Phil Gollin

You ask how so similar a thing can occur in two separate places but with a time difference between them.

I have to say that I can't see that there is much difference in reality, six or seven seconds can be accounted for by a slightly different amount of ice (in some form) being present and the 'detaching' behaviour of that accumulated ice by the slightly different fuel flows noted in each engine.

Since this is the only case ever seen of this nature, there are no statistics with which to determine whether the similarity seen is a coincidence or not.

Let's face it, it has been shown that ice is the only remaining possibility, and how else can such a restriction occur other than that some form of solidified ice arrives at a constricted area in high concentration, overwhelming the ability of the fluid part of the flow to pass at sufficient rate.

The presence of a quantity of water in the tanks has been determined. Whilst it would appear to have been small is there any possibility that the location of the water (or ice at that stage) could have become focused/concentrated in one or two particular areas and then gone through to the engines as a slug?

I appreciate that the volume of water present does not appear to have been sufficient to cause the problems experienced.

Could it have been underestimated? Could it have been in the wrong place at the wrong time?

Jim

Actually according to some "not-easy-to-dismiss" sources, had the autopilot been disconnected immediately, and the A/C flown in "longest glide" mode, it would have (barely) made to the runway, and landed almost normally.

If you're curious, read the thread with a title like "BA038 pilots given a medal" or something like that.

Another thing that can surprise you, is that there is no training for "dead stick" landings (dual engine failure), in any airline of the world.

All in all, the positive outcome of this incident is due to sheer luck. Sorry if this lessens your trust in the safeness of flying.

Jim,
Almost certainly in the wrong place at the wrong time...and yes, the drift seems to be with such a small quantity of water, that it perhaps layered or was picked up all at once due to the change in attitude during the latter stages of approach.

It's interesting to note that one of the recommended changes in operational procedures may be to vary throttle settings more before or during descent (the implication being I think, so to stir up or purge wtaer/ice near the scavenge pumps)

A question I put on one of the early pages of this thread was along the lines ofThe answers to that were along the lines of... 'Yes, quite possible, and there has even been a move towards that situation due to approach profile that specifically encourage it' (fuel usage and noise abatement I believe)

[please clarify or correct if you feel this is wildly inaccurate, I haven't re-scanned those responses as yet]

And they may well have taken a couple of roofs and the aiport fence with them too - not to mention the need to take action within seconds when the nature of the problem is unclear.

Apart from the "not-easy-to-dismiss" sources bit !
I'd say that statement is very easy to make in retrospect, from one's armchair, very, very easy and even then maybe not so accurate, unless immediate means immediately the engines didn't pick up i.e. how does one know they aren't about to pick-up when they have for every flight one has ever flown before, how long does one wait for an uncertain event... there is little if any training for 'engines not picking up after throttle re-adjustment 720' agl runway ahead' , surely?

Yes, there was luck, and there was also some correct and non-panicky actions taken on the fight deck that ensured BA038 just got over the peri-fence and flared heavily enough with what remaining airspeed it had such that vertical speed at touch-down was low enough to prevent a complete break-up - as we know from Madrid, almost always resulting in fire and fatalaties.

However, I would like to add that I think parading the pilots in front of the press the next day was in extreemly poor taste and judgement... whoever planned that should be fired, they both looked horrified at having to endure that!

el #
 

Maybe not, but there have been instances before where all power has been lost and crew have "controlled" the AC. i.e. a BA 747 SIN to PER when it encountered volcanic ash over Indonesia and lost all 4 engines. They did manage to re-start them before their collision with the planet.
I think that all PF would have innate ability to naturally react to flight needs - as in this case where it was reported that PF lowered the nose to stop the stick-shaker.

Flynerd

I did not want to stir debate again on the matter of how the lading should have been flow, not having even a tiny bit of the necessary competence on the matter. I also recognize that anything said now is purely retrospective.

