Posts by user "Sailvi767" [Posts: 42 Total up-votes: 102 Pages: 3]

Sailvi767
2025-06-18T02:49:00
permalink
Post: 11904851
Originally Posted by Capn Bloggs
Yes, while there were other complications in play, this accident was caused by a single- throttle rollback after takeoff that wasn't detected by the crew:

https://en.wikipedia.org/wiki/TAROM_Flight_371

To my way of thinking, if you are in the habit of having your hand on the TLs, you're more likely to push them up when needed.
I won\x92t debate if having hands on or off the trust levers is best practice. I will however point out that many airlines train to remove hands from the throttles at V1. This is supposed to reduce the chances of an inappropriate high speed abort.

Subjects: V1

1 user liked this post.

Sailvi767
2025-06-18T15:00:00
permalink
Post: 11905313
Originally Posted by steamchicken
There has been a lot of discussion of the possibility that the crew shut down the wrong engine or misidentified some other problem as an engine failure, usually followed by an assertion that nobody would touch the engines before x feet. PPRuNe's own survey, at the top of this very subforum, found a really high base rate of wrong engine incidents:
  • 31 per cent of the PPRuNe Population reported either having a wrong-engine incident or a close call
  • 61 per cent reported witnessing one
This might be biased upwards by people who have had the experience being more likely to engage with a thread about it and to respond to the survey, although on the other hand the difference between self-reported errors and witnessed ones shows there's also some bias to under-reporting. In the light of those observations you should surely have quite a strong prior that an erroneous engine shutdown is possible.

Also, on the point about sitting on your hands to 400/1000 feet AAL, someone who has already deviated from a standard operating procedure is more likely to go on to make another mistake; that is why the procedure existed in the first place.

As a memo item, here are the survey results:

Q1. Have you ever shut off the wrong engine in the sim?
Yes: 5.4% +0.9%
No: 94.6% -0.9%

Q2. Have you ever ALMOST shut off the wrong engine in the sim?
Yes: 26% -1.0%
No: 74% +1.0%

Q3. Have you ever witnessed a colleague shut off the wrong engine in the sim?
Yes: 16% +1.0%
No: 84% -1.0%

Q4. Have you ever witnessed a colleague ALMOST shut off the wrong engine in the sim?
Yes: 45% +2.0%
No: 55% -2.0%

Link to original post

Senior Pilot
A better question would related to this accident would be have you ever shut down the wrong engine below 200 feet AGL in the sim. I strongly suspect the answer would be zero percent.

Subjects: Engine Failure (All)  Engine Shutdown  Wrong Engine

2 users liked this post.

Sailvi767
2025-06-18T22:04:00
permalink
Post: 11905578
Originally Posted by Mechta
Yes the centre tank is used first, if it has been filled in the first place, however if the previous flights were sufficiently short to not need the centre tank fuel, it wouldn't have been filled for those flights, would it?
Correct. If the flights involved needed less than 128,000 lbs of fuel the center tank would not be used. There is a scavenge system to insure the center tank remains empty when burning from the wing tanks. On the flight in question 128,000 lbs of fuel would in fact likely be close to the fuel required. The center tank might have been empty or contained a small amount of fuel. It\x92s quite possible the aircraft could have been transitioning from center tank to wing tank fuel at liftoff. With the design of the fuel system I can\x92t really see how that could be significant but I am sure it will be looked at in the investigation.

Subjects: Centre Tank

1 user liked this post.

Sailvi767
2025-06-18T22:30:00
permalink
Post: 11905595
Originally Posted by EDML
Block fuel should have been around 50t. Each wing holds 16.9t. That means at least around 16t would have been in the center fuel tank.

Sorry for the metric values ;-)
Never do math in public. You are correct. The center tank should have had a significant amount of fuel at takeoff. Probably at least 40,000 lbs.

Subjects: Centre Tank  EDML

1 user liked this post.

Sailvi767
2025-06-19T11:08:00
permalink
Post: 11905928
Originally Posted by Magplug
I have to agree with you PBL . It is amazing that people are still arguing about the height the aircraft reached during the first 11s of the flight. It is almost measurable to the metre from the aircraft wingspan on the video. Do not mistake the power required to reach Vr within in the TORA with the power required to maintain a stable climb at V2 to V2+10 in the second and third segments. They are very different numbers, that's why Perf A is one of the dark arts of aviation! It is quite probable that this aircraft rotated below a suitable Vr speed for the weight and ambient conditions and was unable to establish a stable climb due lack of applied power. Big engines take time to spool up, your immediate future depends on how late you recognise the situation and go for TOGA.

