Dreamliner Down in India

[jpilot77]

Are bleeds off takeoffs common on a 787?

All of the 787 systems are electric, the only bleed off the engines are for engine anti ice. Everything else is electric. Compression for the cabin electric, wing anti ice electric, flaps electric etc…

[pdw]

I am not going to speculate until I have seen PDW’s analysis. Lol

Most certainly, I need the isobar study and multiple wind readings from around the airport before I can come to any kind of conclusion.

AAHHHHH you beat me to it!

998hpa/to-Jaipur (farthest north and east) is lowest pressure stretching east/northeast of the airport (wunderground Ahmedabad airport data also nears 998hpa). “Smoke” would be drawn in/over along with that drier/hotter there (109f/43C air /7am Jhansi) gradual downslope from NE/ENE; an inversion, where 2-3kts breeze down the rwy is moving directly opposite of above inversion. The otherwise cooler airport 189ft elev surface air 97-98F/36-37C feeds-in under from a lot cooler source (ocean temp below 89F) than that 109F/43C or more air moving in higher (over/above that 180elev 05-threshold/airport area) a long ways downslope from farther northeast/ie Ratlam 1702ft elevation. Add 7-8F dry lapse rate for some higher data points … 5.4F per 1000’ of drop?

Edit: “Old Fella” .. that’s only one factor of cheese remember ..

[Old fella]

Most certainly, I need the isobar study and multiple wind readings from around the airport before I can come to any kind of conclusion.

AAHHHHH you beat me to it!

998hpa is lowest pressure stretches east/northeast of the airport (wunderground Ahmedabad airport data also nears 998hpa). “Smoke” would be drawn in/over along with drier/hotter (43C air) gradual downslope from NE/ENE; an inversion, where 2-3kts breeze down the rwy produces yet hotter ground effect (ie the heat coming off high noon asphalt) as well. (The cool airport surface air 96-97F/36-37C is quite a bit cooler that the 109F/43C farther east).

So this will drag down a B787-8 to its ultimate demise with a catastrophic outcome . Hard for an old dude like me to put this altogether so I can capture the picture. No doubt it’s time for me to bid fare thee well.

[pdw]

We always took off full power, but that’s never been the case with jets esp these big giants. However the performance calculations used are still relying on the same principles we’ve learned so well. We’ll soon see something concrete about those engines, hopefully.

[cdnavater]

AAHHHHH you beat me to it!

998hpa is lowest pressure stretches east/northeast of the airport (wunderground Ahmedabad airport data also nears 998hpa). “Smoke” would be drawn in/over along with drier/hotter (43C air) gradual downslope from NE/ENE; an inversion, where 2-3kts breeze down the rwy produces yet hotter ground effect (ie the heat coming off high noon asphalt) as well. (The cool airport surface air 96-97F/36-37C is quite a bit cooler that the 109F/43C farther east).

So this will drag down a B787-8 to its ultimate demise with a catastrophic outcome . Hard for an old dude like me to put this altogether so I can capture the picture. No doubt it’s time for me to bid fare thee well.

It’s not you, it’s him!

[pdw]

Look at a Koch chart (and the example they give you when you google it)

Try adding in a 10kts ENE inversion shear (DPS), showing up from northeast (Indore/1850ft elev or from Kota at 896ft 46C/115F noon and from Udaipur 1684ft 107F/43C … adding lapse rate makes it hotter.

How does that affect climb rate at the “635msl” density alt?

[sportingrifle]

Pdw…transport category performance data has very conservative assumptions built in to cater for environmental changes, pilot techniques, etc. For example the performance is calculated with 50% of the reported headwind, 150% of the tailwind, seversl seconds are allowed for pilot reaction time, brakes are assumed to worn, etc., etc.

Just curious, what is your “day job?” You have a way of looking at things we don’t often see.

[pdw]

Was farm operator/manager now looking after grandkids, selling 2ton tree-moving spades on the side.

Pdw…transport category performance data has very conservative assumptions built in to cater for environmental changes, pilot techniques, etc. For example the performance is calculated with 50% of the reported headwind, 150% of the tailwind, seversl seconds are allowed for pilot reaction time, brakes are assumed to worn, etc., etc.

