BA038 (B777) Thread

[Smilin_Ed]

Will:
If you think something more than 'converting' a cooler to a heater is necessary here, we are in complete agreement.I believe we are in agreement and I think any heating needs to be upstream in the wing to help prevent icing in the pipes as was experienced in testing.

Chris, yes it is the fuel but I think it more practical (cheaper) to modify the planes so that they can better tolerate water than to change the specs. Trying to keep water, and other undesirable materials, out of the fuel would be much more expensive and more frustrating than a strategically located heater in the airplane.

[barit1]

Liquid-fuel rocket engines use regenerative cooling (http://en.wikipedia.org/wiki/Regenerative_cooling_(rocket)), wherein the cryogenic fuel and/or oxidizer is used to cool the case and nozzle of the engine, and in so doing vaporize the liquid.
Kill two birds with one stone.

In a gas turbine engine, there is a strong thermodynamic case to be made for mid-stage cooling of the compressor airflow. It would not be a pretty picture, with additional air ducts or fuel lines running hither and thither, but it would be a useful way to heat fuel in the tank and simultaneously optimize the engine cycle.

I'm sure it's been considered and rejected because of cost and complexity, but who knows? If fuel approaches $10/gallon, should it be reconsidered?

[Mr Optimistic]

Have read through the thread but can't quite see if there is positive evidence that the blockage/impingement is at the FOHE or if it's by logical analysis/plausability argument only. Could some patient soul enlighten me ? Thanks.

[WhyIsThereAir]

Don't know about the thread (I've only scanned it) but the last version of the report I read said that yes, ice* blockage in the heat exchanger can cause the symptoms seen. However, it went on to say that the timing of things observed at the engine would tend to put the blockage some 20 feet farther up the fuel line, and they are at a complete loss currently as to how that can happen - they can't find a point 20 feet back that can feasibly be blocked by ice.

I think the summary (of the report, not necessarily this thread) is: did ice* blockage cause the problem? Yes. Was it in the heat exchanger? Don't know. Was it farther back? Maybe, but don't see how that could happen. More research is required, and more research is happening.

* The report goes to some lengths to note that the "ice" is NOT 100% water. It is a frozen slush of water and fuel, and the water makes up a fairly small percentage of the slush.

[Swedish Steve]

but can't quite see if there is positive evidence that the blockage/impingement is at the FOHE or if it's by logical analysis/plausability argument only. Could some patient soul enlighten me ? Thanks.

Ice blockage of the FOHE inlet has been demonstrated in lab testing. It was not expected and operational procedures have been introduced to alleviate it. RR has designed a new FOHE which is now subject of an AD.
There is a picture in this thread, and also in Flight Global.

[Smilin_Ed]

barit1:
In a gas turbine engine, there is a strong thermodynamic case to be made for mid-stage cooling of the compressor airflow. It would not be a pretty picture, with additional air ducts or fuel lines running hither and thither, but it would be a useful way to heat fuel in the tank and simultaneously optimize the engine cycle.

Please don't even think about ducting bleed air out of the engine. I had to investigate an accident where three of my colleagues died because of a bleed air leak. Yes, it was decades ago, and yes materials have improved, but bleed air is highly dangerous stuff. Introducing bleed air into a fuel tank frightens me and I'm fearless.

[Will Fraser]

barit1

In theory, if what you mean is transferring some of the heat of compression to the Fuel, it makes sense. Cooler air can be compressed further, and adds efficiency. The Thermodynamics are beyond me, I'm more a mechanical sort, and tend to agree that running Fuel through or even around the second hottest part of the engine, seems problematic.
Intercooler?

Smilin Ed

727, LAX ??

Douglas rules the waves. Boeing, not so much

[Smilin_Ed]

smilinEd
727, LAX ??No. Navy A-3 in about 1972.

[Dairyground]

Back in post #2473, Pinkman says:


This is essentially a refinement of interim report 1, tidying up some rough experiments. It's easy to criticize the slow progress but it's really difficult to simulate - think of the early wind tunnels.

At the end of the day, there needs to be a dedicated interagency fuel research centre to physically model these issues accurately, using a combination of actual engines and actual fuel systems in environmental test chambers (imagine!) and maybe even including extended duration high altitude flight testing. Irrespective of the current case, this kind of facility will anyway increasingly be needed when biomass derived fuels start to penetrate the market.


Using actual engines and fuel systems is probably neither the least expensive or most efficient way to go about investigating fuel system icing. Small-scale lab bench and workshop rigs, with a bit of mathematical modelling, will be a much more effective way of identifying the relevant parameters and their interaction.

On a lab scale, it should be relatively easy to identify the dependency of ice accreation rates on pipe external temperature, pipe size, internal surface characteristics, fuel temperature, fuel flow, fuel composition, including water content, effect of flow rate on the stability of the ice, and so on. Only when these elements are reasonably well understood will it be possible to predict what will happen in a full-size system, and reasonable to verify those predictions.

Perhaps such investigations are already under way in the industry. If not, it seems likely that they are a potential source of PhD theses in accademia.

On a slightly different tack, the AAIB report suggests that it was difficult or impossible in many cases to observe ice build-up inside their test rigs. I should have thought that techniques such as ultrasound would have been effective, and that it would not have been too difficult to send a miniature camera through the system.

[Mr Optimistic]

Isn't it unsettling that even with an intact aircraft, all the systems ready to be examined in any detail you like, all the witnesses standing ready, fuel still available in the tank, all left in a convenient location and with time to think, there should still be any uncertainty ?

[PETTIFOGGER]

Mr Optimistic, Hi.
I am not sure what uncertainty you are referring to and why that would be unsettling, particularly after Swedish Steve's post just above. Can you say more?
rgds, pf

[Mr Optimistic]

Thanks for the reply. Have read through thread and seen discussions on the meaningfulness of specifications, anxiety about FAME (and about the possibility that there is some unknown factor which isn't even tested for), questions over twin engine ops for the airframe/engine combo, but there seems to be no clear smoking gun.

This gave me the impression that the ('interim' ?) findings are based on plausibility: cold long flight, fuel starvation, there is water in fuel - so ice is a main suspect, where might it most likely accumulate ? Yes we can mimic that failure mode in the lab, so lets go with that one then as NFF will have implications.

If it's so plausible now mother nature has pointed it out to us why didn't the original design anticipate it and why is it so rare an occurrence ?

All very well to cover office walls with fault trees, cut-sets and 10 to the power of minus 9, but this surely should be cut and dried forensic engineering.

And I haven't got that impression from reading this thread (no headline claiming 'CRACKED IT').

Doesn't this one need putting to bed more firmly ? (..the issue, not me !).

As an after thought, has the fuel system on the 777's with alternative engine supplier demonstrated differences in design to explain why it is only RR ?

[4greens!]

In oil refineries it is common practice to pump large amounts of heavy lube and fuel oil for distances of up to a mile.In order to keep the oil from cooling and becoming too viscous to pump "trace heating" is used. This consists of a small diameter pipe wrapped round the pipeline which is then heavily insulated. Low pressure steam is passed through the tracepipe.By substituting steam for electrical resistive heating tape and insulating the fuel pipe is it not possible to warm the fuel before it gets near to the engine? This would be a more elegant solution than piping bleed air around the wing. Just a thought.

[Fargoo]

fuel pipe heating
In oil refineries it is common practice to pump large amounts of heavy lube and fuel oil for distances of up to a mile.In order to keep the oil from cooling and becoming too viscous to pump "trace heating" is used. This consists of a small diameter pipe wrapped round the pipeline which is then heavily insulated. Low pressure steam is passed through the tracepipe.By substituting steam for electrical resistive heating tape and insulating the fuel pipe is it not possible to warm the fuel before it gets near to the engine? This would be a more elegant solution than piping bleed air around the wing. Just a thought.

This is exactly what is used in the cargo bays to stop water from freezing inside the service pipes (resistive heater tapes that is). I'd imagine it'd take a load of research and money thrown at it before they'd ever certify electrical heater tapes on a fuel system pipe.

[cockney steve]

I'd imagine it'd take a load of research and money thrown at it before they'd ever certify electrical heater tapes on a fuel system pipe.

Already well-proven in industrial apps. However, the current needed to pump that much heat into such an enormous flow-volume would require some seriously big alternators and cabling. HUGE power-loss!

mid-stage heat-exchange intercooling would appear to be the simplest solution,a portion of the surplus,returned, warmed fuel could recirculate through the wing/pylon-piping, whilst the rest returned to the tank.

although power-losses are involved, the thermodynamic gain would offset some or all of this, thus making a virtue from necessity.

[Smilin_Ed]

Steve, your analysis of electrical heating problems is right on. Not very practical. Also, I don't have much problem using air bled off the engine as long as it stays in the nacelle and can't leak out to burn things like wings. I'm really paranoid about that. :ok:

[Markieboy]

I still don't believe an ETOPS airliner can have BOTH engines display the same behaviour at the SAME time due to fuel freezing or boost pump contamination.

It can't happen. Sure, it can happen in one tank and after a while maybe even in the other but AT THE SAME TIME? Forget it.

The chances of fuel freezing in both tanks at the same time is mathematically irrelevant.

Just my .02.

[barit1]

Not knowing the details of the Trent/777 installation -

The HP fuel pump is typically sized to pump fuel for the SL takeoff condition, which means it is oversized in cruise, and VERY oversized in descent. It being a positive-displacement pump, the excess fuel must be routed somewhere, and depending on where the excess is dumped, it can either create an unwanted thermal runaway, or else solve an overcooled condition.

Or did I read that the RR HP pump is a variable-displacement type, in which case the above is null and void? :confused:

[Swedish Steve]

Or did I read that the RR HP pump is a variable-displacement type,

No. the HP fuel pump is a gear type positive displacement pump. Remember it is turned by the gearbox, so the speed is proportional to engine speed, and so therefore is the output.
Inside the FMU is a Pressure drop and spill valve which controls the downstream pressure by spilling fuel back to the HP pump intake.

[barit1]

That's what I thought.

My point is that pumping fuel up to burner pressure takes a lot of energy, and when there's an excess of high pressure fuel available, that's heat that can be put to good use.

Or not. :uhoh:

[WhyIsThereAir]

I still don't believe an ETOPS airliner can have BOTH engines display the same behaviour at the SAME time due to fuel freezing or boost pump contamination.



Doubtless your concern is not yours alone, which is perhaps one reason we don't have "the answer" from the NTSB yet. But keep in mind the current theory isn't just "fuel freezing". That is only part of the problem.

The current theory runs like this: during cruise the fuel flow was fairly light and equal, and both lines iced up about equally. Not enough to starve the engines, but enough to restrict flow to about the current flow.

Now the plane descends and warms. The ambient is warmer than the fuel, and the line going down the engine support is quite warm on the outside. The ice begins to thaw nearest the tubing wall, but is still frozen inside. We now have a lot of "loose" slush, but because it is impacted and has minimal flow past the inside (and thus minimum pressure exerted on the ice mass) it isn't going anywhere.

Now the plane has to counter some ground turbulance, and as it just happens, this results in three cycles of rythmically increasing and decreasing fuel flow. You may have experienced how one push on something stuck won't get it lose, but if you push on it rythmically a few times you will eventually get it lose. This isn't just your imagination; there are well-understood reasons why this happens. The theory seems to go that this has broken lose the ice in the lines, and probably got some (but not all) of it down to the heat exchanger.

Now finally there is a call on both engines for massive fuel flow compared to what has gone before. This causes all the ice to break loose and pile up against some obstruction, resulting in a major blockage. It is possible this obstruction was the heat exchanger. It is possible that it was some place upstream in the fuel piping that has not yet been identified. The result would be approximately the same, but not identical.

So there is a solid theory, based on both physics and experiment, that can (almost) account for the observed symptoms in the crash. There is also a demonstrated way (blocking the heat exchanger) that could cause this result. So there is reason to fix the heat exchanger post haste. The problem is that blocking the heat exchanger doesn't quite account for all of the observed symptons. So they can't say "fix the heat exchanger, case closed". More research is unfortunately needed, and probably solutions to other problems once they are discovered.

[Pinkman]

Markieboy

I still don't believe an ETOPS airliner can have BOTH engines display the same behaviour at the SAME time due to fuel freezing or boost pump contamination.

It wasn't at the same time, it was seven or so seconds different. And that in itself was the most powerful piece of information that said it was a common cause but not necessarily an instantaneous common mode fault like (for example) an electrical bus, relay, or fuel pump failure.

Obviously you are a statistician. I'm a fuel guy and I have a different opinion, which is that identically built engines constructed to incredibly close and repeatable tolerances operating on identical fuel in an identical environment might well be expected to suffer identical failures at more or less the identical time.

There is another thread running on PPrune concerning the amber thrust reverser deployed caution lights that came on after V1 on the take off roll at Johannesburg recently for both inboard engines on a 744. There is a hell of a lot more potential variability in those circumstances over a shorter period of time but not only was there a common cause, the lights came on within a few seconds of each other.

As Nicolas Cage said in City of Angels "just because you don't believe it doesn't mean it isn't true"

Dairyground

You have kind of answered your own criticism by explaining the difficulties that the AAIB are having replicating the incident. But introducing artefacts like cameras into a fuel icing trial is just another example of us not learning from experience: even if you could do it, you change the dynamics of the fuel system such that it is not representative of the actual conditions.

Examples:

- When the original jet engines were tested using frozen chickens fired into the rotating turbine it was wrongly assumed that the test more or less replicated what would would happen when an engine encountered a bird at altitude.

- One reason the Kegworth 737 - 400 crash happened was because CFM extrapolated the data from the -B1 engine series to the -C1 engine on the -400. And we now know that the engine didn't behave exactly as predicated by the computer model or the ground run that used a modified spinner.

- When RR did the containment tests on a trent they may have modelled a blade separation, but they were still required to write off an engine by doing a real-time engine test where the blade was actually ingested.

I wasn't advocating mandatory in vivo testing of every powerplant with every fuel: I know that in vivo tesing is expensive. I simply want to see a dedicated low temperature research facility which has the laboratory testing you cite but which then has it confirmed by the in vivo testing of actual powerplants on a variety of fuels in a variety of environments. My understand that Boeing and the USAF have been doing it for years for miliatary applications.

[Smilin_Ed]

IMHO, regardless of where the restriction formed, all of this still points toward a need for in-tank fuel heating.

[lomapaseo]

IMHO, regardless of where the restriction formed, all of this still points toward a need for in-tank fuel heating

isn't that what got TWA800 into trouble?

[FlyingCroc]

That was a missile.

[Will Fraser]

TWA800. Not heating caused. Empty, 'fume filled' Center tank, and some 'arcing' internal wires, as I recall. Much talk of the need for 'inerting' tanks, like the 787 does. The need for inerting cropped up due to the extensive use of composites. No 'Faraday Cage', no 'bonding' (in the sense of 'electrical', not composite.)

[Smilin_Ed]

Will is right on the cause for TWA800.

[phil gollin]

If people would read the thread rather than just skimming it, they would see that the second interim report only got indications of fuel slush icing up the heat exchanger by going totally away from both the max spec of water in fuel spec, the sample taken from the crashed plane and the probable (i.e. guess) mixture based on the Chinese fuel and likely change during flight.

The AAIB cannot (or at least not publically) replicate what happened. There have been a couple of rather inflamatory press releases from other sources which do not seem to have anything to back them up other than either wishful thinking or extreme caution.

IF (and it is a big IF) it is found that fuel slush is the problem then new certification rules will need to be established and ALL plane/engine combinations will need to be checked.

.

[Will Fraser]

Too many watch the shiny object, (FAA, AAIB, etc.) The problem is not the FOHE, Water does NOT belong in Fuel. The Piping picture in the Report is Upstream, and the quantity of Ice is disturbing before any discussion of the Trent starts to distract the public. Modifying the Trent and assuming GE and PrattWhitney are invulnerable to the Ice produced on test is presumptuous. Assumptions about Fuel caused BA038's demise, not the impacted FOHE.

It's the Fuel. Tanks weren't getting sumped, water was allowed to build in tanks between flights, improper engineering and sloppy Fuel practices are a danger sign, no less troubling for the entire fleet of a/c than Twins.

Where is the GC tape, the MSA from the Accident samples? That cannot be privileged or secret in a free society, anybody privy to the complete data generated in the Investigation? Beyond a certain reasonable time interval, (which I protest, obviously) the complete results need to be made public, not sequestered behind locked doors like in some ancient Eastern regime.

[pls8xx]

Fuel /ice slush? Think about this. At the point where the pump goes into cavitation, the fuel pressure at the pump inlet falls to near zero. And the near zero pressure will extend back through the pipe to the blockage. On the other side of the blockage the pressure will be one atmosphere, plus any head from elevation below wing fuel surface, plus the pressure added by the wing boost pump. That is a major pressure difference across the blockage of well over 30 lb/ in. Also the small area that is not blocked is carrying all the fuel flow. If the pipe is 95% blocked per the report mock up that caused cavitation, then the velocity as it passes the blockage is 20 times normal. Still think it was slush?

