T08:50:00
permalink Post: 11905843

Quote:

Originally Posted by Shep69

The autopilot would not have been in and the pilot would have been hand flying maintaining the takeoff attitude. The flight director might have commanded a level off which obviously would not have been followed.

Minimum autopilot engagement altitude is 200\x92 for the 78 (from others on the forum). It\x92s 400\x92 AGL on the 777.

My interest is in how the auto throttles would have behaved in such a situation\x97where VNAV would not be engaged yet and the automatics gone into SPD/ALT. ; would they have pulled off thrust assuming a level off and then come back in to maintain bug speed (perhaps confusing the crew in the process ?).

Dont know the 78 but presumably the AT commands HOLD at 60-80 kts and stays there until once above 400\x92 either a config change or flight guidance mode selection. If the FD commanded a level off below 400\x92 it\x92s been suggested that the AT would transition to SPD mode.

This is a daft question probably, but if the automation commanded a level off below 400\x92 and the AT transitioned to SPD\x85 would the logic have a brain fart and revert back to HOLD? I\x92m guessing not to be honest. I wonder if people have managed to try this in the SIM.

Not saying at all that is what happened here. Just interested in the logic.

Subjects: VNAV

604driver
2025-06-20T18:28:00
permalink Post: 11907185

Data Recorders

1. Had to re-check this as the course I did a long time ago\x85 was a long time ago.

Recorders are stressed to 3,500 G\x92s.

They are Data Recorders\x85 not a plug me in, put the popcorn on, lay back and watch the accident unfold in IMAX quality.

Once (If) the data is recovered, it has to be calibrated, then interpreted.

The data is digital and hexadecimal. It needs to be interpreted, verified, cross checked and collated to build a picture.

In an undamaged state, data can be extracted within hours. Then calibrated and contextualised.

In a damaged unit\x85 it\x92s significantly longer. The delay that has been put forth, is entirely normal.

2. There have been several references of \x93fire walling\x94 the thrust levers or \x93slamming the thrust levers\x94 to get instant power\x85 go check this in the sim\x85 Slamming the T/L forward\x85 do not give you power any quicker than pressing the G/A button. HOWEVER\x85 its does give 1 source of confirmation that max thrust has been commanded. The other is to always say,

Go Around > Check Thrust (or \x93xxx\x94 check thrust\x85 for stall recovery etc etc) and wait there before thrust recovery occurs and that confirmation is received, before progressing with.. Flaps x, positive rate\x85 yada yada yada.

Personally I\x92m learning a lot from this thread. What I\x92m learning I\x92ll keep to myself.

A previous poster, apologies I can\x92t give you credit as I didn\x92t keep your handle, said something like\x85 it appears, the most likely outcome is as a result of the least likely scenario

Peace to all

Subjects: None

5 users liked this post.

604driver
2025-06-20T19:14:00
permalink Post: 11907224

Quote:

Originally Posted by nachtmusak

I am specifically asking about the case without a malfunction because my understanding is that the autothrottle explicitly does not affect thrust between passing 80 knots on the runway and passing 400 ft AGL.

Neither does (or should?) any autopilot mode (except LNAV? at 50 feet?) be active under 400 feet. Armed yes but not actually engaged.

So how would either of these things have any effect on an aircraft that's just lifting off unless they're faulty? Everything I can turn up seems very clear that the autothrottle, VNAV, etc only engage at 400 feet AGL on departure. In fact, both altitude capture incidents I've been able to turn up were only triggered when the autopilot was engaged. Why would any pilot be engaging the autopilot bare seconds after lift-off?

There are some cases, type specific for example, where the conditions could preclude A/T actually being engaged for departure.

No idea of 787

There are other cases where maybe A/T is U/S

Not saying any of those things were relevant here. Just answering your question.