So did everyone catch the density alt at “635msl” and reference that chart. Then you have noticed the example is 230 percent more runway and 75percent less climb (ie now 500fpm not 2700). But what would the example be if you DP-sheared in such climb out (a climb stumble) with even just five knots moving there as I’ve described above?

[cdnavater]

Look at a Koch chart (and the example they give you when you google it)

Add in 10kts ENE (showing at Indore/1850ft elev)

What do all those things do to a climb rate by “635msl”, let alone runway distance that was required just to get there?

Pdw,
A worst case temperature inversion should not bring down an airliner and most certainly not a B787, even an Engine failure at V1, we are talking 10% flight path degradation
https://safetymatters.co.in/temperature ... rformance/
Then, the actual aircraft performance could be affected only in the event of an engine failure at takeoff.

However, conservatism in the aircraft certified performance is introduced by the FAR/JAR Part 25 rules, to take account for inaccuracy of the data that are used for performance calculations. Although not specifically mentioned, temperature inversions can be considered as part of this inaccuracy.

Therefore, a temperature inversion could become a concern during the takeoff only in the following worst case with all of these conditions met together:

– The engine failure occurs at V1,and

– Takeoff is performed at maximum takeoff thrust, and

– OAT is close to or above T.REF, and

– The takeoff weight is limited by obstacles, and

– The temperature inversion is such that it results in the regulatory net flight path margin cancellation

and leads to fly below the regulatory net flight path

In all other cases, even if the performance is affected (inversion above T.REF), the only detrimental effect will be the climb performance to be lower than the nominal one.

The minimum climb gradient required at the point 35 ft above the runway for the second segment oneengine inoperative is:

– 2.4 % for twin engine aircraft.

– 3 % for four engine aircraft.

The margin between the net and the gross flight path is:

– 0.8 % for twin engine aircraft.

– 1 % for four engine aircraft
Assuming a 10°C temperature inversion (above T.REF) between the ground and 1500 ft, the effect on the aircraft performance will be as described in the following graph.

The first graph applies to an A320 fitted with CFM engines. However, the effect of the temperature inversion on the engine thrust is quite similar whatever the engine type.

(about 10 % thrust loss with a 10 °C inversion). Thus, the effect on the climb performance, in terms of climb gradient, will be similar whatever the twin-engine aircraft model.
The graph shows that for conservative conditions and particularly an engine failure at V1 and a temperature inversion of 10°C, although the gross climb gradient is affected it should not become a concern.

[Tbayer2021]

Look at a Koch chart (and the example they give you when you google it)

Add in 10kts ENE (showing at Indore/1850ft elev)

What do all those things do to a climb rate by “635msl”, let alone runway distance that was required just to get there?

Pdw,
A worst case temperature inversion should not bring down an airliner and most certainly not a B787, even an Engine failure at V1, we are talking 10% flight path degradation
https://safetymatters.co.in/temperature ... rformance/
Then, the actual aircraft performance could be affected only in the event of an engine failure at takeoff.

However, conservatism in the aircraft certified performance is introduced by the FAR/JAR Part 25 rules, to take account for inaccuracy of the data that are used for performance calculations. Although not specifically mentioned, temperature inversions can be considered as part of this inaccuracy.

Therefore, a temperature inversion could become a concern during the takeoff only in the following worst case with all of these conditions met together:

– The engine failure occurs at V1,and

– Takeoff is performed at maximum takeoff thrust, and

– OAT is close to or above T.REF, and

– The takeoff weight is limited by obstacles, and

– The temperature inversion is such that it results in the regulatory net flight path margin cancellation

and leads to fly below the regulatory net flight path

In all other cases, even if the performance is affected (inversion above T.REF), the only detrimental effect will be the climb performance to be lower than the nominal one.

The minimum climb gradient required at the point 35 ft above the runway for the second segment oneengine inoperative is:

– 2.4 % for twin engine aircraft.

– 3 % for four engine aircraft.

The margin between the net and the gross flight path is:

– 0.8 % for twin engine aircraft.

– 1 % for four engine aircraft
Assuming a 10°C temperature inversion (above T.REF) between the ground and 1500 ft, the effect on the aircraft performance will be as described in the following graph.

