Not in a life time !! The aircraft just bled its energy so fast. Getting to the end of the runway was really fantastic.
You have to try to imagine the magnitude of such an event. As someone put very accuratly on the site earlier, no one knows what he would do in such a case. Trying to get the grip of what's happening and to think of a way to remedy ot it in a such a short period of time is hard to imagine.
I'm glad I had a chance to try it on the sim, it does give you an idea of what the unthinkable is about.

and it ends with:

..........

I understand, Me Myself that the elapsed time from loss of power to impact was 50 seconds +/-. Could you verify that from your SIM session?

The "update" is a final report on a June '06 Nott. East Midlands Boeing 737-300 accident/incident - but to be fair the AAIB website has a screwy revolving link, so if you click at the wrong instant, you something different than you intended. And it does say "5/2008 Update" - just updating on the wrong subject....

Likely what happened to Sky9

Afraid not and if it was, even in the sim, it did feel very very short. Bear in mind this is just something we did at the end of recurent training because we had 10 minutes to spare. No rocket science. We just wanted to get the feel of what these guys must have experienced. We started at 4 dme, configured full flaps and retarded the engine one after the other to end up almost precisely at the same spot. Didn't change flaps setting because we didn't think of it too busy flying, but then, no fence in the sim.
Again, caught in the real thing I really don't know what my reaction would have been and I just hope they would have been along Cpt Burkill's lines.
Any sensible pilot will think the same way.

All of us flying the 777 would really like Boeing to come up with some explanations so it can be fixed and allow us to relax a bit.

I have asked it again and again , what is the envoirnment envelope re temps for a 777? In the 320 it is SAT -70.

I note when they checked the fuel freeze temps at the accident site, they were -57c.

They had loads of juice coming into land (10 tons), fuel must have been like jelly for some reason....hmmmm.

Me Myself - I can well understand how you guys feel.

A question from someone whose regular steed is a C150. The report states that the autopilot disengaged at 175 agl when the speed had decayed to 108 knots. Is it normal to keep the autopilot engaged so late in the approach? Or were they exercising a Cat 3 autoland where (I guess) the autopilot stays engaged.

The report seems to pretty well squash any thoughts of fuel contamination, freezing etc. Also, it seems to indicate that there was nothing wrong with the fuel delivery system apart from the mention of cavitation damage.

What's left? Way back in this thread I (tongue in cheek) said 'Windows fatal error'. Is this what its going to turn out to be - the old 'blue screen of death'? Dilbert on a bad day?

Bearcat
OAT +8 or +10.Like jelly or like froth? or both?

The freeze point of the fuel may well have been -57C when tested, but if a kerosene is cooled to wax precipitation, wax drops out and is not redissolved into the fuel, then the freeze point of the Kero will be lower after the event. In other words the freeze point of the fuel would have been above -57C prior to wax precipitation, if it had occured.

However, if that were the case with BA038, the question arises what happened to the wax and why were no traces found? (I presume the investigation has included GC analysis of the bulk fuel and residual fuel on the filters for comparitive paraffin component profiling)

Xeque: BA fly a monitored approach. It was the FOs sector, so the Captain flew the approach for him. The FO took control at 750'. Now normally what would happen, the FO (in this instance) would have disconnected the autopilot, and continued to do a manual landing. What follows is conjecture, but it is a fair bet to say that, as the AT failed to respond, and the situation unfolded. Both pilots would have looked inside and gone "WTF". Best decision was, I would hazard to leave the autopilot in and try and work out what the hell was going on. During this small window a decision was made to retract the flap one stage. That saved the day. As the speed decayed the A/P disconnected, and they hit the ground.

Would hand flying a "fly by wire" aeroplane helped in these circumstances? No idea. Those who have tried it in the sim would suggest that they made the best of what they were presented with.

It is important to remember that they first had to notice the problem. Then they had to diagnose it, then they had decide what to do. All close to the ground in circumstances they would never have seen before, and never have been trained for. That they made the crucial decision to retract the flap that saved the day cannot be under emphasised.

What I do know is that, God forbid, If I am ever presented with something so unusual in such a parlous position, I can find it within me to do as well as those guys did.

/respect

BA38s engines "Hesitated"
 

Dear fellow PPRuNers,

Since the BA38 crew, unknowingly, flew a: "Green Approach" (idle) with the engine anti-ice system in "Auto" they probably had some core engine icing, that caused the hesitation.

That must scare, all involved in a B777 flight (app. 1000 times a day) with an average of 200 seats sold, equals 200.000 human beings and some in the leadership of BA, RR, AAIB and Boeing, sh..less.