But you ask..... How can an aircraft possibly get airborne with a stalled wing? Look at Air France 7775 . At rotate the wing was already stalled (albeit for different reasons) but the airborne profile of the aircraft was rather similar to Air India.
The rotation in the video appears normal and tail clearance is normal as well. That suggests VR was correct as well as the flap setting.

Subjects: Flap Setting  Flaps (All)  TOGA  V2

3 users liked this post.

Sailvi767
2025-06-19T18:28:00
permalink
Post: 11906250
Originally Posted by CloudChasing
Software Engineer here. IMO software glitches are more likely than mechanical failures and pilot error, and I would say increasingly more so, particularly with Boeings. I have good reasons, experience and expertise for saying this that I\x92m not going to get into here because it\x92s too long winded and will no doubt upset some people who will mistake facts for rule and let it hurt their feelings.

In 2019 I think it was, an ANA 787 had a TMCA dual engine shutdown just after landing. There was also a bug that shut down all AC power on 787s powered on for 248+ days (integer overflow causing GCU failsafe) that was supposed to be remedied on 2019. Can\x92t find any information confirming that it was implemented on all 787s. These are just two examples of software bugs. There are placed of others, and it\x92s highly likely there are ones we don\x92t know about, either in the original software or in the updates.
The bug shutting all power off after 248 continuous powered days would not have shut down running engines if my understanding is correct. The FADEC\x92s are self powered and would continue to operate as discussed in other posts.

Subjects: Dual Engine Failure  Engine Failure (All)  Engine Shutdown

3 users liked this post.

Sailvi767
2025-06-20T13:30:00
permalink
Post: 11906974
Originally Posted by sSquares
Shutting down the wrong engine is not extremely rare:
  1. GoAir320 at Delhi
  2. Transasia AT72 at Taipei
  3. Alitalia A332 at Seoul
  4. SA Airlink JS41 at Durban

Not saying it happened here!
Shutting down the wrong engine below 400 AGL is extremely rare. So rare in fact that I believe it has not happened in a jet transport class aircraft.

Subjects: Engine Failure (All)  Wrong Engine

1 user liked this post.

Sailvi767
2025-06-20T13:38:00
permalink
Post: 11906979
Originally Posted by BraceBrace
During a flameout it takes a while before the fan has slowed down sufficiently. As long as it rotates, thrust is generated.

With full reverse thrust you know that when de-selecting reverser from idle reverse, you have to give the engines plenty of time to slow down otherwise you would get the little "kick in the back" as during deceleration you would generate instant forward thrust when the reversers are stowed.
The fan never stops rotating in a normal engine loss. Having been through a catastrophic engine failure in a 767 I can tell you that trust stops almost instantly. Certainly no more than 2 seconds. It also needs to be understood that thrust is not linear to engine speed in a jet. Very little thrust is generated below 70% RPM and thrust increases rapidly above 85%. The fan simple becomes a big source of drag almost immediately if the turbine section shuts down or fails.

Subjects: Engine Failure (All)

13 users liked this post.

Sailvi767
2025-06-20T13:41:00
permalink
Post: 11906982
Originally Posted by Musician
For comparison, the ADS-B data show the ground speed dropping off from 184 knots to 172 knots over 4.3 seconds as the aircraft climbs.
You would expect that decrease given the winds reported that day. The winds at 100 feet AGL are generally higher than at ground level.

Subjects: ADSB

Sailvi767
2025-06-21T12:31:00
permalink
Post: 11907707
Originally Posted by FullWings
It’s a possibility (as is virtually anything that doesn’t break the laws of physics) but all the training, practicing and checking would have been to emphasise SOPs, which are to leave all the engine controls where they are until you have done a proper interactive diagnosis at a safe height with the flightpath assured.

Where the meme has come from that jet pilots have to shut down engines as quickly as possible I don’t know but it is incorrect. If you left a failed engine without securing it for 5 minutes, little to no harm would come of it. Even if it was on fire (which is not necessarily flames, just higher than normal temperatures inside the nacelle) they are certified to be in this condition for some considerable time before it becomes a problem. Yes, I think the phrase “without undue delay” could be used for a fire indication but that’s a minimum of 400’AGL in Boeings and does not absolve you of all the cross-checking and CRM that should happen with an engine shutdown. This is practiced/checked at the least every 6 months in EASA land and any attempt to rush a shutdown at low level would lead to a debrief and more training/checking.

To put it this way, control of the aeroplane and lateral/vertical navigation is far more important than doing stuff with a failed power plant. Something like an ET should be absolutely prioritised over engine drills.
My airline emphasized no crew action for engine failure or fire until 1000 feet. At 400 feet we could only declare an emergency, request an alternate departure if needed and start the APU. It’s far more important to fly the aircraft, get it properly trimmed and insure the proper engine out ground track is being flown. Only at 1000 feet would we begin the engine fire/failure checklist. Normally even that would come after the aircraft was cleaned up and stabilized. Best flying advice I ever got was in a severe emergency the first thing you should do is wind the clock!