The first graph applies to an A320 fitted with CFM engines. However, the effect of the temperature inversion on the engine thrust is quite similar whatever the engine type.

(about 10 % thrust loss with a 10 °C inversion). Thus, the effect on the climb performance, in terms of climb gradient, will be similar whatever the twin-engine aircraft model.
The graph shows that for conservative conditions and particularly an engine failure at V1 and a temperature inversion of 10°C, although the gross climb gradient is affected it should not become a concern.

This is a fine example of Brandolini's Bullshit Asymmetry Principle

"The amount of energy needed to refute bullshit is an order of magnitude larger than to produce it."

[pdw]

Pdw…transport category performance data has very conservative assumptions built in to cater for environmental changes, pilot techniques, etc. For example the performance is calculated with 50% of the reported headwind, 150% of the tailwind …

Component on the nose is nearing zero (maybe two knots) at that time on this runway, and understandably a tailwind performance value would be applied if known — and accordingly pre-planning for any performance decrease there (a possible DPS shear) as well. The cooler 90F off-ocean inversion-supporting air (moist in comparison to above opposite flow) presses/underpins in from West/SW (see via wunderground airport data of Bhavnagar 90nm-SSW at 7kts SW 90F, Porbandar SW 190nm 3kts-W/89F, Kandla 86F/SW-2kts). The hot inversion (impressive east flow above) already starts showing-up/is-noticeable well west of the airport (drawn from and north of higher elevation at Rajkot 434msl early am) at the inlet between Bhuj elev 257ft and Jamnagar 69ft mid morning.

[The Raven]

I can't think of a scenario where both engines would fail at exactly the same time. If they failed at exactly the same time I can only think there must have been some corruption or fault in the FADEC system.

How about this for a possible scenario? They lose an engine at (or approaching) V1. I"m guessing the right engine. They continue the takeoff (hence the long take-off roll). They get airborne on one engine and in the heat of the moment someone thinks they are shutting down and securing the failed engine but instead shuts down the good engine.

Thoughts?

[Tbayer2021]

I can't think of a scenario where both engines would fail at exactly the same time. If they failed at exactly the same time I can only think there must have been some corruption or fault in the FADEC system.

How about this for a possible scenario? They lose an engine at (or approaching) V1. I"m guessing the right engine. They continue the takeoff (hence the long take-off roll). They get airborne on one engine and in the heat of the moment someone thinks they are shutting down and securing the failed engine but instead shuts down the good engine.

Thoughts?

This has happened multiple times before so its entirely possible. Last one being Transasia 235 in 2015.

[DanWEC]

To me, that theory doesn't quite check all the boxes. I don't know the specifics of the 78 sops, but in the bus you don't begin securing until well-stabilized, climbing and flying. No button smashing until then. I would assume the 78 is similar. Same with the Mayday call on a v1 cut.
With balanced field, there is usually very little spread between v1 and Vr as well.
It looks like power loss happened on the initial climb out just after rotation. Climbed, then sank. It was well above ground effect alt when that happened.

Personally, I believe the timing corresponds with selecting the gear up. I'm wondering if there was either a major electrical failure or otherwise that happened when retraction was commanded, or a sabotage using it as a signal. Scary stuff either way.

[mmm...bacon]

^ I’m of the opinion that some fancy malfunction that just happened to coincide with gear retraction, and has never happened on any other 787, is unlikely. Much better to fall back on the old chestnut f human error - someone has, (in a panic?), pushed the wrong button, or pulled the wrong lever…

[flieslikeachicken]

I can't think of a scenario where both engines would fail at exactly the same time. If they failed at exactly the same time I can only think there must have been some corruption or fault in the FADEC system.

How about this for a possible scenario? They lose an engine at (or approaching) V1. I"m guessing the right engine. They continue the takeoff (hence the long take-off roll). They get airborne on one engine and in the heat of the moment someone thinks they are shutting down and securing the failed engine but instead shuts down the good engine.

Thoughts?

I'm not sure about the 787, but I do know that other aircraft have a separate FADEC computer for each engine and the failure of one should not affect the other. I feel safe to assume that the 787 follows the same principle for a critical aircraft system.