That why, the AAIB did't find any signs of ice damage, it just melted away.


Oluf Husted

Nice bit of shameless self promotion there Oluf......:mad:

Thank you, also, for pointing out what "Engine anti-ice" is, as many of the airline professionals and the AAIB would OBVIOUSLY not have a clue as to what causes it or how to look for traces of it after an accident! :rolleyes:

Just because you can't find any ice in the engine doesn't mean you can't establish an icing condition using collected data!

"that caused the hesitation" - there was no hestitation, the engine was completely unresponsive and continued running at idle until impact.

PAXboy wants to know if the time from 4DME to touchdown equates to 50 secs, or there abouts. No one seems to want to tell him!

Assuming 180 kts average over 4nm= 80 secs.

Adjust the average, adjust the time...simple! :ok:

dear Oluf,

I read your anti-ice plea 'for your grandmother to understand' and found it not only very amusing but very interesting indeed. (I am a frequent SLF, and being an interpreter, was able to read your text in danish)
However, your analysis refers only to stator/rotor blade ice formation while taxiing and the way to get rid of it prior to TO and after landing. So if I understand you correctly, what you call 'the hesitation' of BA 038' engines could have been caused by ice debris, but can what happened to this flight (engines throttling down to somewhere above flight idle and staying there) be described as mere 'hesitation'? or do you think there wasn t enough time for the engines to resume normal operation? and how would this relate to the cavitation found in the HP pumps?

and, following from your theory, no 'green approach for you in certain weather conditions?

Fly safely.

Surely you're joking right ?? Unknowingly ??? This approach has been going on since basically .........the ice age !! I find myself repeating " Roger, 160 kt til 4 DME " in my sleep.
Since you are coming from 210 kt down to 180 kt and requested to keep 160 kt til 4, this is basically a green approach.
I suggest that, like the rest of us, you wait for the final report instead you make any phony assumptions.

PS Oluf, how often do you fly 160kts IAS fully conifgured at idle thrust?

:ugh:

BA38s engines "Hesitated"
 

Dear davecr,

According to the AAIB report, page 2, from feb. 2008 (latest): "The Engines initially responded but, at a hight of about 72o ft, the thrust of the right engine reduced. Some seven seconds later, the trust reduced on the left engine to the same level"

That is "Hesitation" in my book.

The different Jet Engine Producers, Airbus & Boeing and The Airlines has over the last 50 years been "Out of Synch" about recommendations and actual Anti-ice and De-ice Procedures.

And not until 1994, it was never admitted that, at idle power, the anti-ice systems does not work.

Oluf Husted

BA38s engines "Hesitated"
 

Dear davecr,

Anytime I had speed to "bleed of" but at 1ooo ft, (or at the very latest) 500 ft, pilots have to be "stabilized" and so it seems to be with the BA38 crew.

Oluf

Dear Oluf,

As I too aim to be stable at 500' on a daily basis, I am well aware of this :)

It seems to be a language problem here, as you seemed to suggest that the aircraft was idle all the way down to being at its "stable" criteria. Furthermore, our interpretation of the word "hesitation" seems to differ slightly.....

Nevertheless, I think you are out of order to be speculating about the cause of this accident, especially using the words that you did. Excuse me for having more trust in the AAIB then an engine icing enthusiast.

Can I also point out that this type of approach is not carried out unknowingly, but is highly encouraged due to fuel savings and noise restrictions in this part of the World? As mentioned before, min 160kts until 4DME or somewhere along those lines is the standard at London airports.

Dave

BA38s engines "Hesitated"
 

Dear borghha,

Right, no (fully computerized) "Green Approach" to me, but a late descent and a less than idle power setting when the anti-ice systems "on" is OK!

It is also valid, when airborne, what i wrote about run-ups during taxi "out" and "in. You need MORE than idle power, to get hot air enough, to keep the metal/platinium in the front end of a jet engine above freezing point.

So, my guess is, that the BA38 flew at idle power from FL400 to 720 ft, and even if the selected anti-ice "On" it does not work at idle, even if it should according to certifications.

Oluf

BA38s engines "Hesitated"
 

Dear Me Myself,

"Unknowingly" means, that crews very seldom stay at idle power during the whole descent, since ATC req. some "level flight" or "holding".

But the BA38 crew had a very light plane and "not headwind" during descent,
they even entered and departed "Lamborne Holding" descending at idle power.

Dear fellow pilots, have you read any other (and better) possible cause of this 104 day old mystery?