[FlyingCroc]

Fuel Flammability
The NTSB's theory is that some unknown spark ignited the Jet A fuel vapors inside Flight 800's center fuel tank. This theory depends on 2 things: a) sufficient fuel vapors at the proper fuel/air mixture; and b) a sufficient spark to ignite the fuel vapors. Neither condition has been found to have been present in subsequent tests. In Boeing's recent filing with the NTSB they have stated that they have not found any source of spark in Flight 800. The NTSB would have you believe that Jet A fuel vapors are a virtual bomb waiting to go off, yet every day hundreds of 747's are sitting on hot runways in places like Saudi Arabia, India, etc. with empty center tanks and none have ever exploded. Every day aircraft with empty fuel tanks are hit by lightning, a spark thousands of times greater than necessary to ignite this vapor, yet these aircraft do not explode. Why, because the fuel vapor is not explosive.

The Flight 800 Investigation (http://twa800.com/pages/fuel.htm)

[Will Fraser]

pls8xs

Technically, in the cavitation incident described it is at the Outlet of the HP where the Pressure is zero. The HP is Upstream of the FOHE, so the FOHE had exactly what to do with the Fuel Starvation ? This is why the results have been portrayed as possibly (sic) indicating upstream (of the HP) blockage.

The lack of a positive conclusion should not connote mystery, it should infer a manufacturing of escape scenarios for the Report. It also allows for leaving things the way they are (but for AD), at least in public disclosure.

FlyingCroc

Not wrong. I haven't stated I concur with NTSB, I merely stated the conclusion of the investigation. I have some reservations about the 'Explosion' of the tank. The Japanese guy who croaked in the 'seat bomb plot' was sitting in a seat that was behind (in front of?) the center tank, a blunder by the one who planted the downward exploding charge.

[FlyingCroc]

Will, I thought you were smart enough not to believe these NTSB liars. Now back to the topic BA038.

[chris weston]

FlyinCroc sir,

Agree.

You need an oxidising agent (usually O2 from the air) to go with the reducing agent (hydrocarbons various) before you can get a combustion reaction - as well as the activation energy having been exceeded by the spark from the faulty wiring.

As there was no inerting and the tanks are vented to air, its simply an input output calculation as to whether or how much O2 is present.

My money is on very very limited amounts of O2 being there - the Vp of Jet AI being > the diffusion inwards of the air.

In Calcutta no chance - paradoxically the higher the ambient the safer the "empty" tank.

Now what was the temperature profile for TWA800 ..........

Yes we could do the sums but this is so far off thread that I confidently expect the mods to intervene ...........

CW

[ChristiaanJ]

Water does NOT belong in Fuel.
Your remark triggered a thought.....
Of course it doesn't belong there, and neither do other contaminants.
Yet they get in there sooner or later.
So, shouldn't a fuel system be designed from the outset for far worse crud than meets the "official" fuel specs?

Maybe a lousy analogy, but with perfect ATC, etc., there should be no other aircraft in my airspace. Yet we now have TCAS, and rightly so.
With perfect nav, CFIT should not exist. Yet we have GPWS, and rightly so.

With perfect fuel, this should not have happened. Yet it did. Maybe fuel systems should also have be designed for when 'sh!t happens'?

Whatever happened this time, the system was not "fault tolerant" enough.

CJ

[Will Fraser]

You raise the 64 dollar question, Chris. For fifty years the USAF and RAF have been flying up to FL600 and higher, to my knowledge, not one a/c has been lost to Fuel ICE. That in the days when jet fuel was.... well, ask Pinkman, it was crap.

With the benefits of metallurgucal, refining, electronic and systems progress, we now worry all of a sudden about 'mysterious' effects of water at altitude? Give me a ----ing break. The 'clog' in a heat exchanger brought down a 200 million dollar a/c ?

Any Lear owner knows to add a little Pristtm, but fuel monkeys and Pilots can't be bothered to sump a big rig ? "It's Frozen, wouldn't do any good."
Right then, 777bravosierra ready on the Right. Oooh, chemical mysteries, tubesheet maladies, Amoebic slurries, micro nucleated crystalline cascades disrupted by non-cadent thrust demands............what a bunch of Bull-ess. Does Dr. Fuelinstein not really know ? Or is he just too embarrassed to say ? What does a sump exercise cost ? Mr. Beanie knows. How many add up to 200 million dollars and the possibility of the need for 200+ caskets ?

Edit: USN as well as outfits listed above, sorry

[Smilin_Ed]

So, shouldn't a fuel system be designed from the outset for far worse crud than meets the "official" fuel specs?


Yes. Engineers are taught to build in a safety factor on every component. That's why wings don't come off as you get to the published limits. Water, and other contaminants, will inevitably get into the tanks and the fuel system needs to accommodate that.

[ChristiaanJ]

Yes. Engineers are taught to build in a safety factor on every component. That's why wings don't come off as you get to the published limits. Water, and other contaminants, will inevitably get into the tanks and the fuel system needs to accommodate that.Ed,
I happen to be an aeronautical engineer, and I know that.....

But when I designed in a 1% resistor into an AFCS system, I already knew it would be at least that, and more likely 0.2%. And that anything over 1 to 2% would be found out by acceptance testing before the system ever even went on an aircraft..

Here, we may be dealing with something that the engineers did not build in enough safety factors for... quite simply because the design was based on "the published limits" for the fuel itself.

CJ

[Smilin_Ed]

CJ:
Here, we may be dealing with something that the engineers did not build in enough safety factors for... quite simply because the design was based on "the published limits" for the fuel itself.


I agree completely. I think they designers didn't consider very long flights across arctic airspace. The cold-soaking exacerbated the situation. I think it just happened that ice, slush, or whatever we want to call it caught on some protrusions in the piping and other components. At the risk of being slammed for repeating myself, it's time to start heating the fuel in the tanks before it has a chance to clog any downstream component. It's either that or limit the aircraft to warmer air and/or shorter flights in very cold conditions. The cost of retrofitting will be high but won't equal the cost of even one repeat accident.

[WhyIsThereAir]

May be a much cheaper and simpler solution than heating. Keep the fuel moving. If it is flowing right along, there is a pretty good chance that it isn't going to have time to build up on a decently smooth hunk of fuel line. How much flow rate you would need and how much good it would do are calculable.

Someone mentioned that the HP pump is a nice inefficient hydraulic design where it is always making lots of flow at full pressure, and the excess fuel is recirculated back to the pump inlet. Add some hose and recirculate it back to a jet in the tank directed at the suction inlet strainer. Or even to a T in the inlet strainer assembly. Or point it at the tank sump and let it mix with any water present. Whatever the CFD analysis indicates if the best point to inject the recycled flow. (And the HP pump outlet flow is going to be warmer than the inlet feed by some amount, so you will get some minimal fuel heating.)

[Will Fraser]

The Pump is driven by the engine gearbox, which in GE has its own heat exchanger interface with fuel. The HP doesn't pump a great deal more than the engine requires, and the spill is a fairly closely calculated flow that is more a safety consideration than a potential Gross Tankage circulator. EPR is Fuel reliant directly; the 'Safety' factor not even a critical one, if the fuel isn't enough, the engine keeps running, but at a rate that is flow dependent, as BA038 demonstrates. What's critical is to keep the Flame lit, and not add too much fuel.

All I can do is repeat that Water needs to be out of the Fuel. Including the mystery water that comes from secret places that are mysterious and cause unknown boffins to build imaginary 'test beds' that keep the public distracted until they lose interest. Why heat fuel when sumping and caution are enough ? I say we make them choose; frankly I'd choose better Fuel supervision, but that's me.

[Rightbase]

No water in the fuel at cruise - too cold, it is all ice.
Descent to a surface still below freezing - atmospheric ingestion contains water vapour which at lower altitudes condenses as frost on the cold tank surface.
If ambient stays below freezing, frost stays on the tank walls. Nothing to sump.
On the return journey, same story except that at lower levels the ambient is above freezing and the frost melts.
The melt water from the centre tank is sent into the still cold fuel in the two main tanks where it freezes again...

[Will Fraser]

Rightbase

I would acknowledge all your conclusions. I don't see anywhere that you think it is ok, this water in fuel. That leaves sumping after melt at a suitable location. Because something is difficult should not mean it gets a box checked, because to eliminate the water isn't 'easy' ...

It is the tolerance of water build up in 038 over time that is the problem; Boeing had to inject water into the fuel to reproduce the accident conditions.

Will

[Rightbase]

... warm refuelling.

Water in fuel tanks is inevitable and you are right - sumping is the answer - but it only works above freezing point.

[Will Fraser]

There's already hot hydrant, but in any case the infrastructure exists, it just takes money and the will.

[Smilin_Ed]

Assuming that you do pump warm fuel into the tanks, how long will it take for any water, frost, or whatever to condense and settle at the sump drains? If the next flight is only an hour or two away, is that enough time?

[Will Fraser]

BA038 was on stand overnight....afaik

if it was five hours, that's 40 million an hour and a fractured leg.

[Rightbase]

is what happens after the frost in the centre tank melts, when the fuel purge pumps get hold of the melt water.
A bit of clever redesign might make the refreezing of this melt water in the cold main tanks slow the purge process rather than the engines.

[barit1]

Will F:
...The HP doesn't pump a great deal more than the engine requires, and the spill is a fairly closely calculated flow that is more a safety consideration than a potential Gross Tankage circulator.

Not quite true, except at SL. But you gotta consider the whole envelope.

Think about this: The HP pump flow rate is directly proportional to core RPM, and is independent of altitude. Thus if there's a small flow margin at SL, there's a big excess at altitude.

Further: If idle speed is 70% (for discussion purposes...), then the HP flow rate at idle is 70%, where the actual engine burn rate is maybe 10% (or less). Therefore the extra 60% has gotta be bypassed.

STILL further: Idle at top of descent combines the altitude bypass AND the idle bypass, meaning there's a potential local overheating (through recirculation).

It's this significant excess, or bypass, fuel flow that is the question. If it's not gainfully employed, you get hot spots & cold spots in the fuel system.

[WhyIsThereAir]

Even ignoring the heat, there is significant fuel flow, several times the idle and cruise requirements. Ice has a fairly hard time sticking to reasonably smooth tube in high flow conditions. So the flow itself would likely prevent ice buidup. The heat would also help, even if a fair amount of it was lost by the time the recirculation got back to the tank inlet.

[etsd0001]

BA038 may well have been on the ground overnight, but what was the ambient temp overnight? What time was it refuelled? I bet about 3 Hrs before dept, as is standard. Not enough time after the refuel to allow any melting & settling for a meaningful water drain

I have been unable to do the sumps on a DC10 after it has been in a hangar for 12 hrs on a UK winters day because they were still frozen.

[Will Fraser]

Maybe when the Glacier starts to impact Fuel capacity this problem will get attention. Was what was frozen solid in the tanks what was left ? Was the a/c actually totally OOF ??

[chris weston]

Just when you need it Global Warming lets you down! Yes yes extreme weather etc ad naueum .

More seriously I very much take Wills glacier point, hyperbole in action but he's right to pose the question.

How many fueling cycles, cold soaks, limited efficiency sumpings does it take to build a glacier I wonder?

And .........of course we lost the contents of the centre tank on impact.

CW

[Rightbase]

Good question for the general case, Chris, but IIRC BA038 was pretty well water and ice free before starting the 2-way trip to Beijing and back.

So irrespective of where it collected, where did it come from?

[ChristiaanJ]

I followed most of the thread, so my remark is not meant to be fatuous, just very summary...

Good question for the general case, Chris, but IIRC BA038 was pretty well water and ice free before starting the 2-way trip to Beijing and back.Says who?
Or was this the icicle that broke off the glacier and broke the camel's back?
Or the slush puppy that finally choked the FOHE?

CJ

Edit: see Rightbase's post below. I concur. Back to base one, largely! Post #1805 is on page 91, to avoid anybody doing a tedious search.

[Rightbase]

Says who?Post #1805 (http://www.pprune.org/rumours-news/340666-ba038-b777-thread-91.html#post4377055) refers .....

PS - it is a real pity they didn't find melt water in the FOHE in their first inspection after the episode. They will know where to look next time.

[Pinkman]

I just dont buy the simple water theories. The water-carrying capacity of a fuel is finite and varies with temperature. AFAIK the tests have not been able to reproduce the fault without direct injection of water, a situation that would not occur in real life. I am not a conspiracy theorist but I am convinced there is something else fuel related going on.

PS "hot hydrant" doesnt mean "hot" or "warm" in the temperature sense. It simply means that the fuel is continually under positive pressure in the fuel trunk line to the apron service points, in the same way that your house electricty sockets /outlets are "hot" or "live" all the time. Keeping it this way prevents water and dirt entering the fuel line although it does mean that there is an increased risk of fuel leakage which is why there are (or should be) leak detection systems running along the pipe conduit.

[Smilin_Ed]

I have read the whole thread but most of it was several months back so I'm vague on some of it.

As I recall, the fuel from the aircraft which was tested after the crash was within specifications with regard to water content, but that would not have revealed the water present before the flight. Any water uploaded with the fuel or present in the tanks would have begun to migrate to the drain sumps and the sumps for the in-tank pumps before and during the flight. Some of it would even have been pumped through the engines. Therefore, was it in spec, as far as water is concerned, when it was loaded aboard? While we can test the fuel in the tanks in Beijing, how we can tell what the water content of the fuel in the aircraft was before or during much of the flight. Does anyone really know? I don't think so.

AFAIK the tests have not been able to reproduce the fault without direct injection of water, a situation that would not occur in real life.

Were the tests conducted with actual fuel from the aircraft or with fuel obtained from some other source? Presumably, fuel from any other source would be more or less water-free, so it would be mandatory to inject some water to get any icing in the pipes and FOHE.

[Pinkman]

The current arrangements represent a fairly good balance between cost, complexity, and specification. Thats not my opinion, its the opinion of almost everyone in the business. There are over 20 steps in the supply chain for managing quality and checking specifications (including centrifugal (coalescing) separators and microfiltration that you all are going on about). The important thing to understand is that the supply chain QC checks take place in a controlled environment. Aircraft already have filter screens against gross physical contamination. Moving water filtration systems to a aircraft is a complete non-starter because:

1) it moves the quality control operation to an uncontrolled environment
2) it adds weight and fuel burn to the aircraft (have you ever SEEN the kit that is used? weighs about half a tonne) Facet vertical coalescer separators, API-1581, Category C, Type S, Fifth Edition, aviation fuel filtration applications | CLARCOR (http://www.facetinternational.com/avfilter1.htm)
3) You would have difficulty inspecting and changing filters safely and inevitably it would get forgotten until, oops
4) The cost of miniaturizing the components would be astronomical

Forget it.

And yes water in fuel systems is inevitable because of the continual ingress of air through the vent which has moisture in it and no its not just a problem at sea level, all air has moisture in it which then freezes and condenses on the inside skin and forms free water which then dribbles down to the bootom of the tank and gets reabsorbed into the fuel in an free water:dissolved water equilibrium situation depending on temperature / density of the bulk fuel .

And in any case who said water was the issue?

Smilin_Ed no, the tests were not done with the actual samples (there is not enough of it) so they faked up a test batch. That didnt reproduce the problems. So they actually injected water into the fuel and eventually managed to get ice rime buiding up on the inside of hoses and on the FOHE plate.

[Smilin_Ed]

Pinkman, do I understand it correctly that they injected more water than was found in the fuel in the plane?

[Swedish Steve]

We are barking up the wrong tree here.
The water in aircraft fuel tanks is not introduced by refuelling. It is normal when refuelling to take a sample from the bowser/dispenser. The apparatus to do this is built into the truck. This sample is then tested for density and water. This is normal, and done all the time by refuellers. A small sample of the supplied fuel is drawn through a Shell water detector capsule by a syringe. In all my years refuelling aircraft, I have never seen any water detected.

The water in fuel tanks comes from the air in the tank. If the empty tank is full of humid air, the water will settle into the fuel on refuelling. Some aircraft have complicated systems to remove this water. The best I have seen was on the Tristar. A system of jet pumps and small bore pipes sucked up all the water from the bottom corners of the tanks and sent it into the engine feed system. I spent many happy hours cleaning these jet pumps as they became clogged, usually with bits of sealant from the tanks. Even the B777 has a much simpler system of water scavenge to accomplish this. Obviously on this occasion it didn't work.
Also the tanks are sumped by technicians about every day by draining liquid from the bottom sumps of the tanks. This is difficult in the winter as the water will freeze, but is done when practical. I have done this many times, and rarely seen more than a few cc's of water in the drain bottle.

[cockney steve]

As many Japanese car owners will have noted, there is a relatively cheap and simple way to eliminate atmospheric pollution.

Automotive Brake Fluid is extremely hygroscopic, a feature which dramatically lowers it's boiling -point and helps the system rust from the inside.

The wiley orientals put an inverted soft rubber "top-hat" under the filler-cap....as the fluid level drops, so does the membrane (retaining -cap is vented, as normal.