Subjects: VNAV

604driver 2025-06-17T17:25:00 permalink Post: 11904491	Low Alt Capture Quote: Originally Posted by Magplug B787 Skipper.... No longer able to sit on my hands! The joker that published one or other of the fictional accident reports before the dead are even identified needs stringing up by the thumbs.... Well done mods. OK, some of these theories, just bearing in mind the the flight recorder (there is only one FDR + CVR combined) was in the intact section of the undamaged tail and has been with the authorities for almost five days...... - All you guys who are rushing down the TCMA rabbit hole: If it was established that a software error drove both engines to idle without warning, after rotate.... Don't you think the worldwide fleet of B787s would have been grounded by now? Such a glaring failure would be absolutely inescapable on the FDR. Whatever was wrong with this aircraft was present at rotate, unbeknown to the crew. The fact that no ADs or notices to operators have been issued usually means that the cause is known and the aircraft was serviceable. The statement from a prominent Indian Captain about the skill and tenacity of the crew, right up to the last minute is absolutely laudable. However, the cynic in me says that the way is being paved for some bad news and by that I mean news that will do Air India reputational damage. Expect more management of expectation in the coming days. I'm still going with a) Incorrect derate + low Vspeeds or b) Low altitude capture a) 🤷‍♂️ b) Wouldn\x92t it capture the Alt rather than descending thru it? Subjects: CVR DFDR FDR TCMA (All) 3 users liked this post.
604driver 2025-06-17T18:54:00 permalink Post: 11904568	Quote: Originally Posted by PC767 One would hope, but, whilst there has been confirmation that the EAFRs have been recovered, nothing has been reported about their state or whether they have been downloaded or examined. If the data is readable there may be a lot of politics and reputation on how that data may be interpreted. Behind the veneer of international cooperation vested interests will be being considered, advocated and agreed. It, unfortunately, is naive to think that politics will not have a silent presence in agreeing a press release. Boeing and GE are flagship USA companies. Air India is the flagship carrier of India. Investigations of all types first establish what happened, then how and why, before recommendations and actions. There is a possibility that they know the what, but the how and why incur liability. Investigators will try to establish a single source or truth. For them, that\x92s an ideal outcome. But due to the nature of investigations, the aim gets derailed as established facts versus possible/potential scenarios based on missing links of the chain are pieced together. But for sure, commercial considerations and liability wont enter into a proper investigation. The task of the investigators is to determine the how and why. Theres a saying, and it may even have been the title of a book\x85 Lift is a gift but Thrust is a must. In this case, certainly one or both were absent. For 2 (maybe 3 if it was a training flight) professional people, the day started with waking up, getting ready, saying goodbye to loved ones, who they believed they would see again soon in 2-3 days. Sadly, that won\x92t happen, and it\x92s the job of the investigators to find out why and liability isn\x92t a hindrance to them. They will look at every piece of evidence and recreate the events. But it will take time. information worthy of note is: A) The gear was still down. B) It would appear (due to some work by amazing members) that the RAT was indeed deployed. Other observances: 1. Bits flying off the aircraft. (From experience of operating in this area, they like to fly kites, and waste thermals and floats around, notably plastic bags) I have no idea if that la what we see or not. 2. Generally in India, they love using their horns. So whilst you can compare the frequencies of a potential RAT to a motorbike, appreciate there would be a million horns going off too. 3. Some posters have spoken of the \x93startle effect\x94 like they know what they are talking about. The most startling effect of a professional flight deck during an emergency is how calm it is. There aren\x92t hands flying around everywhere. In fact: V1 > Rotate > Positive Rate > Gear Up > Confirm FD/AP Modes is adjusted to: V1 > Rotate > Positive Rate > Gear Up > Silence the bell (Or your SOP Variation) FD/AP modes and the PF flies the aircraft. the next step is to identify the problem, agree on it and then perform the actions. That won\x92t happen below 400\x92. 4. There\x92s no company in the world where Pilots are being fed and watered between V1 and 1000\x92 so spilling drinks on run switches isn\x92t a thing on this departure. 5. Temperature inversion. Yes it\x92s possible and it degrades performance. However, if it\x92s present, it\x92s usually announced on the ATIS. IF other aircraft have reported it. 6. Fuel contamination. Without knowing the systems, yes it\x92s potentially possible, but it would appear no other aircraft have reported being affected by it. I think, this accident is especially interesting to Professional Aviators and Engineers because I think none of us would ever believe that it could happen. The aircraft is highly automated, the crew have been properly trained and the operation was a regular or possibly training flight. A query I have is, do later Gen aircraft like the 777/787/747 A330/A350/A380 constantly send Airframe/Engine data home to ops/engineering/oem\x92s. Is it likely the data is out there? Anyway, I just wanted to post this to reassure the travelling public that Pilots don\x92t try to shut down engines before they raise the gear. Subjects: Fuel (All) Fuel Contamination Gear Retraction RAT (All) V1 8 users liked this post.