I just wanted to inform nhs that there are different opinions on the matter, so he/she can look in the relevant thread and form an informed opinion from there.

However rib4t4, on the subject of "need to take action within seconds", well that is exactly what the crew didn't do, at least regarding the autopolit/autolanding, that was left engaged for the last critical seconds of the landing.

Again, I don't know if the a/c would have taken roofs or fallen from the sky if flown manually. What I know is that some real pilot did a real sim test and it seems like a normal landing could have been completed. Do wath you want with this notion, and if you think that in these dramatic seconds the Cap.n came the conclusion that A/P would have landed acceptably despite virtually no thrust, and consciously left it engaged instead of taking control, that's OK with me.

Finally be assured that I do not have any agenda or position to defend, and be assured this is my 2nd and last post in this thread.

Can´t be too expensive, since everything in NATO from tent stoves, jeeps and tanks to fighter aircraft run on the stuff. (F-34 / JP-8)

And civ a/c too come to think of it.....

Power Was Added In The Holding Pattern
 

The AAIB report says power was increased upon entering holding. It even specifies the fuel flow rates at that time.

Hatton Cross. Details of a close call with surroundings.
 

For those not familiar with LHR ( Hatton Cross tube station area). A little local geography expanding on the the BBC map of the area.
The BBC showed a car hire depot but not the filling station next door.
Sadly a BP petrol (gas) station seems more newsworthy.
The busy A30 4 lane major road is only a fence from the perimeter road.
The Green Man pub ( the noisiest pub in the world near a civil airport ?) is also one of the roofs that had a near miss.

A view from Hatton Cross underground station across the A30
with a normal approach of a SQ 747 shows how close the 777 was from an even worse event.

http://farm1.static.flickr.com/50/13...1ff0d30d0.jpg?

http://farm1.static.flickr.com/50/13...g?v=1158408144



A view from the other side of the station
The peri track is past the green traffic lights.
Just and only just to the right of the traffic lights is the landing location.

http://www.oxford-chiltern-bus-page....A340-buses.jpg
http://www.oxford-chiltern-bus-page....A340-buses.jpg

I disagree. A certain 737 operator did train for that event. If I remember correctly the number was outbound over the marker at 5000 above FE, complete normal PT and return for landing. It worked in the SIM!

Feathers ;

I have to say that I can't see that there is much difference in reality, six or seven seconds can be accounted for by a slightly different amount of ice (in some form) being present and the 'detaching' behaviour of that accumulated ice by the slightly different fuel flows noted in each engine. .........

......... Let's face it, it has been shown that ice is the only remaining possibility, and how else can such a restriction occur other than that some form of solidified ice arrives at a constricted area in high concentration, overwhelming the ability of the fluid part of the flow to pass at sufficient rate.


But this is like having your cake and eating it.

The engines had their commands at the same time, but the roll-backs occured at slightly different times, HOWEVER the effect on final thrust was almost exactly the same.

You say "ice is the only remaining possibility" - but this is what annoys me. They can only reproduce one aspect (the cavitation damage) but without any real expalantion (the two icing scenarios are not really supported by the report) so grasp that one straw. If they could reproduce the icing that leads to the cavitation damage AND show that that icing condition can be variable in time but not effect - THEN they would have something that would convince me.

Don't get me too wrong, as a cautious warning (as opposed to a "finding") I would be happy, but fail to see why this mysterious icing wouldn't affect 777s powered by other types of engines.

.

TREE

my airline also did some dual/all engine flameout landings in the sim.

I think that we could all benefit by this training.

Deadstick training?
 

Dual Engine failure "dead stick " not taught anywhere in the world?

Not so.

Dual Engine failure has been trained on each conversion I've had since about 1999, (two different airlines).

el #

Not correct. A large British Airline based at LHR includes total engine failure landing training in at least one of its current two engined fleet types.

What are you basing your statement on??