Subjects: APU  Engine Failure (All)  Engine Shutdown

14 users liked this post.

Sailvi767
2025-06-21T14:10:00
permalink
Post: 11907785
Originally Posted by CloudChasing
according to multiple Indian media sources, refuelling at AMD took longer than usual as the plane was fully refuelled, despite only needing 53% for the journey
Fully fueled with the reported passenger load the 787-8 would have exceeded max takeoff weight. In fact the -8 would only have about 15,000 lbs of available payload with full fuel at max structural weight. In addition given the temperatures reported it’s likely the climb weight limit would be even less than the structural limit resulting in zero payload. If somehow the departure could be accomplished they would be well in excess of max landing weight at Gatwick.

Subjects: None

5 users liked this post.

Sailvi767
2025-06-21T20:23:00
permalink
Post: 11908027
Originally Posted by nachtmusak
Do you happen to have a link to this briefing? The search results for this accident are so terribly messed up with speculation and rumours that I can't quite find it.

Asking because if there is official confirmation that the captain was the pilot flying, as well as official confirmation that he was the one who made the mayday call, is that not another clue pointing towards total loss of AC power (as opposed to thrust merely being rolled back to idle)? In the sense that only the captain's radio is on the battery bus so if he was the one making the call instead of the first officer who should have been monitoring, it could be because he was the only one in the cockpit who could.
On other Boeing aircraft that are down to emergency power only the number 1 radio functions. It however functions just fine from any crew station. The radio\x92s are not isolated to a specific user. I would be very surprised if the 787 was different.

Subjects: Mayday

2 users liked this post.

Sailvi767
2025-06-26T21:52:00
permalink
Post: 11911524
Originally Posted by Kraftstoffvondesibel
Not quite sure if this thread is open again or not.

I wanted to bring something up.
Maybe I am out of touch, but the way we have talked about this accident, we have talked about it like it were doomed to be an unsurviveable high energy crash inferno.
I, at least, have been guilty of having this picture in my mind.
Wasn't this a, relatively speaking, a low energy impact scenario, comparable to Air France 269, SAS 751, BA038, or a number of other accidents including things like the hudson river event, which would have been somewhat surviveable except the impact with the buildings?

There looks to be more open areas in close proximity to the accident site that are as big, 150-250 meters, or larger than what either of those others had available or at least used.
There have been comments of the docile trajectory of the aircraft being a sign of pilots giving up, and letting automation take over of sorts, but in reality, could it be they just did exactly the same as the crew on BA038 or SAS 751? Except the lack of luck?

In connection with this, why would the recorders be so damaged it has taken them weeks to access them. It seems that kind of impact should be well within the envolope for those designs.

If out of bounds or order, please delete.
The aircraft from the time they lost thrust to impact was probably less than 20 seconds. At a low energy state the best the crew could do was try and break the rate of descent. There was no opportunity to try and maneuver to the best landing site. As far as the FDR’s it appears they functioned exactly as designed. The intense fire would badly damage the FDR boxes and associated electronics. The chip which is the component that is heavily protected so far seems just fine.

Subjects: FDR

1 user liked this post.

Sailvi767
2025-06-28T12:29:00
permalink
Post: 11912472
I suspect both recorders will contain the same data. Given the radio transmission after the loss of thrust the aircraft still had at least the emergency electrical bus powered. This should have kept both recorders online. It is however possible given the 10 minute battery backup that Boeing chose to put the the recorders on another bus but that’s not the norm.

Subjects: None

Sailvi767
2025-06-29T14:02:00
permalink
Post: 11913050
I see nothing in the video’s to suggest the aircraft was out of control. It was gliding almost exactly as you can expect from an event starting with the gear down and flaps at 5. As the aircraft nears the ground it appears there is a bit of flare to break the rate of descent. That is exactly what you would expect the pilots to do and their only course of action with a dual engine failure at low altitude.

Subjects: Dual Engine Failure  Engine Failure (All)  Gear Retraction

4 users liked this post.

Sailvi767
2025-06-30T00:40:00
permalink
Post: 11913309
Originally Posted by Tailspin Turtle
An admittedly approximate assessment of the airplane's lift-over-drag capability, considering other conditions (head wind, ground effect, actual airspeed vs that required to maximize L/D, etc.) suggests that the engines were providing some thrust in order for it to get as far as it did. Note that simple calculations based on conversion of energy, e.g. velocity and height, to distance are even more approximate in this scenario.
I would disagree with this. Given the airspeed at 174 knots and a peak altitude of about 175 feet the aircraft had some energy for the pilots to work with. Stall speed was likely around 120 knots so they had 55 knots of airspeed and 175 feet of altitude to convert to distance.