Now, Concorde's tanks were lined with a flexible-rubber in it's latter days , so it's not an insurmountable problem materials-wise.

I appreciate there are srructural members, baffles and the like to contend with which may necessitate separate "compartment" bags which could be pinked by a standardised coupling. A metal outer-tank would still be required for mechanical strength and containment of the "bladders".....as fuel is removed, the bladder collapses...any water condensatewould collect on the OUTSIDE of the fuel-bladder and inside the structural retaining tank which would need draining, of course.

This doesn't come without a weight penalty, but IMHO there's a major safety benefit (as anyone who'se experienced brake-failure will testify :} )



Going back to the fuel spill-return /heat-exchanger idea,- coaxial pipework with the warmed return on the outside would also insulate the supply from ambient temperature. any failure of the inner-pipe would merely "short-circuit" the rerturn /flow path A leak in the return would be no different to what would obtain in the present layout. again, a safety benefit at minimal penalty.

Appreciated that I may well be talking poppycock,but just sometimes, the bystander sees something the participants miss.

[sooty655]

The water in aircraft fuel tanks is not introduced by refuelling. It is normal when refuelling to take a sample from the bowser/dispenser. The apparatus to do this is built into the truck. This sample is then tested for density and water. This is normal, and done all the time by refuellers. A small sample of the supplied fuel is drawn through a Shell water detector capsule by a syringe. In all my years refuelling aircraft, I have never seen any water detected.


Looking at the condensate due to humid air, let us consider the worst case of an empty tank full of saturated air at 30C. The mass of water could be up to 30g per cubic metre (i.e. 30cc water or six teaspoons-full per cubic metre). I am not surprised that you seldom find much water in the sumps.


IIRC BA038 was pretty well water and ice free before starting the 2-way trip to Beijing and back.


Can't all be right, guys. :confused:

At the risk of stating the obvious, either

1) There was water in the uploaded fuel, or

2) The amount of water condensed from the incoming air was much greater than calculated, or

3) The aircraft hadn't been sumped adequately before the flight, or

4) It wasn't ice in the fuel system which brought down BA038.

Sooty

[Rightbase]

It isn't a case of either-or. It is and-and-and.

My (amateur) analysis of water source candidates based on information available is:
3Kg Max dissolved moisture at Beijing uplift (AIB all tanks)
2Kg Max entrained moisture at Beijing uplift (AIB all tanks)
Max adiabatic ingestion into centre tank (single air mass assumed):
0.4Kg descent to Beijing 0 degrees @ surface = 4.8 mg/litre
1.2Kg descent to LHR 15 degrees @ surface = 12.8mg/litre
Max adiabatic ingestion into main tanks (total for both tanks)
0.2Kg Beijing
0.7Kg LHR
Plus an unknown amount caused by centre tank fuel purge jet pumps sucking air for two and a bit hours after the tank is emptied (this may be the AIB's 0.14ltr (=0.14Kg) drawn in through the fuel tank vent system)
Plus any remnants of dissolved and entrained LHR uplift
Plus trapped water that cannot get to the sumps (0.35 litres total found in the main tanks at the earlier inspection - AIB) which is almost certainly totally innocuous.

The total is something like 8 litres max.

About a quarter of the uplift would start in the centre tank, so the centre tank could contribute some 2 litres or more. The centre tank is IMHO significant because instead of sucking air the fuel purge pumps will inject its water into the cold main tanks once the centre tank warms up above freezing.

[phil gollin]

Re. water amounts/tests

IF you had bothered to look at the thread, and the second interim report you will see that the tests are on "out of spec" fuel (90 ppm ????) and were still faked/forced to get some sort of problem.

The fuel in China has been stated to have been in spec (or "exceeded" spec) (70 ppm).

The second interim report goes into the samples taken in remaining tank (40 ppm ???????) and likely fuel conditions.

It is no good setting new hares running if they have already been shot.

See, for instance, post 2476,

[Pinkman]

Smilin_Ed

Phil Gollin's post effectively answers your question - I would have basically said the same.

Pinkman

[ChristiaanJ]

We're now at 130 pages with really nothing new on the subject.

I'm "unsubscribing".... keeps down my incoming e-mail.

Maybe when there's something really new, there will be another thread.

CJ

[Basil]

made his final flight for BA yesterday.

BA hero Peter Burkill takes off - mirror.co.uk (http://www.mirror.co.uk/news/top-stories/2009/08/30/ba-hero-takes-off-115875-21634360/)

fire trucks sprayed it with water - a traditional send-off for retiring pilots.
I don't think so - unless they're on fire.

Apologies for the source :O
Pity they couldn't find a library pic of a 777.

[keel beam]

On fire? Just for clarity.

[overstress]

Basil, you're mistaken, this does happen, I've witnessed it a few times.... how can you make such statements without knowledge of the facts...

[Algy]

I landed at Singapore in a BA 744 and on shutdown the FO came on the PA and announced that the captain had just that minute told him that it was his (the captain's) final flight as he was retiring and would be returning to London as pax. Perhaps we'd like to congratulate him. Which we did.

I supose there's an argument that that's the professional, albeit boring, way to do it. A bit like the RAF not allowing studes to make their final sortie on a course solo.

[M.Mouse]

Were talking about two fire trucks forming an arch of water that falls just like rain. Aircraft fly in rain all the time, it's not unprofessional.

Not unprofessional but totally naff in my book.

[bizdev]

I was a passenger on a United B777 flight from LHR to Chicago a couple of years ago when, on landing at Chicago, the Captain came on the PA to advise passengers not to be alarmed at the sight of fire tenders spraying an arc over the aircraft as it passed - we were not on fire! It was a 'traditional' send off for the Captains last flight. A nice touch I thought.:)

[JW411]

They tried to do this to me on my last commercial flight but the OAT was well below zero and the aircraft was on a quick turnround! Fortunately the firemen were persuaded to desist and common sense prevailed.

[manrow]

This thread originally was all about an aircraft incident not about retiring captains?

:ugh:

[Basil]

It is NOT a traditional send off.
It MAY be done but I know many retired pilots who were not washed out, most because they didn't make a big deal of their retirement.

overstress,
I've witnessed it a few times
Quite.

manrow,
this refers to the pilot commanding the 777 on the day of the accident.
Edited to add: and probably more interesting than some of the rubbish spouted on this thread.

[misd-agin]

Basil,

It's a common send off in the U.S.

Anothet 'touch' in the U.S. is to get a transponder code that has a special significance to the retiring pilot.

[Basil]

misd-agin,
Thank you for the info re the US.
This was, of course, at a UK airport and is not at all a common sight here.

[Glamgirl]

Normally I wouldn't post here, but just wanted to make you all aware that the "send off" had nothing to do with Captain Pete. He knew nothing about it until it happened.

I'll run back to where I belong now...

Gg

[Khaosai]

Hi,

dont know Peter but would like to wish him well in the future, wherever that may take him.

Rgds.

[Val d'Isere]

It hasn't yet occured to anyone to ask why someone would take redundancy from a well paid job at age 45, a year after being involved in a major incident, with causes as yet unreported. I haven't read much of the thread, so I'm assuming the causes are unknown.

Must also have a severe effect on pension, so why do it?

Other forces at work?

I'll let you all get back to discussing more important stuff, like firemen spraying aeroplanes with water.

Bizzare old place, pprune, unless it's me.

[Discorde]

Stansted 13 June 2008

A manager kindly arranged this for me on my last flight - it was a complete surprise.

http://steemrok.com/other/Water%20arch%20sm.jpg

There is no truth in the rumour that the RFF was called out in case I messed up my last landing.

[Will Fraser]

Congratulations, Captain. Is that the bird that took a bird in #2?

[Discorde]

Our ship was GBYAL, but I don't recall the reggie of the 757 that gave that bird a very severe headache.

It was quite an emotional moment - and strange too. Under the arch it was like taxying through a waterfall & we lost sight of the centreline for a few seconds, prompting the thought: 'Great, my last flight & I'll probably end on the grass!'

[Carnage Matey!]

It hasn't yet occured to anyone to ask why someone would take redundancy from a well paid job at age 45, a year after being involved in a major incident, with causes as yet unreported. I haven't read much of the thread, so I'm assuming the causes are unknown.

No it hasn't, because everyone else has read the thread and thus knows the causes.

[brs planespotter]

having just read the article referrinng too capt.burkills last flight before taking voluntary redundancy at the age of just 44, i was wondering would he have a problem getting a captains role in another carrier.?best of luck too him:ok:

[Will Fraser]

Relative to the Captain's personal decisions, I suggest it is private, and in a civil forum would remain so. Sullenberger has wandered the public domain, so an easy answer would be any carrier would be only too happy to hire Sully, bridge his seniority, and amplify his take home remuneration.

[Old Engineer]

Just wanted to add a comment that (in my opinion) the test procedure for icing that was set up to replicate in some way the combination of limiting permissible conditions was the best way to go. It may be true that it went a little beyond the actual conditions (as they are thought to be known). But it is well to consider what can happen.

I read the test reports carefully; they seemed well thought out. The only thing which caught my eye was that it had never occurred to me that the fuel piping and heat exchanger could be such an efficient scavenger of small amounts of water from the fuel.

One thing I saw way back was a Boeing memo concerning the use of the 3-degree Centigrade safety margin in using the stagnation* temperature of the outside air as the limiting low temperature of the wing interior.

*A term from thermodynamics; yes, I know a different term is usually used here. (a senior moment that I cannot recall it).

Anyway, 3C margin is a round number: 5 degrees in Fahrenheit as we mostly used to use. That margin goes back a long way-- at least to before the mid-60's and the days of the first commercial jet-- I researched that at the time. Interestingly, in the Boeing memo the justification for its continued use was that it had been used for a long time without any problems (or words to that effect). The memo was a quite frank, thorough and informed discussion of the issues surrounding fuel temperature, written before this incident. It was an informative memo of the sort that is so seldom seen in engineering any more. I was going to mention it and post a link to it, but when I did so, it had been removed (or moved).

The moral of this is, I think, that there are things in engineering that we do not fully understand (or lack the capability to deal with using practical mathematics), and so need now to increase our margins in this area.

OE

[phil gollin]

I fully accept that if there are suspicions raised of peculiar behaviour in the icing behaviour of fuel it should be investigated, and not for just one engine/aircraft set-up, but for all.

However, the present information is based on an unrepresentative fuel/water mix and hence can only be indicative of a possible problem. Only when either the icing problem is found to occur with a properly representative set-up OR when a suitable explanation for a different fuel/water mixture is found can any reliance be placed on thetest results.

The false start given by various non-AAIB press releases is irresponsible.

.

[Stoic]

OFTEN WHEN TRYING TO DETERMINE WHY SOMETHING WENT WRONG . . . . I try to see what Civil Air Regulations said about it. In this case it is CAR 4b - section 435(b) . . . I was trying to figure out why the fuel filter iced-up on the BA 777 Glider at Heathrow. I found it. this subparagraph said . . . . [(d) Provision shall be made to maintain automatically the fuel flow when ice-clogging of the filter occurs, unless means are incorporated in the fuel system to prevent the accumulation of ice particles on the filter.]

This Standard missed the transition from CAR 4b to FAR Part 25 or Part 33 - Engines. The B-777 has a fuel heater but it merely requires a certain temperature. Too bad we didn't stay with the automatic Bypass feature!

JIM

[sooty655]

Too bad you haven't been reading the thread. :*

If you had, you would realise the problem wasn't in the filter. :ugh:

Sooty

[pls8xx]

Well, I’ve followed the thread from the start. In my opinion, the current theory is not compatible with the known parameters of the flight. The mystery of what really happened to BA038 continues.

[bearfoil]

I am basically a lurker, but I've read the thread fully, and see a loophole for stoic. The FOHE is not labelled as a filter, filtering is simply not its intended function. Nominally, its blockage was caused by trapping ice at the tube sheet. There is even a bypass, but for the oil, not the fuel, and that through an air cooled matrix.

Technically, it did 'filter' the fuel. Additionally, it is not intended as a fuel heater, but does that as well, though 'poorly'.

with respect,
bear

[DERG]

Ok I have read thru most of this thread and I find it very disturbing why the reason for this failure cannot be found. In this year of 2009 I would expect the science community to have some ability to determine when a liquid will become a solid.

Have I missed something really simple here? Could it be that some players involved do not want to find the truth?

Now I have to admit that I am well known social dyslexic who often cannot see the motives that confound the human race to self destruct....

But hell...I just cannot see why this big modern airplane suffered from something as simple as fuel coagulation on descent. Did we not all learn to apply CARB HEAT....jeez!

[Dont Hang Up]

Ok I have read thru most of this thread and I find it very disturbing why the reason for this failure cannot be found. In this year of 2009 I would expect the science community to have some ability to determine when a liquid will become a solid.



DERG

If you had really read this thread as you claim, and taken on board some very erudite input from fuel chemists and engine system engineers, then you would have realised that the "simple" issue is extremely complex.

[DERG]

This is not a difficult problem to solve and I am sure that many realize this.

The complexity is in the mind and is more to do with social science than hard science.

[bearfoil]

DERG


I assure you personally your cryptic reference has been broached, ad nauseum. If not, surprise us all, as commercial interests versus safety and technological considerations are well covered.

[pls8xx]

In a way, I'm with DERG on this. Time to call in ye old pump engineer. Tell to bring his cavitation check list. Go down it item by item. One of them hasn't been looked at hard.

[bearfoil]

Generally speaking, if you have something to add, add it. Hide and seek is for children.

[pls8xx]

bearfoil said:
Generally speaking, if you have something to add, add it. Hide and seek is for children.

I did. Over a year ago. In detail.

[DERG]

Heat the fuel lines, make sure the pumps don't cavitate, condition the fuel as necessary, and insulate/heat the tanks AND make sure the software/hardware to monitor this works...as in "able to talk to each other"..maybe even developed as one unit!!

I bet $50k that somewhere there is a memo to the same sitting in a desk somewhere..... It is a sad reflection on humanity that problems like this in times of war are solved quickly.

[Dont Hang Up]

DERG, I am not sure I am following you here.

First you suggest the problem is not identified...


I find it very disturbing why the reason for this failure cannot be found.


Then start suggesting solutions relating to fuel ice!

As I understand it, the AAIB identified fuel ice as the 'most probable' cause and solutions are being worked upon as we speak, with modified SOP in the interim. So your issue is?

Incidentally, you suggest to...

make sure the pumps don't cavitate


I would suggest that cavitation was more of a symptom that a cause. And dare I even suggest it was an important clue.

[Bang Bus]

It has been some time now since a BA 777 arrived just short of the runway in London, and after the company announced there would be a report out in 30 days (after the incident) all has gone quiet, I do live under a rock, but has anyone else heard anything??

[boeing boeing.. gone]

You must live under a rock!!! There is a large thread relating to this incident!! The roll back was caused by a build up of ice in the fuel heat exchange. The plane had gone through some extremely cold air on it's route to lhr. RR has reworked the plate exchange now I believe. The plane was wrote off.:sad:

[wjsherriff]

I did not know it was on the autopilot all the way! It was!, until it reached 108 Kts! Obviously the crew was never trained too utilize the Aux. Power available in the leading edge form of the wing in a dive attitude! Why is everyone flying around on the dumb auto pilot? Where is the control feel! First indicaton of power reduction, nose over into required dive attitude to maintain flying speed, increase dive angle to increase system kinetic energy. Over the fence, flare into a level flight attitude (in ground effect) hold level flight attitude while the aircraft disipates excess kinetic energy and settles into ground contact. Get back to your basic flying skills, dont trust a dumb auto-pilot that will lead you right down to a critical108kts airspeed!

[phil gollin]

No, that is a possibility which has only been indicated by unrepresentative tests.

There is no present solution, and it would seem that any solution (assuming the basic conditions were as stated in the two interim reports) will involve new behaviour of fuel/water mixtures and a re-examination of ALL existing designs, not just the BA038 airframe/engine combination.

[Twitcher]

I see that audio/video captured live at the incident has appeared. I Assume it is new as I have not seen it before? British Airways flight 038 traffic control video, 17 Jan 2008 - Wikileaks (http://wikileaks.org/wiki/British_Airways_flight_038_crash_landing_suppressed_aircraft _traffic_control_video%2C_17_Jan_2008)

[lomapaseo]

Twitcher

Is it Virus free and has it been validated as genuine?

[Captain Airclues]

lomapaseo

Norton didn't find anything wrong with it. It sounds pretty genuine to me.

Here is a direct link to the tape;

http://88.80.16.63/leak/ba-038-air-traffic-control-tape.wmv

[Oblivian]

It is confirmed by flight global as genuine recording.

Audio record captures orderly BA 777 crash response (http://www.flightglobal.com/articles/2009/12/04/335843/audio-record-captures-orderly-ba-777-crash-response.html)

[HEATHROW DIRECTOR]

Thankfully, the clip has been erased from another forum on here.. Publishing it almost certainly contravenes the WT Act unless it is published with proper authority.

[Fargoo]

HD it's on the Flight Global website as per the link above.