604driver 2025-06-17T20:13:00 permalink Post: 11904614	Quote: Originally Posted by Chiefttp 767 pilot here, but on the 767 it would capture the altitude, but more importantly, it would freeze the airspeed at whatever speed the alt capture occurred at. So the thrust levers would retard to maintain the much slower speed at the point of capture. This could be a possible scenario, especially if the crew was slow to realize what happened. Ooh really? As opposed to an FMS speed. That\x92s an interesting fact. So does that mean the A/T could potentially capture a speed below Min speed for the config? No idea about the 787\x85 but assume the HUD and PFD/ND Screen symbology keeps you aware of T/L position with regards to commanded speed and resultant energy state? Apologies no bias as to this accident, just love learning how other manufacturers tackle the same work flows. Subjects: None 2 users liked this post.
604driver 2025-06-19T08:50:00 permalink Post: 11905843	Quote: Originally Posted by Shep69 The autopilot would not have been in and the pilot would have been hand flying maintaining the takeoff attitude. The flight director might have commanded a level off which obviously would not have been followed. Minimum autopilot engagement altitude is 200\x92 for the 78 (from others on the forum). It\x92s 400\x92 AGL on the 777. My interest is in how the auto throttles would have behaved in such a situation\x97where VNAV would not be engaged yet and the automatics gone into SPD/ALT. ; would they have pulled off thrust assuming a level off and then come back in to maintain bug speed (perhaps confusing the crew in the process ?). Dont know the 78 but presumably the AT commands HOLD at 60-80 kts and stays there until once above 400\x92 either a config change or flight guidance mode selection. If the FD commanded a level off below 400\x92 it\x92s been suggested that the AT would transition to SPD mode. This is a daft question probably, but if the automation commanded a level off below 400\x92 and the AT transitioned to SPD\x85 would the logic have a brain fart and revert back to HOLD? I\x92m guessing not to be honest. I wonder if people have managed to try this in the SIM. Not saying at all that is what happened here. Just interested in the logic. Subjects: VNAV
604driver 2025-06-20T18:28:00 permalink Post: 11907185	Data Recorders 1. Had to re-check this as the course I did a long time ago\x85 was a long time ago. Recorders are stressed to 3,500 G\x92s. They are Data Recorders\x85 not a plug me in, put the popcorn on, lay back and watch the accident unfold in IMAX quality. Once (If) the data is recovered, it has to be calibrated, then interpreted. The data is digital and hexadecimal. It needs to be interpreted, verified, cross checked and collated to build a picture. In an undamaged state, data can be extracted within hours. Then calibrated and contextualised. In a damaged unit\x85 it\x92s significantly longer. The delay that has been put forth, is entirely normal. 2. There have been several references of \x93fire walling\x94 the thrust levers or \x93slamming the thrust levers\x94 to get instant power\x85 go check this in the sim\x85 Slamming the T/L forward\x85 do not give you power any quicker than pressing the G/A button. HOWEVER\x85 its does give 1 source of confirmation that max thrust has been commanded. The other is to always say, Go Around > Check Thrust (or \x93xxx\x94 check thrust\x85 for stall recovery etc etc) and wait there before thrust recovery occurs and that confirmation is received, before progressing with.. Flaps x, positive rate\x85 yada yada yada. Personally I\x92m learning a lot from this thread. What I\x92m learning I\x92ll keep to myself. A previous poster, apologies I can\x92t give you credit as I didn\x92t keep your handle, said something like\x85 it appears, the most likely outcome is as a result of the least likely scenario Peace to all Subjects: None 5 users liked this post.
604driver 2025-06-20T19:14:00 permalink Post: 11907224	Quote: Originally Posted by nachtmusak I am specifically asking about the case without a malfunction because my understanding is that the autothrottle explicitly does not affect thrust between passing 80 knots on the runway and passing 400 ft AGL. Neither does (or should?) any autopilot mode (except LNAV? at 50 feet?) be active under 400 feet. Armed yes but not actually engaged. So how would either of these things have any effect on an aircraft that's just lifting off unless they're faulty? Everything I can turn up seems very clear that the autothrottle, VNAV, etc only engage at 400 feet AGL on departure. In fact, both altitude capture incidents I've been able to turn up were only triggered when the autopilot was engaged. Why would any pilot be engaging the autopilot bare seconds after lift-off? There are some cases, type specific for example, where the conditions could preclude A/T actually being engaged for departure. No idea of 787 There are other cases where maybe A/T is U/S Not saying any of those things were relevant here. Just answering your question. Subjects: VNAV

Posts by user "604driver" [Posts: 6 Total up-votes: 18 Pages: 1]