How long would it take to recognise this was an engine problem rather than an autopilot/ILS problem? Did I hear an early TV report that GA was called or am I mistaken?. They were still running and they had been cycling to maintain GS - it may not have looked like an engine failure for some moments?

Excellent report...

but I don't understand the apparent lack of logic between the prudent requirement for..."interim measures for the Boeing 777, powered by Rolls Royce Trent 800 engines" but only a recommendation that the authorities consider the implication to other engined 777's and aircraft in general.

Maybe they didn't want to get into commercial politics and passed the buck.

Since the specific mechanism is not understood I would have expected whatever interim action is taken on Trent engines to also apply to GE.

How much more efficient are the Trents?
To what extent does this reduce fuel flow in terms of cross sectional pipework terms? Significant?
The two Trent engines were exhibiting different (measured at least) fuel rates anyway!

My interpretation of the report is that the blockage was due to ice in the fuel delivery system prior to the engine unique part of the installation.

My conclusion would have been to consider both engines types equally subject to whatever caused the restriction at least until the exact mechanism is understood.

Comments?

<Phil Gollin>
Feathers ;

I have to say that I can't see that there is much difference in reality, six or seven seconds can be accounted for by a slightly different amount of ice (in some form) being present and the 'detaching' behaviour of that accumulated ice by the slightly different fuel flows noted in each engine. .........

......... Let's face it, it has been shown that ice is the only remaining possibility, and how else can such a restriction occur other than that some form of solidified ice arrives at a constricted area in high concentration, overwhelming the ability of the fluid part of the flow to pass at sufficient rate.


But this is like having your cake and eating it.

The engines had their commands at the same time, but the roll-backs occured at slightly different times, HOWEVER the effect on final thrust was almost exactly the same.
</Phil Gollin>

I like cake!

On the assumption that a similar ice/fuel mixture was present, then the fuel flow that could pass the obstruction would be limited by the consistency of the ice and the throat area it is trying to pass. This will be the same in both engines (although perhaps there is a 'handedness' to the fuel piping, I do not know).

<Phil Gollin>
You say "ice is the only remaining possibility" - but this is what annoys me. They can only reproduce one aspect (the cavitation damage) but without any real expalantion (the two icing scenarios are not really supported by the report) so grasp that one straw. If they could reproduce the icing that leads to the cavitation damage AND show that that icing condition can be variable in time but not effect - THEN they would have something that would convince me.

Don't get me too wrong, as a cautious warning (as opposed to a "finding") I would be happy, but fail to see why this mysterious icing wouldn't affect 777s powered by other types of engines.
</Phil Gollin>

Well, the latter statement is quite correct, and you will see that AAIB are saying that an urgent investigation into precisely that condition is needed, it clearly isn't just a Trent issue it's just that the one instance so far happened to be on a Trent-powered airframe.

As for the reproducibility, yes, so far they have shown that a problem is seen in circumstances not that alike to the real fuel system. More work is to be carried out to improve the test to mimic reality better. They may not succeed, but they have to try.

The ultimate mimic though would be a 12 hour flight from China in similar TAT conditions and flight profile with the same approach clearances, descent rates, power profiles. If they are lucky they get to see it happen again, but maybe this time with a 777 embedded in Hatton Cross tube station.

The other thing to note, they state quite clearly that very little is known about the precise effects of ice in fuel under varying circumstances. So a major research task would be called for to understand it better, that will take time.

Do you feel that it wasn't ice? Because there surely are precious few other culprits lurking.

Apparantly you airline types have been using the wrong technique for landing. In todays Daily Telegraph their esteemed Jorno David Millward - Transport Editor suggests that you use "Reverse Thrust"to slow the aircraft for landing. And there was me thinking it was a balance of thrust vs drag from flaps !!!. It any of you chaps would like to try this new technique, I will keep an eye on Sky News to see the results. I know that the Concorde could do this, on the inboard Olympus engines, but dont try this at home chaps