[HEATHROW DIRECTOR]

Fargoo... That doesn't mean it should appear on here too! Would you like it if you were involved in a major incident and had your words spread all over??

[Rainboe]

Maybe it shouldn't be on, and maybe I shouldn't have listened, but I did. I have to say the ATC was brilliant and how very cool and efficiently it was handled by all involved give there was no warning at all.

[bearfoil]

As heartwarming as the response by all was, it only underscores the severity of the problem, and as such, without reflection, deflects directed comment, as it were. In other words, it is off thread.

Likewise the 'Heroism' of the crew. Noted, on other threads.

This problem has not gone away, not as it would be framed openly in the industry anyway, and the 'fix' is a palliative, a poor one.

bear

[atakacs]

Maybe it shouldn't be on, and maybe I shouldn't have listened, but I did. I have to say the ATC was brilliant and how very cool and efficiently it was handled by all involved give there was no warning at all.

absolutely... to be honest they certainly deserve some sort of medal :E

[Roffa]

HD et al,

It was produced by NATS for internal use, someone needs a seriously hefty kick up the jacksy for leaking it out.

[Fargoo]

Fargoo... That doesn't mean it should appear on here too! Would you like it if you were involved in a major incident and had your words spread all over??

Excuse me!

What's with the attitude? I was just letting you know it's on the Flight Global site too. No need to have a go :ugh:

A little respect for your fellow forum users goes a long way :ok:

[Rainboe]

It was produced by NATS for internal use, someone needs a seriously hefty kick up the jacksy for leaking it out.
Well that's as maybe, how dare people abroad not take note of the UK Wireless and Telegraphy Act 19XX (Yawn)! We do live in the internet age, though, and accessing this stuff from abroad where the UK Wireless and Telegraphy Act 19XX (Yawn) doesn't really have much clout. This is a global village now, and we are all villagers. Unless MI5, MI6, in fact MI7-25 are going to monitor what we download and send suits to beat me up, we might as well learn to accept government imposed censorship is becoming a tad difficile!

[Roffa]

It's nothing to do with the WT act, I couldn't give a fig about that.

The fact does remain though that it was an internal NATS production, produced by and for NATS, ©NATS and to the best of my knowledge was never intended to be released outside of NATS. The fact also that it is not the full article but a part of it also suggests it has been removed surreptitiously.

I hope NATS are able to track who had access to it and find out who leaked because NATS has a lot of training material such as this (though not always as dramatic!) containing real r/t and radar recordings of incidents and I don't want to think that I or my colleagues are in store for more stuff escaping into the public domain.

The flight deckers round here might not be too impressed if more escapes either because much of it doesn't reflect particularly well...

[L337]

The flight deckers round here might not be too impressed if more escapes either because much of it doesn't reflect particularly well...

It is nice to know that perfection is alive and well in NATS.

However, I was surprised to find your observations here on the BA38 thread.

[Roffa]

Perfection is not alive and well in NATS.

The point is that these replays are produced for training purposes so that lessons can be learnt from them. They are not meant to be put on public view where they can be misunderstood and misconstrued as would be bound to happen.

You only have to look at much at what is written on this board to know that that would be a good road to go down.

[M.Mouse]

What is there within the piece concerned that could be misconstrued? The controller sounded under enormous pressure but seemed to do all that was required clearly and efficiently.

The captain of the BA38 used the wrong call sign and transmitted his evacuation command to the tower instead of the cabin, demonstrating how shell shocked he was.

Apart from that a slightly chilling but interesting insight into a very public accident with little that could be misconstrued.

[TeachMe]

Just saw the video, and it SHOULD be made available if for no other reason to show how professional ATC was and hence to instill a touch of confidence into people. There is is too much negative stuff published that this kind of positive stuff needs to get out also.

[Sallyann1234]

The leaking of such an internal document was indeed unfortunate, but probably inevitable because of the considerable interest within the industry and indeed from the wider public. I personally found it fascinating and played it several times.

It's possible that the video may show certain emergency procedures that are best not revealed, or that being an extract from a longer video it may be giving a misleading impression of the whole event. But it is likely that if a sanitised version had already been published to show how well the situation was dealt with by ATC, the leak of this particular document would not have occurred.

[atakacs]

I would say that in this specific case the leak actually puts a very positive spin on the quality of the ATC / airport crew response. Not as excuse not to follow regulations but nice none the less.

[eglnyt]

I would say that in this specific case the leak actually puts a very positive spin on the quality of the ATC / airport crew response.

it is likely that if a sanitised version had already been published to show how well the situation was dealt with by ATC, the leak of this particular document would not have occurred.

As Roffa has tried to point out once you move away from a principle of not publishing anything and decide to publish positive things it is only a small step to the point where you have to publish everything and we'll quickly reach that point. Once that happens you'll find that when the outcome is not so positive the clip will be live on 24 hour news with the usual group of self appointed aviation experts passing their unqualified judgement on why somebody screwed up. Do you really want that ?

[lomapaseo]

Were there any lessons learned from the actual ATC content? That's of more interest to me than how/why it was leaked.

[night_flight99]

TwoOneFour stated:


"Is the "public" somehow a different species? Seems like there's a weird assumption that people in aviation have a different kind of brain, which the rest of us don't possess. Good job we're only employed as neurosurgeons, structural engineers, nuclear scientists and stuff..."

I don't know which of those professions you are employed in but a lot of us on here are are professional pilots. I'll bet you a £ to a bag of the proverbial that you won't find too many of us with the arrogance to post on any forums that exist for neurosurgeons, structural engineers, nuclear scientists etc about the best way to use information from the many incidents or accidents in those industries.

Aviation has a proud history of learning from the inevitable mistakes and errors that occur and there are good reasons why the information derived from those events are treated in the way that they are. I can assure you that merely serving your voyeuristic interest would not be high amongst them.

[violator]

Rainboe,

Well that's as maybe, how dare people abroad not take note of the UK Wireless and Telegraphy Act 19XX (Yawn)! We do live in the internet age, though, and accessing this stuff from abroad where the UK Wireless and Telegraphy Act 19XX (Yawn) doesn't really have much clout. This is a global village now, and we are all villagers. Unless MI5, MI6, in fact MI7-25 are going to monitor what we download and send suits to beat me up, we might as well learn to accept government imposed censorship is becoming a tad difficile!I have no intention of such things filming me. Another enormous expense for the airlines (anything for an aeroplane is mind-bogglingly expensive) which will have to be recouped from the passengers (who are already being caned to death for tax revenues by all sorts of rapidly increasing taxes).

I can think of few accidents where a camera image would have been of any use whatsoever. Accidents like the Turkish 737 into Amsterdam would have revealed nothing new to a camera. Pilots have a right to privacy in their workplace.http://www.pprune.org/tech-log/386955-cvr-fdr-vcr-post5158892.html?highlight=recorder#post5158892

ATC tapes are a free-for-all but flight deck recorders are a personal privacy issue? :\

[bearfoil]

Never was about privacy, that is a red herring. The airlines, as public carriage, are regulated by a public authority whose mission is the acquisition and maintenance of safe transport. The devices are strictly controlled, but ultimately are under the control of the authorities. Any pilot who is annoyed at 'intrusive devices' is in la la land. If it's embarrassing or unsafe, don't do it.

[Green-dot]

Listening to the ATC tape, it illustrates how precious little time the crew really had between landing clearance and landing short. Less than 30 seconds (closer to 20 seconds if the 7 seconds between roll back of RH and LH engine are taken into account as well). Apparently everything was still working as advertised when confirming the landing clearance with a confident, routine voice.

[funster]

I totally don't understand why the recordings would be 'private'. It paints all involved in a professional manner who when put to the test handled themselves very well. Now it's on You Tube (search BA038) it certainly won't be going away anytime soon.

[Mmmayday38]

I discovered (courtesy of this thread) over the weekend that this DVD clip had been leaked.

I have explained in a blog on my website how I came about being in possession of the clip, why it went on my website in the first place and was then removed and then the reason behind ‘Speedbird 95’ and the evacuation command. I’m not going to post it on here as there will be some who are not interested.

I am not allowed to give you the direct link to the website as it can be misconstrued as advertising, but if you want to have a look it won’t take you long to figure out if you put my first and surname together with a .com after!

[Twitcher]

I see Youtube has started deleting the clip from the site quoting This video is no longer available due to a copyright claim by NATS Limited though it is on there several times so it will continually need deleting.

[EGLD]

Mmmayday38,

I'm only an occasional visitor of these forums but was drawn back here by the recent appearance of this ATC clip on the web.

I've vaguely followed your story since the accident and was, like many, surprised at what you and your family had to suffer in the aftermath of this incredible event. Like someone posted elsewhere, there is an inexplicable difference in the cultures between here and the US when you look at how our scumbag press behaved towards you and how the US rightly supported that guy.

Anyway, I'm just a passenger, and watching that clip gave me an insight into what happened that day and was a reminder of what an incredible achievement it was by your crew to deliver everyone safely back to their families. Reading your posts here it again leaves a very sour taste in the mouth as to how you have been treated and what you vaguely hint at with BA.

You are a credit to your profession and your family should be immensely proud of you. I wish you the very best in whatever you end up doing for the rest of your life.

[Rainboe]

ATC tapes are a free-for-all but flight deck recorders are a personal privacy issue?
Absolutely! ATC tapes are a record of communication between ATC and outside agencies. Cockpit Voice Recorders similarly. CVR transcripts, indeed even CVR recordings end up in the public domain. What makes ATC recordings so special you have to resort to this absurd Inspector Clouseau secrecy? If the Hudson River recordings are freely released under 'Freedom of Information', then I suggest we give up this daft attempt at cloaking everything official in the UK- it just won't wash in the internet age.

You picked my quote about putting cameras on flight decks. I have seen the effect of cameras filming there- use...er...lesss! Total waste of time and money. You see very, very little. Yet they are a big invasion of privacy (as well as a handy place to hang my jacket). So why not put cameras on ATC controllers as well then if pilots are supposed to have them? Shots of controllers talking to Speedbird 287 whilst scratching their arses and blowing their noses and looking at it will go down well with the public!

[757flyer]

ahhhh rainboe! you are alive!! see you have kept your gob shut on the BMI / Aerlingus threads lately! whats the matter???? may loose your job to BMI boys??? market forces old boy dont you know !

sorry to bust in on this thread but I had to throw a bit of mud at the gobby git ;-)

[Brian Abraham]

I think the previous post has proved why this site has gone downhill in recent years, misguided 17 year old schoolboys spouting cr@p about sums it up! Rather read Rainboe any day. ;)

[bluepilot]

I personally have no problem with the publication of tapes etc, in the case of fatal accidents then discretion should be used giving due respect to deseased and relatives.

With regard to Rainboe, perhaps Brian Abraham you havent seen the posts he has made re-astraeus and aer lingus contract, he has certainly stirred things up!

[poorjohn]

It's not clear from the recent posts whether a link to that atc audio/video is welcome or disallowed on this site. If allowed, here's one in Sweden that's likely to remain available due to their attitudes about freedom of information: http://88.80.16.63/leak/ba-038-air-traffic-control-tape.wmv. If not, mods will surely deal with it. My apologies for not understanding, in that case.

In general wikileaks dot org is a good place to find such links.

More or less aside, I'm quite surprised that it's being so aggressively suppressed by the authorities, and also that at least a few voices here have expressed support for that position.

The nearest thing to personal sensitivities would be the captain's oopsie in giving the evac order, and besides forgiving him for being a mite excited moments after having crashed a 777 and survived, we know from him specifically that he supported the release.

[Rainboe]

I won't endorse hijacking of other threads by plonkers by indulging in off-track discussion! Some people definitely have ADD (attention deficit disorder)!

[violator]

Rainboe,

Absolutely! ATC tapes are a record of communication between ATC and outside agencies. Cockpit Voice Recorders similarly. CVR transcripts, indeed even CVR recordings end up in the public domain. What makes ATC recordings so special you have to resort to this absurd Inspector Clouseau secrecy? If the Hudson River recordings are freely released under 'Freedom of Information', then I suggest we give up this daft attempt at cloaking everything official in the UK- it just won't wash in the internet age.But you miss my point. You seemed against CVRs being made public and indeed confirmed it in your first word of this reply. I don't see the difference between CVR recordings and ATC recordings in a crash. Whilst CVRs may capture the last desperate seconds of a fatal crash, this ATC tape records the emotional (albeit professional) response of people to witnessing a large commercial aircraft - which they are in a sense responsible for - crashing in front of them. By all means suggest that CVR recordings be private, but the same must apply to ATC recordings.

One big problem with realsing ATC and CVR tapes (after the ethical ones) is the issue of context. I'm sure you'd be the first person to attack the press for an ill-informed, ignorant and out-of-context analysis of the recordings. In fact you could imagine some tabloids spinning this recording to show a captain who not only got the callsign wrong, but was so incompetent that he transmitted the evacuation order over VHF.

You picked my quote about putting cameras on flight decks. I have seen the effect of cameras filming there- use...er...lesss! Total waste of time and money. You see very, very little. Yet they are a big invasion of privacy (as well as a handy place to hang my jacket). So why not put cameras on ATC controllers as well then if pilots are supposed to have them? Shots of controllers talking to Speedbird 287 whilst scratching their arses and blowing their noses and looking at it will go down well with the public!You miss my point, plus there's no need for such an agressive tone. I never said that flight deck cameras are required as a result of this crash, I was using your quote to suggest that you think recording the flight deck is an invasion of privacy, which you've confirmed. I was highlighting your hypocrisy between ATC recordings and flight deck recordings.

If flight deck cameras being used for internal crash investigation purposes are an invasion of privacy, then surely ATC tapes released to the public is a worse invasion of privacy? I don't follow your logic - ATC have as much right to privacy as flight crew.

[Rainboe]

What hypocrisy are you talking about? You've steered this discussion off line. Flight deck CVR tapes are released to the public, why not ATC tapes? That same public has funded ATC and paid the NATs staff- I'm afraid the public 'has a right' to hear the results of its investment! If you are going to advcate cameras on the flight deck, then let's do the job properly and have cameras on ATC controllers so we can ensure that no Uberlingens happen again with controllers left alone manning the shop. Good idea, eh?

As far as I am concerned, my CVR recordings, which were meant to be totally private and only made use of if no pilots survived to tell the tale, can be subpoenad and published for the public's predilection. It stops there. I will not have a camera recording 'my office', including recording what could be the final moments of the pilots, for the greater entertainment of the guffawing public, because we all know such recordings will not remain private (as we were assured in the industry the CVR recordings would be- what became of that then?).

I seriously resent your remark about 'incompetence'. You are indeed a fool. For a crew flying perfectly normally then crash a few seconds later under very stressful circumstances- you don't understand what you are talking about and I suggest you shut it! You are obviously a desk bound engineer of some sort and have no operational literacy to make such a sweeping (and cruel) idiotic statement. Not even ATC. What do you know that you can step in here with such blundering comments?

[violator]

Flight deck CVR tapes are released to the public, why not ATC tapes?What? I can't think of a CVR recording from a UK crash that's been released. I can't think of a Western one released or leaked since the 80s. Do you support the CVR recording of BAW038 being released to the public?

As far as I am concerned, my CVR recordings, which were meant to be totally private and only made use of if no pilots survived to tell the tale, can be subpoenad and published for the public's predilection. It stops there. I will not have a camera recording 'my office', including recording what could be the final moments of the pilots, for the greater entertainment of the guffawing public, because we all know such recordings will not remain private (as we were assured in the industry the CVR recordings would be- what became of that then?).The AAIB/CAA principle certainly is that CVR recordings won't be released, it might even be law. You can't have on the one hand your complaints about the public listening and watching in on what you're doing, and on the other hand your seeming delight at being able to hear what ATC are doing during a crash.

I seriously resent your remark about 'incompetence'. You are indeed a fool. For a crew flying perfectly normally then crash a few seconds later under very stressful circumstances- you don't understand what you are talking about and I suggest you shut it!I said:

One big problem with realsing ATC and CVR tapes (after the ethical ones) is the issue of context. I'm sure you'd be the first person to attack the press for an ill-informed, ignorant and out-of-context analysis of the recordings. In fact you could imagine some tabloids spinning this recording to show a captain who not only got the callsign wrong, but was so incompetent that he transmitted the evacuation order over VHF.I was clearly talking about tabloid spin!

Let me rephrase, the tabloids could quite easily suggest that the flight crew of BAW038 made mistakes, based upon a layperson's interpretation of the ATC tape. If such a suggestion were made in the press I predict that you would be one of the first to (rightly) condemn them. This alone is a strong argument to keep private ATC tapes.

This is the danger of releasing tapes to the public without context, be they CVR tapes or ATC tapes. I see no distinction between them, for the reasons I've outlined above; neither should be released.

Rainboe, you've twice mis-read my post and responded agressively where no agression was called for. I suggest you take time to read posts properly before posting in anger.