Subjects: Lift/Drag Ratio

Sailvi767
2025-06-30T01:49:00
permalink
Post: 11913322
Originally Posted by za9ra22
OK, from my standpoint as a curious observer, what would their options be? They don't have engines to provide thrust, they don't have altitude to lower the nose and gain speed, and they don't have the speed to pull the nose up and extend the glide? All while trying to troubleshoot the same problem we've collectively taken 2 weeks to not understand. What would you do?
Rxactly what they did. Fly the aircraft to the last moment and break the rate of descent. Unfortunately they hit a large building. My post however was referring to the distance the aircraft glided after the power loss. The distance seems reasonable with the energy state of the aircraft.

Subjects: None

1 user liked this post.

Sailvi767
2025-06-30T18:47:00
permalink
Post: 11913841
Originally Posted by GroundedSpanner
Thanks but I want to separate the RAT issue from the engines/thrust issue.
Its possible that the RAT was deployed for other reasons, prior to the engines losing thrust. So, leaving the RAT out of the equation for a bit, do we think there is a sound of engines TRYING to run?
It would go against every aspect of training for a professional crew to deploy the rat below 400 feet. Further if you put 100 crewmembers in a simulator on takeoff and said deploy the rat manually I would bet not a single crew member could find the rat deploy switch and activate it in under 5 seconds and maybe 2 or 3 in 10 seconds.

Subjects: RAT (All)  RAT (Deployment)

4 users liked this post.

Sailvi767
2025-06-30T18:57:00
permalink
Post: 11913849
Originally Posted by Abbas Ibn Firnas
I found descriptions on the systems of the 787 were easily discovered online, and while I have no hands-on experience of aircraft related matters, I do have experience in wider electrical theory and maintenance.

THRUST Asymmetry PROTECTION.
"For an engine-out condition, Thrust Asymmetry Protection (TAP) reduces thrust on the operating engine to ensure there is sufficient rudder for directional control. TAP reduces thrust when the airspeed decreases below approximately V2 on a takeoff or below approximately VREF on a go-around. Once speed is increased above V2/VREF, TAP increases thrust."

From what we know so far, it does seem the engines were not producing sufficient thrust, during a period when it would also be crucial to maintain electrical output for the electro-hydraulic systems and critical electrical loads.

Reduced electrical output could explain the failure of the gear to complete retraction, maybe caused by a generator failing at the worst possible moment.

If there was an EFATO, the ability of the remaining generators to provide sufficient power might become questionable, as is highlighted with the load shedding system.

Other features which are unique to the 787 could be contributing factors in explaining the accident.

It is known the 787 will generally employ an extended take-off roll, and a relatively higher V1 and Vr, and also climb out less steeply than other aircraft. Using more of the runway would reduce the margin for aborted take offs.

With the evident lack of thrust early in the climb out, and failure to retract the gear, if V2 had not been maintained, the TAP system would have reduced thrust even further. Manually increasing thrust will be inhibited.
None of the above makes any sense. There are excellent videos of the takeoff. The aircraft was rock solid in yaw. The takeoff roll and rotation appear normal. Had the flaps been up they would have had a tail strike before getting airborne. The videos show a normal takeoff roll, normal rotation and normal initial climb. At some point below 200 feet AGL all thrust is lost. Here is a video of what a single engine failure looks like before reaching acceleration height. Note also how the wing looks when it reaches about the same distance the Air India video is shot from. At flaps five they appear up.

Subjects: EFATO  Engine Failure (All)  Gear Retraction  Generators/Alternators  Takeoff Roll  V1  V2

2 users liked this post.

Sailvi767
2025-06-30T23:52:00
permalink
Post: 11913954
Originally Posted by B2N2
Except:
​​​​​​
  • A \x91quick turnaround\x92 of a passenger aircraft is 2.5-3hrs
  • Fuel in CDG is no doubt more expensive then at DEL. Also a crew doesn\x92t just take extra fuel without dispatchers concurring
  • If anything it may have carried a little extra from DEL.
  • Turnaround was 2:38 or close to it.
  • Engines run on their own tank for take off. Two different tanks with the same contamination would be exceptionally rare.
  • A complete electrical failure due to some massive event combined with two tanks contaminated would be akin to a lightning strike on a lottery winner.

The longer this takes the more crew actions or lack thereof become the centerpiece of the investigation.
More then 1,100 787\x92s have been delivered and flying the last 14 years.
Hundreds fly every single day.
Not a whisper from any of the aviation authorities worldwide. No emergency AD\x92s..nothing.
Both engines run from the center tank on takeoff if it has fuel in the tank which was the case on this flight.

Subjects: Centre Tank  Electrical Failure

3 users liked this post.