Oluf

Oluf

On a modern jet engine, which parts are actually anti/de-iced by "hot air"? The answer, I suggest, may help to focus some of the wilder speculation going on here.

And do you really think the absence of any "remaining" ice due to melting will have escaped the AAIB?

Oluf,

Is that your assumption or is it based on facts? The AAIB only mentioned that the aircraft entered the hold at Lamborne at FL110; it remained in the hold for approximately 5 minutes, during which it descended to FL90.

Although that would give an average 400 ft/min rate of descent, the aircraft may have maintained FL110 for 3 or 4 minutes before descending to FL90? No mention in the report how the hold was performed. Or does a descent in the hold include a standard descent procedure?


Regards,
Green-dot

BA38s engines "Hesitated"
 

Dear Starbear,

The jet engine "Lips", the compressors big-fan blades and the very first part
of the "core-engine" is kept above the freezing point by hot bleed air, if you remember to turn the system "on" and increase the power setting.

"The higher the temperature, the more severe is the icing situation" up to +10 degrees C. (since the cloud water content, at 100% humidity, is approx. the double at +10 C, than it is at 0 degrees C.)

The amount of ice needed to make the engines to hesitate, can easily be gone, before the AAIB gets around, when the ground temperature is/was 11 degrees C.

Oluf

Why only this one?
 

One thing is clear - the BA38 incident was self evidently an exeptional event. I am doubtful about how the engine icing theory fits this bill. If such a relatively unexeptional approach profile can cause this problem, why are B777s not dropping like flies?

BA38s engines "Hesitated"
 

Dear Green-dot,

I is my assumption, since also i only have the AAIB feb. report, but if BA38
just had some speed above "Holding Speed" when entering Lamborne at FL110 and was cleared to FL90 early, they could have stayed at idle power.

The AAIB report don't even mention if the engine anti-ice system was used,
very strange, since the actual weather was "Broken Clouds" over London.

Oluf

BA38s engines "Hesitated"
 

Dear Dont Hang Up,

During my 30 years of descents, I almost never did one without some level-offs or "Holdings", but I think, that was what the BA38 crew did.

And further more, I was almost always "Stabilized" no later than 1000 ft. and had my engine anti-ice system "on" when flying in and out of clouds.

Oluf

Oluf

Wild,wild speculation my friend. And for the record is the anti-ice system on the 777 not automatic..i.e.doesn't require "switching on" in the traditional sense.
Also i understand that at idle thrust adequate engine anti-ice is provided by the switch from low-stage to high stage bleed air. Otherwise no anti-ice would be available from high flight levels for long periods of time.
Just leave it to the AAIB who i'm sure will have considered this at some point QED.

BA38s engines "Hesitated"
 

Dear 3Greens,

Any descriptive of the Anti-ice systems (on most jet engines) claims to work, also at idle power, but that is mostly to comply with the certification, not in the real world.

P & W send at notice to: "All costumers" in the year 1994, that you need more than idle power to have any/some effect from the anti-ice systems.

Oluf (read all about it here: www.whistleblowers.dk )

Don't Hang UpI think the point being made is NOT so much about the descent profile but the exceptionally low temperatures that were encountered in the cruise. Many other AC encountering the same cold air mass had to drop height. Some people are considering that the extended cold soak of the fuel was then met by icing conditions during the descent.

Which is why this one-off event is so perplexing. There may well be guidance from the AAIB and manufacturers, there may well have to be another five years elapse before it happens again and more data is captured. It may never happen again.

obie2The 50 seconds I read was quoted earlier in this thread but, as I recall, not more than 60 seconds elapsed from loss of power to ground contact. Thinking time for a unique event that no one had ever encountered before? And yet some (I am merely an observer) criticise the crew for not taking out A/P and all sorts of other things. It is thanks to them that we can be discussing data and a very different AAIB problem.

The Sun
 

I see some columnist in The (soaraway) Sun has postulated his theory today....no gas in the tank? Is this to be discounted as pure Journo speculation....or is the investigation leaking again?

I'm sorry to read so many posts using the words engine icing and anti-ice in such an unsupportable matter regarding BA038.

Not for many years have these large fan engines used piped hot air to warm up the blades or vanes to keep ice off them. In the air they depend on the compression cycle temperature rise, centrifugal force and air air-velocity loads to shed accreted ice at low enough mass levels to not damage the engine internal parts or affect the engine surge stability.

Whilst tis true that the culprit ice does melt, its evidence on the engine that it leaves behind is unmistakeable to an investigator.

So to me the credibility of the engine teardown examination as well as the memory readouts pretty much eliminates this area still in consideration.

BA38s engines "Hesitated"
 

Dear lomapaseo,

You and a few others think, that I should wait for the AAIB or drop my theory of possible engine ice produced "hesitation"

OK, can you explain, why the FAA issued an AD on the 23. jan. 2008, only six days after BA38s "grass-landing" in order to:

"Prevent internal engine damage due to ice accumulation and shedding, which could cause a shutdown of both engines, and result in a forced landing of the airplane"

It was a 10 page AD called 2008-02-05 (or Directorate Identifier 2005-NM-263-AD) effective Feb. 27. 2008.
Valid for: Boeing Model 777-200 and -300 Series Airplanes Equiped With Roll-Royce RB211-TRENT 800 Series Engines.

Read it yourself, the improved procedure, calls for a more strict "engine anti-ice ON GROUND procedure" why this can avoid shut downs when airborne beats me. But it is the only change of procedures, since 17. jan.
2008.

So, at least the FAA thinks that engine ice might be the villain, why have the AAIB not commented on this AD.

Oluf

BA38s engines "Hesitated"
 

Dear lomapaseo,

You and a few others think, that I should wait for the AAIB or drop my theory of possible engine ice produced "hesitation"

OK, can you explain, why the FAA issued an AD on the 23. jan. 2008, only six days after BA38s "grass-landing" in order to:

"Prevent internal engine damage due to ice accumulation and shedding, which could cause a shutdown of both engines, and result in a forced landing of the airplane"

It was a 10 page AD called 2008-02-05 (or Directorate Identifier 2005-NM-263-AD) effective Feb. 27. 2008.
Valid for: Boeing Model 777-200 and -300 Series Airplanes Equiped With Roll-Royce RB211-TRENT 800 Series Engines.

Read it yourself, the improved procedure, calls for a more strict "engine anti-ice ON GROUND procedure" why this can avoid shut downs when airborne beats me. But it is the only change of procedures, since 17. jan.
2008.

So, at least the FAA thinks that engine ice might be the villain, why have the AAIB not commented on this AD.

Oluf

AD here. Page 2 and on.

http://www2.lba.de/dokumente/lta/2008/2008115.pdf

This is pure speculation from someone no longer associated with airlines, but I am afraid it may not be so easy to discard Mr. Husted's theory.

I note that the latest AAIB report says:

Posters have jumped to the conclusion that if the fuel flow increase was scheduled, then, if engine thrust did not increase, therefore the scheduled fuel flow increase did not happen. But, unless I'm missing something somewhere else, that's not what the report says.

Absent independent data from a fuel flow sensor showing that fuel flow did not increase, then I wonder if it's possible that fuel flow did increase, but that Mr. Husted's core icing prevented the engines from generating sufficient thrust?

If this were the case, I suspect there would be considerable egg on a lot of faces in the industry.

P.S.: In a fully flapped (40 deg) Cessna on a 3 degree approach at 500 ft, at engine idle I can't reach the end of the runway either. Please think about it before criticising the pilots.:E

I don't think that increased fuel flow would be prevented by core icing, if fuel flow was reported to be increased with no response then icing could be suspected, but fuel flow did not reportedly increase. As I understand the term, the engines did not hesitate, they merely carried on in accordance with the fuel they received. Regarding the AD, as far as I am aware, freezing fog was not present nor poor vis.

BA38s engines "Hesitated"
 

Dear Oldlae,

The definition of a cloud could be: "Freezing Fog" or just "Fog" and the visibility is always lousy in fog, and that is what the AD warns about.

Oluf

Oldlae:

No Oldlae, you are making an assumption. Nowhere in the report does it say that the fuel flow did not increase. What it says is that "the fuel
metering valves on both engines correctly moved to then fully open position to schedule an increase in fuel flow." You are making the causal assumption that since this occurred, and the engine did not respond, then the increased fuel flow did not occur.

As far as I can tell, the AAIB used those words because it does not have the data to show whether an increased fuel flow occurred or not.

To put it another way, if the AAIB knew for a fact that the fuel flow did not increase, they would have said the fuel flow did not increase, but that is not what they said.

If Mr. Husted's theory is correct, maybe an increase in fuel flow did occur, but the engine did not respond because of core icing.

Did fuel flow increase or not?
 

Sunfish,
....Presumably an increase of fuel flow without rotational acceleration would have led to higher engine temperatures.Wouldnt these show on FDR or QAR ?