[Rainboe]

Violator, I don't like conducting technical or industry discussions with someone who could well be a pizza delivery person Walter Mitty character pretending to be someone in the industry. We get a lot of those here. Many people have tried to get this section closed to 'unknowns', and I have to say I support it, but it has been judged to be impractical. Your profile is peculiarly empty, you discussion history limited. If you are such and expert you are qualified to take a leading position here and come out with some of the adamant and critical statements you have, opening up a bit on your expertise is definitely in order. Otherwise, I really don't like professional criticism coming from an anonymous 'nobody' and your remarks are ignored. What a dreadful thing you said.

[Sir Niall Dementia]

I've had to sit and listen to a CVR with the gentlemen from the AAIB following the worst day of my flying career. In the UK the CVR remains the property of the crew (under copyright laws believe it or not) We heard the whole tape, including the scurrilous conversations we had been having about management during the cruise. The AAIB asked P2 and myself if they could use certain parts of the transcript alongside DFDR data in the final report and we had to sign that we were happy for that. If either of us had a doubt then the CVR material would not be used.

If that CVR tape had become public would it have done anything other than provide tabloid titilation, and cause utter fury in the people we had been discussing as well as damaging the image of the company. No-one other than another pilot, or aviation specialist would have understood what was going on during the last few minutes of flight.

I bless the fact that CVR data in this country is private. The AAIB tend to use it, mostly to back up the pilots' initial statements, and to pick up what the pilots may have missed in their shocked state. We were treated with kindness and humour by the AAIB and our fears about anything private getting out were instantly allayed. IF CVRs were in the public domain I would have great concerns about how the data would be treated by the media.

[violator]

Rainboe,

Violator, I don't like conducting technical or industry discussions with someone who could well be a pizza delivery person Walter Mitty character pretending to be someone in the industry. We get a lot of those here. Many people have tried to get this section closed to 'unknowns', and I have to say I support it, but it has been judged to be impractical. Your profile is peculiarly empty, you discussion history limited. If you are such and expert you are qualified to take a leading position here and come out with some of the adamant and critical statements you have, opening up a bit on your expertise is definitely in order. Otherwise, I really don't like professional criticism coming from an anonymous 'nobody' and your remarks are ignored. What a dreadful thing you said.

What are you on about? Instead of answering any of my points you launch into another bizarre agressive rant. I never said any dreadful things, have you still not understood my point?

I work for an OEM, I'm not going to make my personal details public.


I bless the fact that CVR data in this country is private. The AAIB tend to use it, mostly to back up the pilots' initial statements, and to pick up what the pilots may have missed in their shocked state. We were treated with kindness and humour by the AAIB and our fears about anything private getting out were instantly allayed. IF CVRs were in the public domain I would have great concerns about how the data would be treated by the media.

I'd suggest the same is also valid for ATC tapes.

[Joshilini]

Off Topic:
This is what I truly despise about PPRuNe. In practically every single 'rumour & news' thread, some moron always posts something utterly unrelated to the main topic which results in other morons discussing it and thus, irrelevant discussions are created. Why are people discussing the legal issues with CVR tapes? Is this thread about that? No. So shut the hell up and go discuss this somewhere else. This thread is about the BA777 crash in January 2008 (yes, nothing gets past me), so only post relevant messages about the topic in hand. Yapping on about something so unimportant and unnecessary to the main topic is just ruining the discussion.

On Topic:
I have listened to the ATC tape and it appears that two mistakes were made by captain Burkill (which he has admitted and explained in his blog). Speedbird 95 was his callsign for his next flight (instead of his current flight's callsign, Speedbird 38) and his evacuation announcement to ATC (instead of transmitting it over the cabin PA system). Though both mistakes didn't really make any difference to the outcome of this accident, these were the only mistakes by the crew that we know of so far but we should remember the enormous stresses that they were put under and how little time they had to react to the dreadful situation that they ended up in.

Splendid job to the captain (for retracting the flaps), the first officer (for preventing a stall), the cabin crew (for a speedy evacuation), the air traffic controller AND the emergency services.

I think the aftermath could have been handled so much better though by BA. Why were the crew placed into the media spotlight shortly after the accident? I think the decision to do this had a slightly negative effect on the crew and BA overall. Look at how US Airways managed captain Sullenberger and the crew of flight 1549 after the accident last January. That's possibly why captain Sullenberger is highly regarded as a key speaker for the aviation industry now by his fellow workers.

EDIT: Haha, oh yes! Thanks Cav (I always get the number of years between Speedbird and Cactus mixed up).

[Cavallier]

Totally agree with you Joshilini, but something has got past you and that is the date. 2008 not 2007!


The Cav ;)

[misd-agin]

Joshilini - "Splendid job to the captain (for retracting the flaps), the first officer (for preventing a stall),"

I thought the general rule is to let the investigators decide the facts before annointing villians or heroes?

[bearfoil]

Similarly, I cannot judge Colgan BUF, nor BA038. "Retract Flaps" G/B?
Causing, preventing Stall? Raising Stall Speed @ Stall Speed?

bear

[S.F.L.Y]

Until what speed was the AP trying to follow the GP (leading 300m beyond threshold)?

[cwatters]

Let me rephrase, the tabloids could quite easily suggest that the flight crew of BAW038 made mistakes, based upon a layperson's interpretation of the ATC tape. If such a suggestion were made in the press I predict that you would be one of the first to (rightly) condemn them. This alone is a strong argument to keep private ATC tapes.

Yes just look how the media "reinterpreted" the climate data/emails when that was "released".

[misd-agin]

S.F.L.Y. - the a/c was at Vref 135 kts, on a/p, on g/s, when the engines reduced to a power setting less than demanded but slightly above idle.

Obviously the a/c slowed. At approx. 115 kts the flaps were retracted from 30 to 25.

At approx. 105 kts, with no more airspeed to sacrifice to stay on g/s, the a/c started to sink below g/s and the a/p disconnected. Speed stabilized at approx. 100-105 kts.

The FDR readout is on page 6 of this report -

http://www.aaib.gov.uk/cms_resources.cfm?file=/G-YMMM%20Interim%20Report.pdf

[Joshilini]

@ misd-agin...

Read the preliminary report. It states that the commander adjusted the flap setting.

[S.F.L.Y]

@ misd-agin...

Read the preliminary report. It states that the commander adjusted the flap setting.

So what? In the same time the aircraft was still under AP aiming at a point far beyond the threshold until it stalled. I never thought that the flap handle could be more important than holding the control column and checking the airspeed when the AP is pulling-up with no thrust.

[WojtekSz]

S.F.L.Y - you must have missed the information from both the Preliminary Report and flying basics that reducing the flaps was aimed at reducing the drag when the power become lost.
You have correctly noticed that the speed control was critical and reducing flaps was aimed at maintaining the speed and the lift required to keep a/c in the air. This helped to keep the a/c aloft just for a few second longer but those additional seconds had tremendous influence on the final vertical speed.
The plane was flying and not falling down practically until the end. Final descent rate was about 1400fpm but if the plane kept flying just 3 sec longer it could have been at least 2x bigger with fatal consequences. See the diagram on page 6. Check basic physics.

[S.F.L.Y]

Thanks for the information on flight physics. Since you're in the knowledge of how iron birds flies you should know that when you increase the attitude close to the stall speed the drag also increases very quickly (just look at a polar curve). So why reducing drag with flaps when the AP increases it?

You mentioned that the flaps were retracted to reduce the drag because speed control was critical. If this speed control was so critical why letting the AP spoiling it by increasing pitch (and drag) aiming at a point far beyond the threshold? If one thing was out of control during this landing it's obviously speed.

The shortest way is the straight line, flying above it at pre-stall speed is certainly a waste of energy which can't be balanced by flaps inputs.

[bearfoil]

With S.F.L.Y. here. No one can say if Captain Burkill made the wrong move. Raising flaps while short at low speed and high AoA is not something I would do. Dumping drag is also dumping lift, and the first thing that big bird is going to do with a cleaner wing is sink. If the nose is not lowered, and the Stall Speed is elevated by cleaning the wing, well, never Stall. Ever. Turkish Stalled and the nose occupants croaked. Then again, it may have been brilliant, I wasn't there.

bear

[misd-agin]

Joshilini - the report says the Captain retracted the flaps in an attempt to reduce drag.

The stall speed reduction from flaps 30 to flaps 25 is 2 kts. That requires a higher AOA to achieve the same amount of lift. I have no idea, and I doubt very many, if any, non Boeing test pilots know if reducing the flaps from 30 to 25 is a net reduction in total drag. I don't know the answer. I'll await the results of the investigation. However, based on the resulting AOA increase I tend to doubt that total drag was reduced.

If you have time you can test this in the sim. Set up a steady flight condition, fly Vref -20, and retract the flaps from 30 to 25. Fuel flow goes up, you're fighting more drag. Fuel flow goes down, total drag is less. I'd recommend turning level flight to increase the power, thereby making it easier to see any differences in power required.

[S.F.L.Y]

misd-agin, your statement is very correct provided the aircraft flies the same speed. In this case the AOA didn't only increase to compensate the flap reduction, but also (and mainly) because the speed dropped seriously low. Flying just before the stall speed would involve a high fuel flow increase, meaning significant increase in drag. Letting the speed drop so low while aiming too far for touch down is definitely ending in shortening the path with high Vz impact as there's no other way to get back some of the wasted energy to maintain some lift on the wings.

[misd-agin]

S.F.L.Y - I've been told L/D is slightly faster than Vref. Slowing below L/D decreases your glide distance. Doing it too early, with not enough altitude to push over and regain L/D, is only going to increase your sink rate and resulting impact.

[Joetom]

Just appears to me, crew had little time, they made some decisions, aircraft touched down with suitable pitch/roll and speeds and resulted in a great outcome on that day.

Touch down shorter could have been more of a problem with a drain of some sort I think they mentioned.

Touch down later and ramping up on runway from mud may have been more of a problem.

Hindsight is great after the events.

I still have my hat off to all the crew, well done.

[misd-agin]

Joetom - I agree, they had very little time and hindsight is 20/20. However, that doesn't mean we shouldn't investigate, and understand, what was helpful and successful and what wasn't. That is the nature of our business.

[WojtekSz]

@S.F.L.Y:

lets get the picture right:
we are flying B777 standard approach, at 500ft the speed is 135kias as needed, AP is engaged, gear down, flaps 30. Speed is getting too low so we increase the power, wait 4 sec for reaction, there is none so reduce throttles and reapply full throttles again, wait 4 sec for reaction. The a/c is now about half way down at 240ft, speed is 115kias. Pitch grew to +8deg. All this took 26 sec.

Due to lower speed the time we will stay in the air would be much shorter than this 26 sec (actually it was 17 sec). There are some buildings before we are over the threshold.

... you should know that when you increase the attitude close to the stall speed the drag also increases very quickly (just look at a polar curve). So why reducing drag with flaps when the AP increases it?Just see how the flaps 30 are viewed from a side! Gear down+flaps form a huge airbrake which takes some 30..50% engines power to keep the speed stable!.
The drag/lift difference between flaps 30 and flaps 25 is like between landing and take-off because flaps 25 may be used for take-off.


You mentioned that the flaps were retracted to reduce the drag because speed control was critical. If this speed control was so critical why letting the AP spoiling it by increasing pitch (and drag) aiming at a point far beyond the threshold? If one thing was out of control during this landing it's obviously speed.afaik AP was doing what it was supposed to do - keeping the a/c flyin to the destination. The speed was too low, no reaction to AT so the attitude had to go up. With no engines reaction to manual full throttle PF had to react whatever way was available at such limited time/circumstances.


The shortest way is the straight line, flying above it at pre-stall speed is certainly a waste of energy which can't be balanced by flaps inputs.

so there we are: at 240ft, flaps 30, 115kias with two choices: (1) fly at the a/c as is or (2) do something to reduce drag

if you know the drag difference between flaps 30+wing at appropriate attitude and flaps20+ appropriate attitude - than there is no brainer ;)

[WojtekSz]

@ misd-agin + bearfoil

dumping drag is also dumping liftabsolutely correct at speeds comfortably above Vs.
but when we are just a few knots above Vs, with the a/c slowing down - anything that keep the plain flying at above Vs has absolute priority.

[Me Myself]

Hi evryone

I haven't followed the thread for a very long time and it's grown to big to read it all.
Someone mentioned to me the Captain and the F/O had been given the sack by BA.
I have somehow a hard time believing it. Could anyone in the know confirm the fate of these 3 pilots ?
Thanks

[chrisN]

See the captain's own post no. 2657 on page 133.

From his own website, found using the hint in post 2657: it appears that he left British Airways (implying by his own wish) to pursue a speaking role talking of his experience.


Chris N.

[S.F.L.Y]

afaik AP was doing what it was supposed to do - keeping the a/c flyin to the destination.

Wrong, the AP was trying to land the aircraft hundreds of meters away from the threshold as this is where the ILS leads. Trying to maintain this path at the expense of speed wasted energy and lead to high Vz.

We know the aircraft had enough total energy to reach its actual touchdown point and we know a lot of kinetic energy has been wasted by the AP... instead of being used to reduce the impact Vz.

Why do we need to have two pilots in the cockpit if none is able to monitor and control the airspeed through primary flight controls (which doesn't include flaps)?

[S.F.L.Y]

777 pilots, is this the case? Is there no low speed protection when the aircraft has captured an ILS?

What kind of low speed protection can be designed to maintain an ILS without thrust?
Rocket boosters maybe?

[deeceethree]

On the B777, as long as the autothrottle is armed (but not necessarily being used), it should automatically activate stall protection if an ILS is being flown using the autopilot or flightdirector in G/S (glideslope) mode, but only up until 100 ft radio altitude on the approach. Thrust should be increased to maintain minimum manoevring speed (approximately the top of the amber band) or the speed set in the mode control panel speed window, whichever is greater. The EICAS message AIRSPEED LOW will be displayed if this occurs.

Obviously, in the BA038 case there was no thrust available to increase the speed.

[maynardGkeynes]

Isn't there a fuel cutoff switch in the B777 cockpit? Is it clear beyond any doubt that the crew didn't hit the switch by mistake? Would such an event be something that the "black box" would definitely have recorded? With all the exotic explanations being offered, isn't it just possible that the investigators have overlooked the obvious? Just asking....

[deeceethree]

I expect that, with no thrust available, the stick shakers would operate and the pilot would have to (be expected to?) override or disconnect the autopilot to avoid stalling. Initially at least, if left to it's own devices, I think the autoplilot would still attempt to follow the glidepath. Would it attempt to follow the glidepath until it fell out of the sky? I can't find a definite answer at the moment, sorry.

The crew did not have a switch-pigs whilst airborne - the recorded data would show that. Have you not read any of the AAIB reports? :ugh:

[maynardGkeynes]

The report talks about "uncommanded" spars activation. I was referring to a "commanded" but accidental activation of spars. But looking at the report again, they say that the spars remained opened at all times. So that's pretty definitive. However, the report does not actually state that a commanded spars activation could not go unrecorded -- it says that an uncommanded one could not go unrecorded -- but I guess they felt it was obvious that either would be recorded. Thanks for the reply.

[WojtekSz]

@S.F.L.Y:
Quote:
afaik AP was doing what it was supposed to do - keeping the a/c flyin to the destination.
Wrong, the AP was trying to land the aircraft hundreds of meters away from the threshold as this is where the ILS leads. Trying to maintain this path at the expense of speed wasted energy and lead to high Vz.
oups - i had an impression that the ILS was much more advanced and would actually lead the plane to land EXACTLY at the beginning of the runway - but who knows - maybe i was wrong ;)
or maybe you have missed something ? Maybe it is just the localizer (direction guidance) that is located at the other end of the runway?


We know the aircraft had enough total energy to reach its actual touchdown point and we know a lot of kinetic energy has been wasted by the AP... instead of being used to reduce the impact Vz. you seem to be pretty confident about this total energy but actually lets think: a/c was landing following the ILS slope, the speed and height were just right. Under normal conditions before final touchdown the engines would be giving some 50% thrust fo another 35..40 secs and this would make the a/c land exactly at the threshold as defined by ILS g/s.
So if the engines stopped some 40 secs too early this creates significant energy deficit. Exact amount of the missing energy can be calculated if needed. Just let me know if this qualitative description is not enough.
This is a little like driving your car into the garage: one do not seem to need much power to do so. But try to push your car into the garage without engine running...


Why do we need to have two pilots in the cockpit if none is able to monitor and control the airspeed through primary flight controls (which doesn't include flaps)? could you pls remind us who did pushed the thrust levers to full? Didn't the pilots try to control the airspeed with the engines first, and only when has proved unsuccessful they have turned to the whatever else existing means were available to them: reduced flaps to reduce drag and lowered the nose to stay above Vs

[suninmyeyes]

Suitcaseman,

In reply to your earlier question. If available thrust reduces, the 777 autopilot will fly the ILS glideslope until the speed reduces to just above the stall. It will then ignore the glideslope, lower the nose and descend just above stall speed. If the 038 had hit the ground in this configuration everyone would not have walked away. That statement is based on having seen it a few times in the simulator. Full up elevator, (unheard of in a 777 landing) had been applied at the appropriate time just before impact to cushion it so that many of the occupants thought on touchdown that it was just a hard landing.