The engine failure theory is easily proven or disproven by looking at the FDR data and the engines themselves. You can see if the engines stopped suddenly upon impact or if they were mostly stopped prior.

[DanWEC]

^ I’m of the opinion that some fancy malfunction that just happened to coincide with gear retraction, and has never happened on any other 787, is unlikely. Much better to fall back on the old chestnut f human error - someone has, (in a panic?), pushed the wrong button, or pulled the wrong lever…

I know, I get it, but then why actioning so early? Doesn't make sense. But, this is assuming SOP's were followed. Maybe there was some sort of warning and they just simply lept to an erroneous shut down as you mentioned. Seems implausible but then again much about this accident already is.

Here's a dubious question for the 78 drivers- Doubtful, but can you shut a normally operating engine(s) off by turning the masters alone off?

From any angle I can think of, there are several parts of this that just won't add up until we get more information.

[HavaJava]

Here's a dubious question for the 78 drivers- Doubtful, but can you shut a normally operating engine(s) off by turning the masters alone off?

They are called fuel cutoff switches and yes, you can shut down a normally operating engine at any time during the flight by simply selecting it to "cutoff". This is how we shutdown the engines at the end of every flight.

It is a detented switch so it can only be actioned intentionally.

Same as the Airbus, so maybe I misunderstood your question?

[DanWEC]

Here's a dubious question for the 78 drivers- Doubtful, but can you shut a normally operating engine(s) off by turning the masters alone off?

They are called fuel cutoff switches and yes, you can shut down a normally operating engine at any time during the flight by simply selecting it to "cutoff". This is how we shutdown the engines at the end of every flight.

It is a detented switch so it can only be actioned intentionally.

Same as the Airbus, so maybe I misunderstood your question?

Thanks, yes, same function, different name. That confusing word salad was the result of a phone edit.

[pdw]

There is some brief moment at liftoff where the "dust devil" has the appearance of a wing tip vortex.

Was the previous departure close ahead of it?

[pdw]

So this will drag down a B787-8 …. (?)

Was that a question ? And, I’m sorry about being so blunt .. was so entrenched in searching the pertinent data for preparing that explanation.

Answer to your statement is determined no by general consensus here so far. Now it’s also a matter of understanding (as our curiosity persists) how much it would take on the tail in this unusually hot inversion, and what are ALL the other factors contributing if it were so. The inversion air (hotter with height and faster from East with height) would have been moving along roughly SW perfectly incident from aft (from NE) of the takeoff direction (heading 224T) at a fair pace; so whatever that speed is can calculate first-of-all how fast it would ever need to be to make it so (to make that it’s take-down / “it’s ultimate demise”)

[Canoehead]

Hundreds... thousands of flights depart daily in these conditions. If the crash was the result of performance due to atmospheric conditions, then it's because of incorrect loading and/or incorrect programming where the airplane was configured for failure. And even then, a competent crew could possibly get out of it.

This has nothing to do with an inversion, a tailwind component or dust devils.

[rookiepilot]

I assume fuel contamination is all but ruled out — other flights departing of course using same fuel source?

Absent a catastrophic cockpit decision, doesn't look good, does it. Catastrophic Electrical failure? Would that kill both engines?

This guy makes a case for vapour lock - extreme fuel temps.

https://www.youtube.com/watch?v=XptrHxG9dDk

[CpnCrunch]

I assume fuel contamination is all but ruled out — other flights departing of course using same fuel source?

Absent a catastrophic cockpit decision, doesn't look good, does it. Catastrophic Electrical failure? Would that kill both engines?

This guy makes a case for vapour lock - extreme fuel temps.

https://www.youtube.com/watch?v=XptrHxG9dDk

The problem is there doesn't seem to be any evidence of vapour lock actually ever happening on a turbine engine, from what I can see. Also, when vapour lock does occur, it tends to happen on starting the engine. Once the engine is running and fuel is flowing from the tanks, it is much less likely (or impossible).

[Sulako]

I deleted about 20 posts that were nowhere close to the topic of this accident. Let's try to keep the discussion focused on the actual crash.