The speed protection logic is the same as if you have an engine failure at high altitude in the B777 but maintain alt hold. The speed comes back to just above the stall and then the aircraft descends at that speed and ignores the engine out target speed.

[Mmmayday38]

MaynardGKeynes wrote:
"Isn't there a fuel cutoff switch in the B777 cockpit?
Is it clear beyond any doubt that the crew didn't hit the switch by mistake?
Would such an event be something that the "black box" would definitely have recorded?
With all the exotic explanations being offered, isn't it just possible that the investigators have overlooked the obvious? Just asking...."


I'm not sure if this was a question to bait me into answering...but it worked!

Simply;
Yes, there are two fuel cutoff switches in the F/D.
Yes, it is clear the crew didn't 'hit' the switch by mistake... (I did check at the time!)
Yes, it would have done.
NO, the investigators (AAIB, NTSB, Boeing, BA or the Fire Dept's pictures) couldn't have overlooked it!

Thanks for asking though.

I was about to reply to 'Suitcaseman' about his question relating to 'stall protection' on an approach; but I see that it has been answered now.

[Me Myself]

thanks a lot

[M.Mouse]

How he knows the aircraft had enough energy to reach the touchdown point without thrust I'm not sure. Maybe those rocket boosters he mentioned previously.

Retracting the flaps from 30 to 20, descending until approx 200' then flying level in ground effect and extending the flaps as the speed decays worked in the simulator enabling touchdown on the threshold of the runway.

What all that ignores is that in the simulator the event was expected, reaction to the power loss was immediate and the plan had already been formulated. The BA38 crew did not have that luxury and so really the exercise was a little academic.

It is by no means meant to imply that the crew should have done better.

[maynardGkeynes]

I'm not sure if this was a question to bait me into answering...but it worked!Definitely not intended to bait anyone, and I appreciate the reply!

[misd-agin]

suninmye - you stated - "If available thrust reduces, the 777 autopilot will fly the ILS glideslope until the speed reduces to just above the stall. It will then ignore the glideslope, lower the nose and descend just above stall speed. If the 038 had hit the ground in this configuration everyone would not have walked away. That statement is based on having seen it a few times in the simulator. Full up elevator, (unheard of in a 777 landing) had been applied at the appropriate time just before impact to cushion it so that many of the occupants thought on touchdown that it was just a hard landing."
-----------------------------------------------------------------------

Do you have an official statement that supports your position? The FDR data released by the AAIB doens't show enough data to support your statements, which is why I ask.

There is evidence of an increase in pitch attitude, and a slight decrease in speed, just prior to impact but slight changes in pitch and speed were present just prior to the last FDR data.

Also, if the a/c is being governed by low speed protection, what effect would moving the yoke, to increase AOA, have?

[S.F.L.Y]

@ WojtekSz
oups - i had an impression that the ILS was much more advanced and would actually lead the plane to land EXACTLY at the beginning of the runway - but who knows - maybe i was wrong http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/wink2.gif The ILS does not lead the aircraft to the begining of the runway but to the touchdown zone abeam which the glide path antennas are located. On the ILS you usually cross the threshold at 50 ft AGL and touch down some 300 m further.

Keeping the AP on probably means that the crew was expecting thrust to be recovered without deviating from the ILS. Disconnecting the AP and flying below GP to maintain some energy to reach the threshold at a decent Vz is most probably feasible (as in the sim) but would require immediate identification of the loss of thrust.

The OCH on an ILS is decreasing with the distance from the threshold, but gives some room to follow a "flatter" path. I was basically saying that since the acft had enough total energy to reach its actual touchdown point (in the grass) it could probably have reduced its impact Vz by saving energy in not following the GP, which seems to have been demonstrated in the simulator.

[Mmmayday38]

Hindsight is great isn't it!

I have been told by a couple of sim instructors ‘in the sandpit’ that with a few months of 'hindsight' and accumulated knowledge about this accident, a fair number of crews were 'surprised' with this scenario in the sim; and some of those that claimed to know the method to achieve the actual outcome or 'better', suddenly 'froze' in the sim. Others followed the method I had used on the day, but with hindsight were able to change the flaps earlier, and they still only achieved the same distance or worse! The majority of crews faced with this problem, crashed well short of the perimeter fence; so the people who claim to have done any better; have more forethought than me or less headwind!

It would be interesting to know if those that have “made the r/w” in the sim have used timings based from when we officially had rollback at 720ft or when we, on the day, actually realised we had a problem at 480ft. At 480ft in the sim, are pilots actually then taking the time to decide if this is a ‘fuel’ problem, an EEC problem, a windshear scenario, a double engine failure with EICAS failure…. the list is endless… or..jumping straight to the conclusion that it must be ‘rollback’, which of course was an unknown event on Jan 17th 2008!

Unfortunately for any crew, if this ever happens again (for whatever reason, but it shouldn't now anyway) will be that it is now an emergency procedure with a memory C/L, so would have to be carried out to adhere to SOPs. Will they… close the thrust levers for 10 secs to warm the FOHE or will they change the flaps or both. Two of those will be wrong according to any new SOPs…a big grey area. Pilots will naturally take some seconds to correctly identify the failure as ‘rollback’ and even then might not believe it; so to carry out this drill at low altitude will be scary. Not many pilots I know would like to close thrust levers for at least 10 secs below 400ft on an approach. The spool-up time would be too late. Please also bear in mind another real life rollback event where the crew knew of the event on the BA38; but in a relaxed state of mind in the cruise, they still took some time (in minutes) to realise this was a rollback before they reacted.

I accept that the r/w has been achieved in some sim sessions, but I am not in possession of the sim inputs for my scenario. I appreciate that some posts that make reference to making the r/w are backed up with “with the benefit of hindsight”, however, I don’t know what the settings were set to, or if the drill was only ever practiced with a “complete knowledge that there is a rollback at 480ft and what can you do to get the aircraft down” – as opposed to treating it like an unknown emergency situation ... but would you actually have wanted to take the risk of landing on the tarmac, with massive potential for a fire?

If it was always treated as an emergency situation, then, for those of you who made the r/w, I am sorry for my explanation above, but I am sure you can understand why I felt the need to explain to those non flyers the information needed when coming to a conclusion that the engines are suffering ‘rollback’ as opposed to any other emergency.

Boeing have tested this to the limits in their sim; as you might expect, so you will be able to read their results in due course when the AAIB final report is issued this year.

I, and my family, await its’ release eagerly.

[bearfoil]

Had the a/c made it to the concrete, 10,000 pounds of fuel was waiting to ignite in the ensuing spark fest. I don't see how the a/c could have made the strip had one practiced the profile for weeks. Given they made it over the fence, missed the hard stuff and no one croaked, what's to complain? Good grief. The Fuel, the fuel, boss.

bear

[Green-dot]

However, the report does not actually state that a commanded spars activation could not go unrecorded -- it says that an uncommanded one could not go unrecorded -- but I guess they felt it was obvious that either would be recorded.


Question remains, would it be recorded the moment the spars moved from their open position or would a record be made only if the spars reached their closed position? In other words, if an uncommanded partial closing of the spars had occurred which rectified itself before they reached the fully closed position, would that have been recorded? If only recorded when reaching closed position: spars take up to 15 seconds to fully close so if an anomaly lasted anything less than 15 seconds and the spars moved back to their open position, they could have restricted fuel flow considerably without having a record of it and, as reported, the spars would be found in the open postion.

[S.F.L.Y]

The question isn't to know if it was or not technically possible to make the runway. Before being limited by any technical factor the aircraft was limited by its crew's situation awareness. Appropriate actions cannot be taken before the crew realize and identify the problem The pilots were obviously very confused as they let the AP flying the aircraft at a dangerously low airspeed without taking manual control, most probably because they didn't have time to realize they should give-up on the ILS trajectory.

As a pure coincidence, the flap retraction probably caused the AP to disconnect seconds earlier than with full flaps, which gave the crew enough height to recover from the subsequent 8 degrees pitch reduction and high Vz (100 ft lost in 2.5 sec --> 2.400 fpm).

[WojtekSz]

@Mmmayday38
whatever you did at the time has worked out fine. With the hindsight i cannot find better way of doing this. I believe many should be grateful for your instinct reaction to the problem. Because i think that it was instinct flying more than anything else - even reading through the desription takes longer time than you had to make decisions.
The sim test as described by M.Mouse show clearly that to reach positive results they had to start corrective immediately at 700ft. It is nice to know what would happen ;)
Would the new breed of low hours pilots know how to react in such demanding situation? Would they have enough flying instincts developed?

@suitcaseman + S.F.L.Y
thanks for correcting on the ILS :)

[WojtekSz]

@ S.F.L.Y
i believe you are right that appropriate situation awareness has significant influence on security of the flying. I do not know if the pilots may/should have turned the AP earlier but i assume the rules were not broken as this would be clearly stated in the post accident report.

As a pure coincidence, the flap retraction probably caused the AP to disconnect seconds earlier than with full flaps, which gave the crew enough height to recover from the subsequent 8 degrees pitch reduction and high Vz (100 ft lost in 2.5 sec --> 2.400 fpm).
do you really believe that retraction of flaps was a coincidence? Commended 17 sec before impact while the AP disconnected some 7 sec before impact?

Are you trying to prove it was human error?

[S.F.L.Y]

do you really believe that retraction of flaps was a coincidence? Commended 17 sec before impact while the AP disconnected some 7 sec before impact?

Are you trying to prove it was human error?

@ WojtekSz

I don't know what is so unclear in my statement but I never said the flap retraction was a coincidence (how could it be?!). What I meant is that by coincidence (as it wasn't the crew's intention) this flap retraction accelerated the occurrence of the pitch down movement at AP disconnect. Should the aircraft had few more knots to loose before reaching its lowest speed this AP disconnect and pitch down movement would have happened later, closer to the ground, with no more room to reduce the high Vz. Few seconds before the impact the Vz was way too high as the aircraft initiated a lazy stall.

You are talking about the low hour pilots and flying instinct. Where is the flying instinct when you are VMC, approaching stall speed with no available thrust and that nobody stops the AP to increase the attitude? The most basic flying instinct would command to take over manually just like in a trim overrun. Luckily the aircraft did it by itself and disconnected the AP as it reached unsafe limits. Is it really the aircraft's job to disconnect the AP when speed gets so low?

[M.Mouse]

Should the aircraft had few more knots to loose(sic) before reaching its lowest speed this AP disconnect and pitch down movement would have happened later, closer to the ground, with no more room to reduce the high Vz.

The autopilot disconnect was caused by a control input. From the report found here: (http://redirectingat.com/?id=42X487496&url=http%3A%2F%2Fwww.aaib.gov.uk%2Fcms_resources.cfm%3Ffile% 3D%2FG-YMMM%2520Interim%2520Report.pdf)

At 240’ the aircraft commander selected flap 25 in an attempt to reduce drag. As the autopilot attempted to maintain the aircraft on the ILS glideslope the airspeed reduced and by 200’ had reached 108 kt. The stick shaker activated at approximately 170 ft, and shortly afterwards the First Officer made a nose down pitch control input which reduced the aircraft pitch attitude and caused the autopilot to disconnect.

[S.F.L.Y]

M.Mouse, you're right about this control input which is hardly reflected in the data report (no pitch decrease before AP disconnect). Anyway this happened 6.5 sec after speed dropped below 110 kts. At that point there was nothing else to do than lowering the nose to save speed (by increasing Vz). It's not only a matter of trading Vz to save speed to fly above Vs, extra speed is subsequently required to absorb some of the Vz prior to impact. Maintaining a speed just over 100 Kts couldn't reduce the Vz below 1400 fpm.

[WojtekSz]

@S.F.L.Y
what i read from your comments is the overall idea that if the PF would have done something (lowering the nose) earlier the plane could have landed as usual. Is
that right?
What i do see from the accident report is that PF has reacted (increased thrust) about 5 sec after the speed got below 135kt, and this would be about anyone would take to wait for the AT to correct the speed. At that time i would not expect ANY pilot to start lowering the nose - would you believe otherwise?

[S.F.L.Y]

What i do see from the accident report is that PF has reacted about 5 sec after the speed got below 135kt

We shouldn't have the same report since in mine the X axis is graduated in 2 sec increments. My reading shows that after the speed got below 130 kts you have 13 units before AP disconnect, meaning 26 seconds... How many Kts of deviation are tolerated on approach during a JAA IR test flight? The same graph shows 7 seconds below 110 Kts before AP disconnection. With no offense to the crew this seems to be a lot of time, especially when Vref was lost for over 20 secs.

[maynardGkeynes]

Question remains, would it be recorded the moment the spars moved from their open position or would a record be made only if the spars reached their closed position? In other words, if an uncommanded partial closing of the spars had occurred which rectified itself before they reached the fully closed position, would that have been recorded? If only recorded when reaching closed position: spars take up to 15 seconds to fully close so if an anomaly lasted anything less than 15 seconds and the spars moved back to their open position, they could have restricted fuel flow considerably without having a record of it and, as reported, the spars would be found in the open postion.The report uses the term "movement," which would seem to cover that:

A detailed examination of the spar valves and their control system revealed no pre‑existing defects and a thorough review of the control system indicated that uncommanded and unrecorded movement of the spar valves was not possible.

[WojtekSz]

we have the same report ;)
the difference is that you seem to believe that the first crew action was commanding nose down while i seem to follow the report thinking that 'the autothrottle and the flight crew commanded full thrust' and this has happened much earlier - just after the speed got below 135kt or latest
And to me it is fully understandable as adding more thrust is what most pilots do to add speed while landing :). And since B777 is a jet hence it took a while to acknowledge no speed increase. And all this is the time AP was constantly increasing pitch.
I would not consider take this time as no action.

[WojtekSz]

S.F.L.Y; I look forward to reading the report on how you handled your emergency when it happens one day. Must be incredible to be such a sky god with all the answers!
suitcaseman: i am fully with you on this :)

[S.F.L.Y]

Quote:
S.F.L.Y; I look forward to reading the report on how you handled your emergency when it happens one day. Must be incredible to be such a sky god with all the answers!
suitcaseman: i am fully with you on this http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/smile.gif

At least two guys are having fun. I don't care about criticizing the crew, I'm just interested in understanding how they reacted or not and why. I just observe a certain lack of action while speed decayed and I want to learn from it. If it happened to them it might well happen to me as it would probably happen to most of us. We very often act far from the most logical strategy and analyzing this is certainly a good step in improving flight safety, at least better than randomly distributing safety medals. Now if this also amuse people then it's even better.

Thanks god my personal experience of emergencies is limited to a single good ending event. Not because I'm a sky god but because I had good support from the ground.

[WojtekSz]

@S.F.L.Y
We very often act far from the most logical strategy and analyzing this is certainly a good step in improving flight safety

could you pls elaborate on what would be the most most logical strategy in this case? This might help the me (possibly also others) to understand your point.

[S.F.L.Y]

could you pls elaborate on what would be the most most logical strategy in this case? This might help the me (possibly also others) to understand your point.

Again, this is not the point. Some found out that different tests in the sims could lead to different results. Fact is that in real life crew's reactions are what they are, and not always appropriate since the human brain needs to update its situational awareness and subsequently its strategy. This is why we are trained to perform some reflex actions to some alarms. A normal reaction to speed deviation from Vref is thrust correction, which was attempted by the crew in this particular case. Of course it takes some time for the crew to realize the action is ineffective. At this point the speed keeps going down and the crew naturally focus on sorting out the thrust issue as its difficult to admit you are now flying a glider. This particular point is the most critical as this is when the have to accept the problem and look for a different strategy. It is very interesting to me to see that actions were taken on the flaps (drag reduction strategy) prior to taking manual pitch control. It's probably a much easier mental process to give up on the initial flap setting than on the AP ILS approach. Taking over manual control of a critically low speed and powerless aircraft is a natural decision for any pilot. Why did it happen so late? My point is not to criticize the pilots, but to understand why they didn't take the actions we could expect in such situations.

In other words I don't want to know if I would do better than them, I want to understand why I might be doing the same thing. Hope this time my point is clear.

[Joetom]

Apart from one post that mentions flap to 20 and using ground effect and flaps to 30 with loads of information to pre plan in a sim.

The above does/may not include what was going wrong with which systems and how much information was avail for the crew.

The aircraft may of had more problems than just all donks rollback.

The crew were near the end of some very long flights and all that goes with that.

It still appears to me they put that bird down in a good spot with the right speeds and angles to make a nice story.

Max respect to all the crew, you made a great team on that day, you will never buy a drink in my company, happy new year and all the best for 2010.

[suninmyeyes]

My comments were based on my experience of recreating it in a simulator several times and 2nd hand reports from the guys who were at the front.

The flight data recorder did not show the final up elevator movements as it stopped recording before impact.

In the recreation we attempted to deal with it as though we were not expecting it. We failed to make the runway on all attempts and ended up pretty much in the same position. There is only about 30 seconds from first recognising a problem to hitting the ground and the first 15 seconds or so is spent trying to evaluate the problem and there is a sense of disbelief that neither engine is responding. The EGTs are normal and uniform and there is no Eicas indication of engine failure.

The low speed protection you refer to is only valid with the autopilot engaged. With the autopilot disengaged there is an autothrottle wake up which would have been of no use as it simply advances the thrust levers which had already been advanced but the engines had not responded.

A flap 25 approach requires less thrust than a flap 30 approach and faced with a loss of thrust with flap 30 extended there is an instinct to raise the flap by one stage. In a normal goaround on the 777 even from 50 feet you still immediately retract the flap from 30-20 or from 25-20 even before you have obtained a positive climb because the sink is negligible and there is a reduction of drag.

In the recreation there is a high rate of descent before touchdown but it is fairly instinctive to initiate the flare early and commensurate with the ground rush rather than the radalt calls. To raise the nose and arrest the descent rate requires a much greater application of up elevator than normal. Approaching the stall the elevator feel makes the elevator artificially heavier but if you pull a bit harder you can still obtain full up elevator and incredibly effect a touchdown IAS of just under 100 knots. We ended up with full up elevator on all touchdowns and I understand this is what happened for real.

Just bear in mind that only one passenger was injured. I believe that was because they got the flare exactly right. Without that the result may have looked like the Turkish 737 at AMS. Well done chaps.

[S.F.L.Y]

I believe that was because they got the flare exactly right. Without that the result may have looked like the Turkish 737 at AMS. Well done chaps.

Two factors are involved in such kind of flares: the timing and the available energy. The less you have of the second, the less margin you have for the first. As you said the disbelief most probably contributed in delaying the moment where they ad to admit this would be a deadstick landing. Until the AP disconnection at a very low speed, they probably were probably keeping hope of making a normal ILS. When they finally got the proper situational awareness the speed was already way to low and nose had to be pushed down. Fortunately the plane had just enough height to recover the few knots to neutralize some of the Vz.

I think AMS was a different story, the aircraft made a much more ample flare (it had more energy to do that) leading in a much higher impact attitude at much lower speed. In that case casualties were not caused by the aircraft rate of descent but by its high nose up attitude which led to a violent front part momentum on impact.

[WojtekSz]

S.F.L.Y
It is very interesting to me to see that actions were taken on the flaps (drag reduction strategy) prior to taking manual pitch control. It's probably a much easier mental process to give up on the initial flap setting than on the AP ILS approach. Taking over manual control of a critically low speed and powerless aircraft is a natural decision for any pilot. Why did it happen so late? My point is not to criticize the pilots, but to understand why they didn't take the actions we could expect in such situations.
if you would finally accept that flaps 30 are just like huge airbrakes then getting away with such brakes is clearly the most important item when trying to stay in the air, especially that at some 400ft is a shade too early for a flare.

Until the AP disconnection at a very low speed, they probably were probably keeping hope of making a normal ILS. When they finally got the proper situational awareness the speed was already way to low and nose had to be pushed down. Fortunately the plane had just enough height to recover the few knots to neutralize some of the Vz.
You may be right that for some time the crew had waited to see the results from retracting the flaps. But i would not bet too much on the crew expecting to stay on the ILS path and make it to the runway securely as usual.
(1) AP has not turned itself - it was turned out by the control movement from the flight crew. (2) Nose was pushed down and at the same time they have used ailerons+possibly rudder to turn right (in order to miss the concrete runway surface to avoid fire)
They had made a perfect flare - you can see it from the main wheels crushed into the wings - but what is more important is that they had managed to keep the plane flying (arrested speed decay and made typical stall avoidance maneuver to gain the speed). With the vertical speed constantly increasing the higher the plane speed the better was the chance to glide to the ground instead of falling on it. And with higher speed the control movements had better chance of success.

[Green-dot]

@ maynardGkeynes,

The report uses the term "movement," which would seem to cover that:

Thanks, movement is indeed what the report uses for system description. This seems to cover the issue when movement is interpreted as "any" movement. Perhaps the fuel cut-off switches (switch position) and spars are also separately recorded parameters.

The report also mentions - quote: "Any uncommanded movement would have been recorded on the FDR and warnings would have been enunciated on the flight deck." - unquote. Regarding the warnings, they would indeed be enunciated, but only if there is a disagree between the spar control relay and spar valve position (stuck valve). Apparently no warnings if the valves, slaved to the control relays (not the cut-off switches), follow relay command if i'm correctly interpreting system operation . . . but i could be wrong.

Anyway, the report is quite definitive regarding movement being recorded so i will leave it to the experts involved with the investigation.


Regards,

Green-dot

[S.F.L.Y]

but what is more important is that they had managed to keep the plane flying (arrested speed decay and made typical stall avoidance maneuver to gain the speed). With the vertical speed constantly increasing the higher the plane speed the better was the chance to glide to the ground instead of falling on it. And with higher speed the control movements had better chance of success.This is exactly what I'm saying. Now you seems to be convinced that retracting flaps from 30 to 25 is a much higher priority than to stop the AP pulling on the nose...
On a constant path (ILS) a flap retraction requires an AOA increase, which is opposite to what is required to increase the speed (AOA reduction). Retracting flaps in order to reduce drag at constant AOA would require a steeper path and in order to increase the speed the AOA would need to be reduced. The speed didn't decayed because of the flaps but because the AP was constantly increasing the AOA. That's the first thing to stop in order to preserve energy. Flap retraction from 30 to 25 is only improving gliding efficiency once AOA and speed are under control.

[WojtekSz]

I would not bet a lot on maintaining the ILS path as the flying crew priority ;)

Anyhow, following sequence was used:
1. push the throttles fully up, wait for results
2. repeat push the throttles up, wait for results
3. reduce flaps, wait for results
4. push the nose down, steer to land
5. get the plane on the ground, evacuate all passengers
what would you propose to improve in this sequence? how would it influence the outcome?

[S.F.L.Y]

I would not bet a lot on maintaining the ILS path as the flying crew priority http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/wink2.gif

Anyhow, following sequence was used:
1. push the throttles fully up, wait for results
2. repeat push the throttles up, wait for results
3. reduce flaps, wait for results
4. push the nose down, steer to landObviously after the second unsuccessful attempt of thrust increase something else had to be done to save speed. Retracting flaps on the ILS is not increasing/saving speed, on the contrary, maintaining the ILS (which btw leads far beyond the threshold) is actually the only reason that caused the speed to decay.

When you fly a glider, speed is not constantly decreasing because of the lack of engine or because of a wrong flap setting. Speed only decreases if you increase the AOA, ie when trying to follow an unachievable flight path.

When the crew detects speed deviation it first acts on the thrust. If this is unsuccessful, there is only one way to save/increase speed: acting on the AOA/flight path. As such, without available thrust, AP disconnection and AOA control is the number one priority, acting on the flaps while the AP keeps increasing the AOA is totally irrelevant. While I understand such a wrong sequence can happen with short reactions delays, I'm really surprised that you can't get it after a couple of days of discussions behind a computer.

[korrol]

A very interesting discussion . If it's correct that the autopilot wasn't disconnected until 175 feet there would surely have been hardly any time to attempt anything much by way of manual flying.

[BoeingMEL]

I'll not throw mud or ridicule any particular poster in this forum.... but there are claims being made which would have a 1st year student of aerodynamics choking on his beer.

Please remember guys that this unique event came at the end of a long sector..and it was an event which was neither expected nor trained-for.

Double-engine roll-back late on approach with inadequate/confusing instrument readings. We've had 2 years now to consider this event - supported by special and update bulletins from the AAIB.

Those guys had less time to diagnose and react than takes most of us to punch a number into our cellphones. I could be in a minority here but my belief remains that the happy outcome more than justifies the fact that, despite their limited very options, they discharged their obligations in a thoroughly professional manner. :D Happy New Year to all bm.

[RatherBeFlying]

As many previous posts have summarised:

Until the rollback, the a/c was in a configuration of flaps, gear, thrust and AoA that maintained the g/s at the selected speed.

Thrust is reduced, a/p attempts to maintain g/s at expense of speed by increasing AoA while the crew is sorting out what is going on.

The drag from the flaps will accelerate the speed decay resulting from loss of thrust; so, reducing flaps will reduce the rate of speed decay at a cost of having to lower the nose to regain speed.

You then end up substantially lower, but in this case the resultant approach path fortunately happened to remain above the obstacle clearance slope until hostile structures and terrain were cleared.

In gliders a high drag approach is a steep approach. With certain flapped gliders, maximum flaps give you a very steep approach. A good way to get yourself in trouble with such a glider is to select more flaps early on final than will allow you to reach your desired touchdown point because decreasing flaps may require you to lose more height on final than you might have available:uhoh:

In contrast to jets, a glider with max landing flaps will approach substantially nose down until flaring just before hitting the ground -- same applies to a C-172 forced approach with 40 flaps. In both cases the airspeed decays very quickly when the nose comes up.

A jet with max landing flaps approaches nose up courtesy of thrust.

It would be interesting to hear of any simulator landings with max flaps and idle thrust from height.

[S.F.L.Y]

Suitecaseman, I'll not enter you sarcastic game. We are talking about low speed in a specific configuration. In their situation it was no more a matter of slowing down the speed decay but to immediately stop and reverse it. Reducing flaps on the ILS is not improving a low speed situation, on the contrary.

Do you seriously think the guys at Boeing designed the flap 30 only to induce more drag and burn more fuel on approach? Look at the report and see what happened when the flaps were retracted: the plane went slightly below GP causing even more nose up AP input. The low speed and reduced flap setting immediately triggered the stick-shaker.

If 105 kts is too low with flaps 30, how couldn't it still be too low with less flaps? With a flap 30 config at such speed there is no other way than acting on the AOA to reduce the margin with Vs. Retracting flaps while increasing nose up inputs will only get you closer to Vs and this is why the stick-shaker activated when the flaps reached 25. With 2 pilots in the cockpit you can't tell me that playing with the flaps was the only option they had. If you don't take manual control when you aircraft is about to stall with no thrust then please tell me, when do you think it's time to fly?

In a glider you don't use drag to control speed but slope. Speed is controlled by primary flight controls.

[WojtekSz]

S.F.L.Y
i have asked if you could propose some better actions to take - and what is your porposed action:
Obviously after the second unsuccessful attempt of thrust increase something else had to be done to save speed. Retracting flaps on the ILS is not increasing/saving speed, on the contrary, maintaining the ILS (which btw leads far beyond the threshold) is actually the only reason that caused the speed to decay.
...
When the crew detects speed deviation it first acts on the thrust. If this is unsuccessful, there is only one way to save/increase speed: acting on the AOA/flight path. As such, without available thrust, AP disconnection and AOA control is the number one priority, acting on the flaps while the AP keeps increasing the AOA is totally irrelevant. While I understand such a wrong sequence can happen with short reactions delays, I'm really surprised that you can't get it after a couple of days of discussions behind a computer.sorry but seems that you should rather concentrate on gliding than discussing flying jets or aerodynamics of the wings with flaps.

Looks that You are the only one that does not get it: so for the last time: flaps enabled LONGER stay in the air (aviate!) - if you look at the diagram from Report you would see that after nose-down command the speed has stayed relatively constant but the flight path (repeat - fligh path NOT the ILS path) decayed - the plane started to fly faster toward the ground. If you would draw the Radio Altimeter line appropriate for this speed (last 6 sec of flight) immediately from the point when the flaps were commanded you would see that the plane would have arrived on the ground some 4secs earlier - with much higher vertical speed and 200 meter earlier. Results would be devastating.

Not that the majority is always right but please make an effort of reading once again last 2 days worth of posts. Then discuss your point with anybody you know who flies big jets. And respond if you would still have anything new to add...

[misd-agin]

suitcaseman - "I suggest you ask your flying school / instructor for a refund. Speed is determined by a combination of pitch attitude (AoA), thrust and aircraft configuration."

So if speed is changed by a/c configuration, and going from Flaps 30 to 25 was a good thing, why weren't more flaps retracted?

[Mike X]

Flame me if you will.

So if speed is changed by a/c configuration, and going from Flaps 30 to 25 was a good thing, why weren't more flaps retracted? It's a trade-off. Too much flap retraction at that height and speed, you drop like a stone. Hope you're not a pilot - no offence intended.

My apologies, misd-agin, I see you are a pilot.

[CONF iture]

WojtekSz, for such a case of thrust deficit, deliberately accepting to let the glideslope drift over would definitely extend the gliding distance.
Not here to judge the BA38 crew as I would be more than happy to have done as well as they did, but purely aerodynamically speaking, SLFY is not wrong.

Mmmayday38, as we have the privilege to have you on board here, would you like to comment on those words (http://redirectingat.com/?id=42X487496&url=http%3A%2F%2Fnews.bbc.co.uk%2Fplayer%2Fnol%2Fnewsid_7190 000%2Fnewsid_7194700%2F7194714.stm%3Fbw%3Dbb%26mp%3Dwm%26asb %3D1%26news%3D1%26bbcws%3D1), or is it too early ?

[misd-agin]

suitcaseman - you're losing me. They were at Vref -17/18 kts. Yes, reducing flaps decreases drag. It also decreases lift. If they really wanted to decrease drag Flaps 20 (mid range slats) is a large drag reduction.

You mention engines, etc, etc. In this example they were a glider. Power was low and fixed.

I don't know, and I doubt you know since you havn't published the numbers, if reducing flaps to 25 from 30 was a net improvement in performance in this case. I tend to doubt it and think that maintaining airspeed was more important.

But we've had months to consider this and still don't know the answer. The crew had seconds.

[S.F.L.Y]

Guys, we all agree that at such a low speed the priority is to stop it from decaying and eventually recover some. Without thrust the only thing to do is to reduce drag. Retracting flaps is definitely reducing drag, but this is only effective when you don't create more drag somewhere else (ie by increasing the AoA...).

In terms of drag reduction retracting flaps might be a good thing, but totally irrelevant when you simultaneously let the AP add more drag by increasing the AoA trying to follow a wrong flight path.

To answer WojtekSz's question, the first thing to do when you realize you have no more available thrust is to recover and maintain the best gliding speed, which you won't achieve through flap retraction. In other words the PF should take manual control, control speed and eventually call the PNF for flap reduction.

WojtekSz, can you tell me why according to you the AP shouldn't have been disconnected before selecting flaps 25? Why maintaining the ILS all this time? To me the AP just spoiled all the benefits of the flap reduction which induced even more drag as the AP had to correct a slight deviation below GP induced by the flap reduction.

What was Sully's first action when he lost both engines? Take manual control or aircraft reconfiguration?

[M.Mouse]

Take manual control or aircraft reconfiguration? I don't know what Captain Sullenberger did but in the East Midlands B737 accident some years ago I seem to recall that the captain immediately taking manual control dramatically increased his workload and certainly did not help his attempts to deal with the problem with tragic consequences.

In my own company it is a broad rule that using the AP and handing control to the co-pilot is the preferred initial actions which then allows the (usually) more experienced captain to concentrate on managing the problem with as few distractions as possible.

Non-pilots will possibly not appreciate how much mental capacity manual flying involves especially with a non-normal condition.

[Rainboe]

555555555555555555555555 (http://pict.com/expo/3660311/5742adb005)

[go around flaps15]

Here here!:D

[TIMA9X]

By Rainboe: Why can't people just accept 'all's well that ends well'

Yep could not agree more, everyone walked away including a couple of (modest) hero pilots who did a damn good job in a matter of a few seconds!

[S.F.L.Y]

Very interesting remark about the AP and pilot workload. For sure the AP is here to assist us, provided we use it correctly. Good remark from Suitecaseman regarding using the AP to hold best glide speed. In this particular case the AP was not set to assist the crew in maintaining this best glide speed. The AP basically reduced and maintained the speed well below this best glide speed, thus shortening the gliding distance and causing high Vz impact. The AP which was supposed to assist the crew basically badly deteriorated the situation and shouldn't have been kept for so long on the ILS. The aircraft was trimmed for Vref, simply disconnecting the AP would keep it flying at a more appropriate speed and extend the gliding distance. Instead of that the aircraft was maintained on a wrong glide path at cost of precious speed. The AP not only lead to reduce the gliding distance, but also Vz control.

[Captain Airclues]

S.F.L.Y

You say that the actions that you propose would increase the glide distance. But what if you had done that, but not quite made it to the runway. The gear would have been damaged by the soft earth, possibly causing a fuel leak. However, because of your longer glide, the aircraft would be travelling much faster when it reached the concrete, with the possibility of sparks igniting the fuel.
The actions that the BA038 crew took resulted in everybody walking away. Can you be certain that your proposed actions would have achieved that?

Dave

[Cloud Bunny]

First off, Rainboe, couldn't agree more with the post.
Just to add something to this and I'm surprised none of my colleagues have got in on this (unless they have and I missed it) but we have had the benefit of some Boeing guys flying around with us for the last few months including some guys who test the 777s. We're also looking into this and other incidents in our SIM checks this 6 monthly period. What is being preached by Boeing to us is that in this scenario there are 2 main points:
1) Leave the flaps where they are.
2) Maintain VRef, even though this means you have to drop the nose and "accelerate" towards the ground. It gives you enough energy to flare the aeroplane enough to reduce the 'hit' on the ground.

Even applying this you aint gonna make the runway and as the guys from Seattle say you have to do the best with what you're left with. Which essentially sums up to me what the guys on board did that day and in doing so managed to get the aeroplane on the ground in a state so that everyone could get off, aided in no small part by the fact that Boeings are built like tanks!!

[40&80]

Good idea to run the whole approach through in the sim. and see if the aircraft would have done a better job doing an auto land with land flap and no pilot input at all.
If it would have crashed...the pilots did good...if it would have auto landed on the runway they did bad.
My money is firmly on the pilots and against the folk who think an aircraft does not need pilots and can be flown by an Indian call centre.

[WojtekSz]

the more i think of it the clear it is that:
(1) the crew made incredible job! chapeau bas! this situation must have been tried in all sims by whoever had a chance to try it - nobody so far has claimed successful landing. Two years after the accident! And the crew has done it in some 40 seconds :D
(2) from what i read and analyze the flying crew actions (a) at first tried to reach the airport and miss the obstacles on the way and only then (b) concentrated on just landing the plane. For me this explain why they first went for distance - aviate - and only later for speed to flair and land.

After reading comment from Cloud Bunny i did some very rough estimations and it appeared that (the numbers are for single wing of B777 with area of 215m2, excluding the fuselage drag):
3deg AoA the geometrical wing drag area would be equivalent to about 17m2 with Cd=0,05 => drag 0,85
8deg AoA the geometrical wing drag area would be equivalent to about 36m2 with Cd=0,07 => drag 2,54
12deg AoA the geometrical wing drag area would be equivalent to about 44m2 with Cd=0,08 => drag 3,44
14deg AoA the geometrical wing drag area would be equivalent to about 58m2 with Cd=0,09 => drag 5,22estimated difference in geometrical drag area for 30deg flaps (over 25deg ) would be some 5m2 with Cd=0,3 => drag 1,5.
The overall wing drag estimation would be:
- flaps 30 + AoA 8deg : 1,5 + 2,54 = 4,05
- flaps 25 + AoA 12deg : 0,0 + 3,44 = 3,44
Result: total drag was reduced but this gain was not significant (about 10-15%) and was quickly lost due to constantly growing AoA.

so

SFLY had a point - confirmed by experience from Boeing sims - reducing flaps had much smaller effect than i have expected.

(the calculations are very rough and are for comparison only http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/wink2.gif - do not build your next a/c with these numbers := )

[Mmmayday38]

You are all mostly talking about theories, but I was dealing with gut feelings and I now know what 'flying by the seat of your pants' means. I had limited time during the 35 seconds that we knew we had a problem and there were a couple of theories that I recalled. However, although theories have 'their place', gut instinct and the view out of the window on the day also had it's place. I am not going to discuss or discredit the various theories that are being bandied around as they all are relevant in various situations.

I am struggling as to what I can write here. The final report will be released soon and I think you will all be relieved when it is out, I know I certainly will be. All of the speculation and assumptions will be laid to rest as the facts will be presented.

I know that S.F.L.Y is wanting answers and explanations and at this stage I am sorry that I feel I am unable to clear up his questions.

I can tell you that on the day a lot of things happened within a short period of time. At 480 ft it became apparent to me that we had double engine failure (in all intense and purpose, that's what it was to us), I chose to leave my First Officer handling the aircraft to allow me to attempt to diagnose and fix the problem. As a pilot you are taught that 'flying' the aircraft is only about 5% of commanding the aircraft! I checked the systems for obvious reasons that would cause the severe power loss and could not find a solution. I followed the acronym PPP - Plane, Path, People.

After I had checked all I could for the 'Plane' I moved onto 'Path'. In my opinion there was no way anyone would survive if we continued on the Path we were on. At the speed of 115kts I clearly felt from my visuals that the aircraft was not holding the glideslope and we were dipping under it and that I wanted to G/A but I knew we couldn't. The visual location of the impact from my seat at this point, with a vert speed of approx 1800fpm and a gusty headwind was well before the perimeter road - more akin to WojtekSz' post 2743.

After 12 years on the 777, I know how she feels and she felt very draggy, I had to reduce drag. I couldn't raise the MLG as it was obvious we were going to crash and we would need it, plus the drag would have increased as the main doors are lowered first, before the decrease. At this stage I felt certain there would be 100% fatalities. At 240ft I selected flap 25 and I immediately noticed the difference, I felt that fatalities had reduced to 50% from making this action.

Boeing have been testing this in their sim and I have seen their findings, for this reason I am bewildered by Cloud Bunny's post 2757 and what is being taught in the sim.

[fotoguzzi]

(SLF, here). Thank you for your posts! (I had been hesitant to respond until I gathered from the professionals that you were definitely who your nickname and bio indicate.)

I just wanted to say that I appreciate any pilot who continues to make the most of the situation right now, no matter what caused the problem in the first place.

Even the late Captain McBroom in the fuel-exhausted United Flight 173 DC-8 here in PDX continued to fly long past the time when it would have seemed to make a difference. As a result, he and almost all the passengers walked away.

So, thank you and your crewmates for keeping at it until the eventual happy resolution.

[WojtekSz]

Mmmayday38: thanks for this insight!

[Wannabe Flyer]

Mmmayday38

First of from an SLF thank you!

Secondly as I browse various scenarios and analogies of what is being said in various posts I would as a non technical person (humble SLF in awe)... ask this question.

Given your real life unique experience from which all walked away and god forbid it were to play out exactly the same, some day again in the future is there anything you would do different (as learned from this experience) which would have resulted in the outcome being even better than it already was?
:D

[korrol]

We are very fortunate indeed to have Mmmayday38 contributing here - and it's very gutsy of him to actually spell out what happened and how he felt so frankly and in such detail. It's a real privilege to read his comments. Hats off to him.

We know that when the flap settings were changed by Mmmayday38 (at 240 feet) the autopilot was still engaged - so perhaps the move to Flaps 25 prompted the system to just tweak something somewhere to give the 777 just that tiny bit less drag to stretch the glide and gain those crucial extra yards.

Once the AP was disconnected though it was all down to human skill. ...But phew - it was right on the margin!

[S.F.L.Y]

Mmmayday38 thanks for your comments and I'm glad that you understand my point is not to blame anyone but to understand the mechanisms that lead the sequence of actions, wrong or not. We all are subjects to these mechanisms and understanding how and why we do things is very important.

I found this very interesting point in your comment:

I chose to leave my First Officer handling the aircraft to allow me to attempt to diagnose and fix the problem.

This is definitely how tasks should be split, my next question is why the manual aircraft handling happened so late (or what processed contributed to delay the AP disconnection).

WojtekSz's analysis is very interesting, but it is not totally correct to compare flaps 25 and 30 with constant AoA. However, the interesting point is to see how much of drag is added by deviating from the best glide AoA.

Provided that his numbers are correct, we see that between 3 and 14 degrees of AoA the drag difference is around 4.37. Maintaining the best glide AoA would not only save 3 times more of drag than the simple flap retraction, but also produce more lift (thus significantly increase the gliding distance and Vz control).

[Quality Time]

Having done a few double engine failure on final scenarios in the sim,I think the reality is you are doing well if you get out a Mayday call and Brace Brace to the cabin.

Don't stall the aeroplane and keep energy for a flare.

I'm surprised at the Boeing recommendation to keep leave the flap alone too although I know that's the case.

If you are flying at Vref +5 the speed drops below Vref before the failure is even recognised in most cases. (B737-800 F30)

Better lucky than good and so much the better if you are both!

[TIMA9X]

Mmmayday38,
Just to say thank you for your post, I don't want to enter into the what ifs; flap settings, AP etc etc etc full stop.

On the day that this happened which I remember so well (living on the flightpath for ten years) knowing what 480 ft is when the problem occurred, and it was a 777 my thoughts recall the same words until this day, Those guys in the cockpit did a great job!
Sir, next time I have to SLF I hope you are in the left seat!

To quote again a PILOTS PILOT
By Rainboe: Those pilots saved that planeload with their quick thinking actions.Yep they sure did!

[Mmmayday38]

Quality Time; I am interested to know what Boeing are now recommending pilots/airlines to do if this scenario happened again please? If, for instance, on finals, with gear down and F30, final approach speed at 1500 ft and a double rollback occurred, or similar double engine failure; what are they saying to do? This would be twice the height of the BA38 incident. Are they saying the same for all wind conditions/runway clearways?

Wannabe Flyer; In answer to your question... We had the best outcome on the day, and I wouldn't change the decisions. I would, however, have appreciated more time; both to deal with communications, options and the fact that more time would have meant more height! I have seen the figures, and wouldn't want to end up anywhere other than the BA38s' impact point... no further forward, no further back! I'm not saying we briefed to put it down where we did, but, at the time it appeared to be the closest 'safe and unobstructed area' to aim for. With hindsight, my impact point appears to be the location that would result in the least number of fatalities.

[bearfoil]

Excellent idea. It would save fuel as well. Had 038's GS been even slightly higher, with a 'below' figured in, no need for thrust to make the field. It seems to me a low GS is a margin that doesn't allow for minor drift below it. It is a hard deck. It also led the AP to seek a higher AoA. A long 3 degree is asking for fuel/waste.

[misd-agin]

Exactly the point, at some point allowing the aircraft to slow to 108 kts probably resulted in worse performance than maintaining Vref Flaps 30.

Quoting Boeing's recommendations probably has to be clarified or expanded. I doubt they recommend maintaining Flaps 30 if you're at 2000' AGL. At some point there's a tradeoff. Again, that's experience, experimenting in the sim, and a smattering of luck if you'd ever have to make that decision quickly.

Everyone's familiar with the drag increase at greater than Flaps 20. Getting to mid slats is key.

You can verify stall information for your a/c's stall speeds. First notch of leading edge slats typically is 50-60% of the total stall speed reduction. Additional flaps have a lot of drag vs. amount of stall speed reduction.

[RatherBeFlying]

As you increase flaps from zero, the L/D ratio decreases; i.e. you fly a steeper approach or you need more power to maintain the glideslope.

When there's no more power available and you're coming up short, you need to increase L/D.

Decreasing flaps does that, but you are also increasing stall speed; so, in a low energy situation with very few seconds to weigh alternatives, not decreasing flaps further once a survivable impact point has been achieved sure looks like the best way to minimise the risk of something else going wrong.

Mmmayday38 had to negotiate a tight squeeze between landing too short and increasing the stall speed too much; he looked out the window and did exactly what was needed:ok:

[Dont Hang Up]

These type of incidents are self evidently extremely rare. Therefore any change in aircraft or airfield operations to mitigate the risk must have pretty much zero downside in terms of safety.

[Mmmayday38]

There has been a recent fresh rumour regarding new procedures issued from Boeing, I find that to quench a rumour in its' early days is vital to preventing it spreading and gathering momentum.

I was bewildered as to what was being said so checked it with a 777 trainer friend that I know to question its' authenticity. He flatly informs me that Boeing definitely DO NOT recommend maintaining F30 in this incident on the777..

'Cloud Bunny', I am sorry that I felt I had to question your post #2757'; but I know from what I've read and seen from Boeing that this shouldn't be the case on the 777. Of course I have no knowledge as to what would or would not be right on other aircraft (so I will not make the assumption that what is right on 777 is right on an alternative Boeing) as I only asked 777 trainers.

[S.F.L.Y]

That's an interesting point but it's just a part of a whole situation. Boeing might recommend to retract flaps from 30 to 25 but I'm quite sure IAS control and initiating a best-glide speed recovery will be the priority once the lack of thrust is being confirmed.

To understand this simply imagine that you're already configured flaps 25 when the failure occurs: speed control is obviously the most important task to perform.

Once again I'd be very interested to know what prevented the PF to revert to best glide speed earlier, at least once flaps 25 were selected. The fact that manual speed control was only initiated when the stick-shaker got activated looks like a passive and not an active decision. Why? Retracting flaps was one thing but speed monitoring and control should have remained the priority. What interfered?

[punkalouver]

Anybody have a picture from the cabin of the 777 flaps in landing configuration. While riding as a pax, I was amazed at how near vertical the inboard flaps appeared to be on final. Looks like huge amounts of drag to me. Wonder if a flap 15 position would have helped even more(if it exists). Hopefully will be examined in the report. Woder what the difference in ref speeds is between the various larger flap settings?

[WojtekSz]

SFLY
Once again I'd be very interested to know what prevented the PF to revert to best glide speed earlier, at least once flaps 25 were selected. The fact that manual speed control was only initiated when the stick-shaker got activated looks like a passive and not an active decision. Why? Retracting flaps was one thing but speed monitoring and control should have remained the priority. What interfered?
i do not like to repeat myself but pls see my post #2743 (http://www.pprune.org/5423630-post2743.html) and mmm's explanation:
the reason to act manual ONLY AFTER the stick shaker was activated was to fly level as long as was safely possible to get closer to the airport area. Flying low angle approach and faced with double engine failure one have two options:

fly quicker and land shorter - possibly long way before the runway and in this case higher speed would mean more fatalities
try to fly as level as possible untill the last moment (stall alarm) and only then go for speed just enough to flare before touch downwhich method would get you closer to the airport flat grounds?
would you rather hard-land inside or outside of the airport perimeter? in case of fire what would be the time to get help from airport firemen in both these cases?

seems to be a no brainer to me - but what do i know ;)

[M.Mouse]

...the reason to act manual ONLY AFTER the stick shaker was activated was to fly level as long as was safely possible to get closer to the airport area.

You surmise.

They did not have the luxury of unhurried, logical analysis. They may or may not have been able to do things differently with better results but, given my guess they were overwhelmed by an impossible situation, the instinctive flap retraction was a gut feeling and saved the day, the late AP disconnect was a reaction not a planned action.

Why can't this pointless speculation cease and people just wait for the definitive account and analysis which will be published sooner rather than later?

[CONF iture]

WojtekSz,
the conception you have on what's going on in flight is biased, try to fly as level as possible won't bring you anywhere, but keeping the speed is your best bet to reach somewhere, especially in case of headwind.

[WojtekSz]

CONF iture,

maybe i have been unclear of what i see as flying as level as possible ;) - my fault since flying level flight was simply not possible without power!

i used the term 'flying level' as a short version of saying: to stay as close to level flight as possible with the existing plane configuration and airspeed, in order to achieve best horizontal progress with lowest loss of flight height.

It would mean most efficient use of whatever energy was available to get closest to the airport without stalling or loosing too much height.
The AP is surely not designed for such flying ;) but looking at the data from Interim Report it was pretty close to optimum.

We are talking about possible optimization for the dirty configuration plane flying close-to-stall at some 300ft. Hardly possible to solve analytically. Not so easy to replicate in sim. The crew has successfully solved it empirically. What we are doing is analyzing what they did in order to identify possibilities for any realistic improvement.

[cats_five]

<snip>
i used the term 'flying level' as a short version of saying: to stay as close to level flight as possible with the existing plane configuration and airspeed, in order to achieve best horizontal progress with lowest loss of flight height.
<snip>

The two are incompatible - losing height as slowly as possible and making best forwards progress. What you need is the second one - getting the best forwards progress. You fly at best L/D for that, and what that is will depend on the configuration of the plane and it's wing loading. However, it is faster than min/sink - losing height as slowly as possible.

Since the 777 has many different configurations, each one will have it's own best l/d and speed to fly, STF that will always be faster than the min/sink for that configuration.

I did find a nice animation on the Internet once which illustrating the differences between flying too slowly, at the right speed and too fast, but can't find it now.

There are a couple of Wikipedia articles which explain the theory:

http://en.wikipedia.org/wiki/Polar_curve_(aviation)
http://en.wikipedia.org/wiki/Lift-to-drag_ratio

However, my own view is that whatever the theory, MMM managed the situation well enough that everyone survivied and nearly everyone was (physically) unhurt. Will be very interested to see the final outcomes of the work going on at Boeing about handling this thankfully very rare occurence.

[S.F.L.Y]

Come on WojtekSz, achieving the best gliding distance is done by flying at best glide speed in the cleanest configuration (no flaps or ld gear) and certainly not by pulling on the nose till the minimum speed. When you have headwind you even need to increase speed over best glide speed. I don't know the best glide speed of the 777 in flaps 25, but it's usually very close to Vref.on many aircraft. The more you deviate from that speed, the more you shorten your gliding distance.

There are certainly many explanations for the late AP disconnection, but you can't seriously pretend it was intentional in order to extend the gliding distance as it's clearly achieving the opposite. Retracting flaps was not all as some people seems to believe, speed control is much more important in such situations.

[BoeingMEL]

..I developed senses and reactions which enabled me to pre-empt changing conditions on the 733, very much in the way you describe.

I know from mutual friends that Pete was a loyal BA employee, a pleasure to fly with and a true professional. Job done! :ok: