BA056 JNB-LHR Incident.

[whattimedoweland]

I have heard different rumours (thats what this forum is about) that the
BA056 11.5.2009 returned to Jo'burg shortly after take off due to 'multiple' engine failure.

Can anyone in the know with any real facts give a more accurate account to confirm or deny this incident.

WTDWL.

[beamender99]

Incident: British Airways B744 at Johannesburg on May 11th 2009, two thrust reversers indicated open in flight

By Simon Hradecky, created Tuesday, May 12th 2009 19:05Z, last updated Tuesday, May 12th 2009 19:07Z
The crew of a British Airways Boeing 747-400, registration G-BYGA performing flight BA-56 from Johannesburg (South Africa) to London Heathrow,EN (UK), decided to dump fuel and return to Johannesburg after two thrust reversers were indicated unlocked after takeoff. The airplane landed safely about 90 minutes after takeoff.

Engineers determined that the indication was false, the thrust reversers had been properly locked in closed position.

The flight was initially postponed by 23 hours and later cancelled.

from Incident: British Airways B744 at Johannesburg on May 11th 2009, two thrust reversers indicated open in flight (http://avherald.com/h?article=4198598d&opt=0)

[Zulu01]

It's bigger than that - they nearly bought the farm:

From Av Com

by Romeo E.T. (http://www.avcom.co.za/phpBB3/memberlist.php?mode=viewprofile&u=1249) » Wed May 13, 2009 6:31 pm I have just heard some further info..........SCARY STUFF

from some of our technical "boffins" in the office today....results of the DFDR, crew interviews etc.

1)The B747 was very heavy and on rotate one of the engines flamed out, and another "rolled" back to idle RPM.....now on 2 engines only.
2)the thrust reverser light for 2 engines came on, and as per the design features of the B747-436, the leading edge devices retracted.....this is an auto response to prevent F.O.D. to the leading edge devices during reverse thrust operations..... thus even more loss of lift at a very critical phase of flight.
3)thru fast actions the captain was able to restore thrust to the engine that had "rolled back to idle".....but only after leveling off...or even descending doen to 35ft...35ft http://www.avcom.co.za/phpBB3/images/smilies/icon_eek.gif http://www.avcom.co.za/phpBB3/images/smilies/icon_eek.gif http://www.avcom.co.za/phpBB3/images/smilies/icon_eek.gif http://www.avcom.co.za/phpBB3/images/smilies/icon_eek.gif
4)the aircraft slowly accelerated to climb speed with the partially extended leading edge devices and only on 3 engines.
5)fuel dumping took 2hours
6)after landing the crew refused to take the same aircraft out again...and they "paxed" back last night
7)SACAA has impounded the aircraft at ORTIA where the DFDR has been downloaded to annalize the incident

[Juan Tugoh]

Very scary stuff, sounds like an appalling situation handled with some excellent awareness and fast smart thinking. :D

[Hotel Mode]

I'm not sure about the thrust loss, that certainly hasnt been mentioned in BAs release of DFDR data.

[suninmyeyes]

Those facts don't quite add up. I think you'll find a heavily laden 747 cannot get airborne out of JNB with a loss of 2 engines and also leading edge slats at VR.

LH once tried to takeoff from NBO on a 747 classic without leading edge slats on 4 engines and still didn't make it.

[ray cosmic]

fly around on 2 engines to dump fuel for 2 hours?
Sounds both insane and untrue. The rate of Jettison in the -400 with all pumps operating is 105000 kg/hr, so explain me how much fuel they exactly carried.

[wobble2plank]

Engines 2 + 3 gave spurious thrust reverser unlocked indications at rotate leading to an automatic slat retraction with associated loss of lift.

Crew handled the amber thrust reverse warning with full thrust and gear retraction with onset of stick shaker.

Aircraft flown away and returned to JNB after dumping fuel.

Excellent handling of the situation by the crew who contained an extremely serious incident.

As has been mentioned before a Lufthansa aircraft which tried to get airborne from NBO didn't make it when the LE Slats weren't deployed so it shows the quick thinking of those involved.

[M.Mouse]

The quoted piece above comes from AvCom topic - emergency in JHB now? (http://www.avcom.co.za/phpBB3/viewtopic.php?f=1&t=47484&hilit=BA+747)

The 'authoritative' postings from people who are clearly clueless would suggest it is somebody trying to impress that he has inside knowledge when in reality he hasn't. Gems such as 'Thrust reverser warning light' (no such thing on a B744) with another idiot explaining that a B744 can only dump fuel from the centre tank (it can dump fuel from all tanks).

I do also know the pilots didn't 'refuse to fly it back'.

[TURIN]

I am confused, surely the LE devices would extend again as soon as the craft got airborne.

From another thread...
Automatic Leading Edge Flap Retraction
Group A leading edge flaps are automatically retracted during ground
reverse thrust operation in order to improve structural life of the flap
panels. The function is armed when the airplane is on the ground and
the flaps are operating in the pneumatic mode.
Group A leading edge flaps retract when armed and engines 1 and 4
are placed in reverse thrust or engines 2 and 3 are placed in reverse
thrust. The flaps re-extended when the reverse thrust signals are
removed.


NOTE:
Thrust reverser operation is defined as reverse thrust
selected or airmotor brake released or gearbox unlocked
on a symmetrical pair of engines.



Not questioning the integrity of the reports, just asking the question that's all. :ok:

[wobble2plank]

M Mouse,

Sorry but my post was written entirely by me. Not by the source you claim. I have the full details of the incident. There was no un-commanded thrust reduction or engine shut down but the loss of the inboard and mid LE slats was enough to cause the stick shaker at 12 feet and a level off at about 40 feet.

Extremely scary stuff in a heavy 744 out of JNB.

Still, very well handled by the crew involved.

[TURIN]

Don't think he means you Wobble.

Zulu01? :suspect:

[spannersatKL]

Zulu01 I have nerer read such rubbish........clearly you have no idea of the interlocks in place to prevent leading edge devices retracting when not selected to so do!! !!! I assume on the take off roll the reverse thrust levers were not pulled, flapes not in landing range etc!!! Pure speculation and fantacy on your behalf!!!

[Hotel Mode]

clearly you have no idea of the interlocks in place to prevent leading edge devices retracting when not selected to so do!!

Thats the bit thats correct. The reverse amber did appear and the inboard and midspan LE slats did retract. Looks like another interlock is needed!

What didnt appear to happen was thrust loss.

[M.Mouse]

No I was not referring to you Wobble but the post by Zulu01 lifted from the AVcom website.

I have since learned that the statement ....."rolled back to idle".....but only after leveling off...or even descending doen(sic) to 35ft...35f'' is complete nonsense.

The leading edge slats DID retract at the same time as the reverser unlocked EICAS warning occurred.

It was a very unpleasant incident but was not as dramatic as the factually inaccurate posting from AVcom implies and was well handled by the crew.

[TopBunk]

Typically BA B747-400's take off from JNB at about 354 tonnes (ZFW about 232t + about 122tonnes fuel) for the 10:30 flight to LHR. This at about 15-20 deg C OAT and calm wind will require about 1.68-1.70 EPR from the engines, which is not short of full thrust.

Max EPR with packs off at that density altitude is about 1.74, ie the take off is pretty limiting, and frequently the EGT's will be about 740deg C (vs 785 max).

In those conditions, there is NO WAY that a Flap 20 take off will result in a successful conclusion with 2 engines not delivering thrust (with or without leading edge devices as expected).

There is a lot of bullsh1t here. As I understand it, there were spurious reverser EICAS messages, at the same time there were leading edge flap anomalies; but the engines still produced commanded thrust. What little excess thrust remained was applied, the gear retracted, and after at about 160'agl the leading edge devices re-deployed to the correct position.

Prior to that, stick shake activations had occurred at about 12'agl.

[gas path]

Well seeing as its now in the public domain!
Wobble2plank has it on the money!
It was not a reverser unlock! and on the subsequent landing it all did 'what it says on the tin'!
Engines 2 and 3 REV Amber (cowl position) within approx 15 secs of each other during the roll. As the aircraft was still on the ground this resulted in a command to the FCU's to retract the L/E flaps Group A. The reverser commands to the FCU's operate in pairs 1&4 2&3
The L/E flaps probably extended again as the a/c became airborne.:8

[Joetom]

Sounds like Wobble and Gas have many facts.

From memory, the LH at NBO had all L/E stowed, sad day for them.

Would like to know if subject aircraft had any/much history of REV ind problems with its engines ???
.
ASN Aircraft accident Boeing 747-130 D-ABYB Nairobi-Jomo Kenyatta International Airport (NBO) (http://aviation-safety.net/database/record.php?id=19741120-0)
.

[Romeo E.T.]

Wobble2plank and gas path...you 2 must be closer to the source than what I am.

as I mentioned on the Avcom website, I was on technical refresher today...course presenters are ex SAA B742/3 flight engineers, and being a BA franchise airline, we do get a lot of info handed down within the company....although "second-hand".

When our technical staff and our FSO relayed the sequence of events including the loss of thrust on initally 2 then restored to only one eng out, I believed their version of the story....

seems I may be wrong on those accusations, but it does still sound like the "reverser-unlock" and subsequent retraction of LE's close to or during rotate and the stick shaker activation still makes it a very scary event, and total "hats off/respect" to the crew for getting it safely out of that situation and to an uneventfull return to land.

[wobble2plank]

M Mouse,

Sorry about that then, I must read more carefully!

:}

[gas path]

From memory, the LH at NBO had all L/E stowed, sad day for them
Thread drift here but the LH incident was/is totally unrelated to what happened to the 56.
Now a bit rusty here but.....
In that case, the engines in those days were very 'strapped' for power especially at a place like NBO and bleeds off takeoff was reqd.
The F/E had selected the pylon valves (bleeds) closed after start and at the time there were no warning lights on the front P3 panel for L/E position/disagree. (amber and green). The trailing edges deployed, albeit slowly as the EDP's were producing pressure, but without the pneumatics the L/E flaps all remained stowed.
That indication light mod. on the P3 panel came about a result of that accident.

[h3dxb]

@Turin
I am confused, surely the LE devices would extend again as soon as the craft got airborne.

THX buddy for yr post, had my description only in german. U R right
Auto LE retraction is controlled by switches in the thrustlever assembly and at least 1+4 or 2+3 must be physically activated by moving the levers in direction REVERSE > 6 degrees

Strange post I guess ...:ouch:

[wobble2plank]

Quick update:

The stick shaker kicked in at 12 feet and due to the quick reaction of the crew advancing the throttles and getting the gear up 'sharpish' the stick shaker stopped at 40', no level off as mentioned in my previous post.

As the aircraft accelerated the LE slats redeployed at about 160'.

Nicely handled!

[Ibhayi]

Will somebody please explain what happened in terms for those not clued up on the jargon?

[wobble2plank]

On rotate out of Johannesburg the aircraft systems gave a spurious warning that the thrust reverser doors (Used on landing to assist in braking the aircraft) on engines 2 + 3 were unlocked (possibly open or deployed leading to the engine thrust being deployed forward not rearward).

A potentially dangerous situation as a thrust reverser deployment in flight, especially at low speed/low level can cause a disastrous departure from controlled flight! The system has three interlocks which should prevent actual deployment in flight.

The crew could not know what that actual deployment of the thrust reverser doors was, however an actual deployment would most certainly be felt by the flying pilot!

As a damage security system the 744 automatically retracts the mid and inboard leading edge slats to prevent damage to the slats from the thrust of the engine now coming forward. As JNB is a high airfield in hot conditions with a heavy aircraft these lift enhancing devices on the leading edge are vital, all take off and climb out speeds would be calculated using LE slats deployed. Loss of those, without quick intervention could lead to a stall.

The aircraft stick shaker is there to warn the crew of impending approach toward the stall. Thus, at the onset of stick shaker the crew selected full Take Off/ Go Around (TOGA) power, brought the landing gear up to reduce drag and flew the aircraft away from a potentially dangerous situation. Normal take offs are conducted at a 'flexible' power dependant on the conditions of the day to save on engine wear.

Excellently handled and I think I can see the next 6 monthly simulator check scenario now. :eek:

[gas path]

Excellently handled and I think I can see the next 6 monthly simulator check scenario now.
I can see an engineering solution coming out too, probably in the form of some wiring changes and an extra couple of relays!:8

Potentially this would affect all 744 operators as the A/F systems are all the same it's just the T/R modus operandi that differs!

[Wytnucls]

Not wanting to take anything away from the crew, but we are taught to keep the gear down in a near-stall close to the ground situation, until clear of terrain and out of stall airspeed. This is to prevent extra drag from gear door extension in a critical phase of flight and also if ground contact becomes unavoidable, it should happen with the gear down rather than in the middle of a retraction sequence.
Your thoughts?

[M.Mouse]

Thus, at the onset of stick shaker the crew selected full Take Off/ Go Around (TOGA) power, brought the landing gear up to reduce drag....

Certainly on the aircraft I fly the gear should not be moved during stall recovery because of the increased drag during gear retraction. Can you confirm that is not the case with the B747?

[CptRegionalJet]

I wonder it got airborne at all with that asymetric lift due to LE devices on one side retracted.The AA DC-10 crash at ORD comes to my mind.
I would have thought of a severe amount of roll to be encountered.
If the crew was able to recover that----hell of a job:ok:

[Carnage Matey!]

I think the slat retraction would be symmetrical.

M.Mouse - it's not a published procedure on the 744 to raise the gear in a stall situation but I'm sure more detail will be available through the usual channels shortly.

[wobble2plank]

CptRegionalJet

It was the LE slats on both sides that retracted due to 2+3 being both inboard engines. As you say though it could have been interesting if it had only been one reverser! [edit] I seem to remember that the system would retract both LE slats symmetrically irrespective of which engine was causing the problem to prevent asymmetric wing loading.

As to the SOP for retracting the gear I have to come clean and say I don't know as I don't currently fly the 744. However I would suggest that the drag caused during retraction could possibly even be less than when the gear is fully deployed judging by the number of wheels dangling down and their retraction sequence. At the time the desire to get the gear up and hence drag down to cancel the stick shaker would probably have been foremost. Especially if there was no suitable terrain below anyway.

Best to ask someone current on the aircraft.

[nil desperandum]

744 SOP is to leave the gear down in any situation where a positive rate of climb is not being achieved, (for example a Windshear Go-around). Only when a positive ROC is achieved do you select Gear Up.

[western bronco]

Hats off guys:D

That could have been horrendous from any airfield but out of there twice as bad!

[springbok449]

wobble2plank,

The drag would not be less during retraction because, if you select gear up, the landing gear bay doors have to open in order to allow for gear retraction, trust me those doors are massive, add that to the landing gear itself and it would cause way too much drag, so the last think you want to do in a situation near the stall or multiple engine malfunction on take off is to retract the gear...especially in JNB.

Bokkie449

[M.Mouse]

So there we have it Wobble has some accurate information but cannot leave it at that and proceeds to explain incorrectly the rest of the event.

Why cannot people just post what they KNOW to be factual?

[Kerosene Kraut]

So what would be BA's statement on said incident? If there's any.

[Litebulbs]

All the actions carried out by the crew proved to be effective, regardless of what any current SOP states. That is a fact.

[beatnik]

I'm asking this as a PPL and therefore as a non-B744 driver, but would the fact that the takeoff was after sunset have made it better or worse for the crew.

Obviously it was slightly less "hot" (but still high), but is it easier to run through options available only 12 - 40 ft off the ground during the day, or at night.

Are the instruments/warning lights clearer? Does it help seeing the ground in daylight, or is it all pretty moot in the timeframe they had to react?

[Thor Nogson]

All the actions carried out by the crew proved to be effective, regardless of what any current SOP states. That is a fact.

Without going into the detail, and without wanting to denigrate the (possible) actions of the crew in any way, isn't that the equivalent of saying anything that you do that doesn't result in a crash is effective?

The question should be whether they did actually retract the gear then, and if they did, was it the optimal reaction? It's a serious enough incident to warrant speculation, but we'll only know when the facts come to light.

TN

[Xeque]

All you professional guys out there - doesn't a story like this worry the hell, out of you (and the pax sitting behind you)?
You've done all the calculations, correctly set the aircraft up ready for takeoff according to weight, altitude, weather conditions etc. Are you not completely in control during the critical 2-3 minutes that follow?
When I push the throttle forward in my C152 and commit to takeoff I expect to be in total control for every aspect of the flight thereafter including an EFTO.
This story suggests that a computer (a machine of questionable integrity programmed by a nerd who might or might not have been having a bad day) decides that a major mechanical malfunction has taken place (when it hadn't) then retracts essential lift devices at the very moment they are needed most and all of this happens between 12 and 40 feet above ground. Whatever happened to PIC?
Thank God the crew were experienced enough to take corrective action. How many Third World crews would have been able to do the same or ended up splattered all over the airfield perimeter?

[CSman]

As an old B744 driver I say well done to the crew involved, forget about all the bullsh*t ,you kept the aeroplane flying ,no one was hurt, that is what aviation is all about WELL DONE

[Avman]

Thank God the crew were experienced enough to take corrective action. How many Third World crews would have been able to do the same or ended up splattered all over the airfield perimeter?

Not a very PC statement to make but I find myself agreeing with you. That´s why I choose very carefully who I fly with. It´s not by any means a 100% guarantee of course, but it does improve the odds by a few percentages.

[M.Mouse]

I'm asking this as a PPL and therefore as a non-B744 driver, but would the fact that the takeoff was after sunset have made it better or worse for the crew.

Obviously it was slightly less "hot" (but still high), but is it easier to run through options available only 12 - 40 ft off the ground during the day, or at night.

Are the instruments/warning lights clearer? Does it help seeing the ground in daylight, or is it all pretty moot in the timeframe they had to react?

After sunset usually the temperature will have dropped a little but whatever the temperature the performance calculations will have been based on that temperature.

In my experience at the stage it happened the pilot flying would or should have acted instinctively at the occurrence of the stick shake i.e. reduce the angle of attack as much as was possible at such low altitude simultaneously selecting full power, assuming any more was available.

Day or night the instrumentation and cockpit illumination is adjusted to a level to suit the conditions. They are clear and easy to read day or night for that reason.

There are no warning lights as such on the B747-400 except for the Master Warning/Caution light on the glare shield which illuminates when the level of EICAS (Engine Indicating and Crew Alerting System) warning message warrants it.

A reverser unlocked will normally be indicated by an amber 'REV' in an amber box above the relevant engine EPR (Engine Pressure Ratio) indicator and an EICAS message 'ENG REVERSER' will be displayed if a fault is detected. In the incident concerned I have no idea what the systems were doing nor which message(s) or warnings, if any, were triggered.

After rotation the handling pilot is flying by reference to instruments even having reduced the AoA I doubt looking out the window would have been much help but that is only my opinion.

Doesn't it worry you? All you professional guys out there - doesn't a story like this worry the hell, out of you (and the pax sitting behind you)?
You've done all the calculations, correctly set the aircraft up ready for takeoff according to weight, altitude, weather conditions etc. Are you not completely in control during the critical 2-3 minutes that follow?
When I push the throttle forward in my C152 and commit to takeoff I expect to be in total control for every aspect of the flight thereafter including an EFTO.
This story suggests that a computer (a machine of questionable integrity programmed by a nerd who might or might not have been having a bad day) decides that a major mechanical malfunction has taken place (when it hadn't) then retracts essential lift devices at the very moment they are needed most and all of this happens between 12 and 40 feet above ground.

Factually incorrect. For whatever reason the aircraft sensed that a reverser(s) was or was about to be deployed and retracted some of the LE devices as per design. The cause was a fault somewhere not the rather glib assertion that an individual having a bad day during the design phase made a mistake many years ago.

Whatever happened to PIC?

He is alive and well. He may or may not have been the handling pilot.

Thank God the crew were experienced enough to take corrective action. How many Third World crews would have been able to do the same or ended up splattered all over the airfield perimeter?

Assuming a Third World crew, as you so condescendingly refer to them, had legitimately qualified for their positions and had had the benefit of the level of thorough training many of us enjoy I am sure they would have been just as successful as us superior First World pilots.

The difference and problem is that nepotism and bribery too often influences the selection criteria and training standards are poor in far to many airlines run by bankrupt and corrupt countries.

[llondel]

After rotation the handling pilot is flying by reference to instruments even having reduced the AoA I doubt looking out the window would have been much help but that is only my opinion.

A question - if you're at 35ft, flying by instruments, is the PNF looking out of the window for obstacles? I appreciate that anything but a straight line is going to be problematic at that altitude. Obviously the problem manifested itself when there was still runway in front, but there wouldn't have been much time to react, get the engines spooled up and gain a bit more altitude. (I know it's several seconds from idle to decent power, what is it from typical flex t/o power to TOGA?)

[Carnage Matey!]

A question - if you're at 35ft, flying by instruments, is the PNF looking out of the window for obstacles?

I very much doubt it. More likely looking in trying to work out WTF is happening.

Obviously the problem manifested itself when there was still runway in front,

In my experience not very much. You are often into the last 900m of runway at JNB when you rotate, with a ground speed in excess of 180kts.

I know it's several seconds from idle to decent power, what is it from typical flex t/o power to TOGA?

If there is any derate at JNB it's usually pretty small. I'd be surprised if it took more than 5 secs to go from derate to max power.

[Caudillo]

Thank God the crew were experienced enough to take corrective action. How many Third World crews would have been able to do the same or ended up splattered all over the airfield perimeter?

Bit of a jump in the logic there don't you think?

You rightly praise the sufficiently experienced crew for pulling themselves out of a hole.

Then you ask how many Third-World crews might have managed the same.

I'm not sure where the third world bit comes in, unless you equate it with inexperience?

[Starbear]

Xeque
Are you not completely in control during the critical 2-3 minutes that follow?A more rational answer to your query is yes. Yes, it is worrying for the simple reason that this appears to be another one of these things that was either completely unforseen at design stage or more probably, the likliehood of such an occurrence was deemed to be so remote as to not require any additional protection against.

If you look carefully at what happened here, there were two simultaneous and erroneous indications of thrust reverser deployment. I will leave it to the designers and mathematicians to give the odds on that happening. But happen it did (based on these "reports" so far) but according to an earlier explanation it also required the a/c to be "on ground" though air/ground sensors, so further reducing the chances of this event. So it looks like all things conspired in the worst possible sense against this crew but they have managed wonderfully to rescue a dire unforseen event.

It is a fact of aviation life that all professionals strive to do everything within their power to do things correctly and properly for every flight but that there will always be something new to catch one out. It has always amazed me how some very old aircraft types still have bulletins, both technical and operational, being issued donkeys years after all glitches should have been ironed out.(I am not talking about wear and tear here)

I could go on an tell the tale of a B737-200 where all flight and ground spoilers (was 8 or 10?) deployed inflight when the speedbrake was selected. Only flight spoilers (4 off) should have deployed and it was "impossible" by design for the ground spoilers to so do. Yet they did and at relatively low height. That was over 30 years ago but I will never forget that Captain's face during the debrief. But I won't bore you with that story now.

[Avman]

I'm not sure where the third world bit comes in, unless you equate it with inexperience?

Not so much inexperience but training, culture, training, discipline, training, training, and training!

[scarebus03]

In several posts it has been noted that the t/rev EICAS indications were spurious. If that is in fact the case why did the l/e devices retract?

Well done to the crew however I'd like to see the report before the word spurious becomes the norm like on the Airbus

Brgds
SB03

[M.Mouse]

Plainly the reversers did not deploy. They either unlocked or the system sensed they were unlocked when they weren't.

The leading edge slats did what they are designed to do when reversers are unlocked. In other words the LE salts behaved correctly for the sensed condition, actual or otherwise.

[Swedish Steve]

Plainly the reversers did not deploy. They either unlocked or the system sensed they were unlocked when they weren't.

There is a prox sensor on the lock, and another at the top left of the cowl. If either is 'far' then the amber REV will come on. It is extremley unlikely that the reverser unlocked. Most probable is that the cowl closed sensor went to 'far'. I have had this happen when a flex drive sheared between the motor and the number 1 gearbox. The reverser doesn't move, but the top left corner of the cowl flexes just enough to bring on the REV indication. Unfortunately at present on a B744 this gives a signal to the inboard l/edge flaps. I expect a mod to come out to need the unlocked sensor to indicate 'far' as well.

[glad rag]

Thanks, Swedish Steve, for that concise description of system indication. :ok:

[alouette3]

Avman, et al:

I am just a lurker on this side of the forum.But going by your statements,the crew at Buffalo,NY was inexperienced, and had inadequate training. So does that make the US a backward Third World culture with folks who can bribe their way to a pilot's seat?
Not taking anything away from the BA crew, but it is sometimes sickening to watch my associates from the First World, strut around like those Magnificent Men in Their Flying Machines.
Going back to lurking now.
Alt3

[Danimal]

I had a similar not so dramatic incident with on a Air China flight out of PEK in a 744 three years ago. As a pax. Plane was already accelerating pretty much, when it made an abort. Pretty hefty and impressive.
You could imagine that there was no decent info why and what. After the runway was cleared and a/c parked, we waited and I noticed mx in and out and on one of the engines. Found one of the pilots and he explained in english, that the Amber light came just after the acceleration. Great they could abort.
Of course, sensor issue, rev locked and after the usual paperwork back to runway.
Great work, but nobody except me knew really what it was. This is China. And a very new 744.
Danny

[Litebulbs]

Thor,

The action taken by the crew was successful. You have the result and you can try to simulate other actions to try to prove if, or if not, the actions taken were optimal.

Given the exact same circumstances, follow exactly what the crew did. We know that it works. Who knows if leaving the gear down would be safer? What would you do? If you were unlucky enough to be in the exact same position, would you back simulation or an actual event?

[Akali Dal]

Great job by the BA pilots.........enjoy the time off.

As for Danimal's account; sadly, there were no " fans " to crow loud and clear about the great job the Air China crew did!

The BA cre sure have die hard fans like wobbly and ilk.

[ALK A343]

Well done BA crew,

I find it very disturbing that we dare to judge the BA crew and their actions in avoiding a disaster from the comfort of our home having all the time in the world to micro-analyze.
They reacted according to their natural instinct increase thrust and clean up. Whether it was the most optimum reaction or not, who are we to judge?

Fact is, they saved the day with very little time on their hand. I know the feeling of going down a long runway at night on a quad with a lot of heavy metal behind you, there really is not much time to think of every possible outcome to a situation or what might be the best way to sort a problem. All you can do is, fly the plane and use airmanship.
That's what they did. That's what so many crews all over the world do every day, in every country (third world or not). The fact that we don't make the news headlines everyday just proves it.
Once again very well done BA!
My utmost respect for the crew! :D

[stilton]

No question this crew did a brilliant job (gear retraction notwithstanding)


No one seems to be questioning Boeings design logic here however. I understand the reasons for the auto slat retraction on landing with reverse thrust activation.


What I dont understand is why this system does not lock out above say 100 knots.


No matter what your engines are doing none of us want our slats auto retracting as we are approaching or are after rotation speed.


Seems an easy fix ?

[SMOC]

What I dont understand is why this system does not lock out above say 100 knots.

Because you will be landing and selecting reverse above 100kts, so therefore the LE will need to retract as per the design.

Better to lock out with the fwd thrust levers in the take off range.

[R04stb33f]

Quick question...

At such a low altitude... stick shaker going...
Gear up is selected. How long does it actually take from Gear up select to actual gear up? :ooh:

[Joetom]

A few points.

1. Gear up selection will increase drag for a little while, but very soon after drag will be back where it was before and then a big reduction in drag as its all stowed away, times like this you want all the 1 and 4 EDPs and demand pumps plus all eng bleeds in working order, strange fact is the operation of the L/E will be using bleed air that the demands would like very much at that time
.
2. Gear up selection will also give a little pitch down effect, may of been a good thing on said flight.
.
3. Leaving gear down in case ground contact is made may be good in some events like a G/A, leaving gear down in this event may or may not have been good, had gear of made contact again, story could have a different ending.
.
End result was very very good, well done to all.

[M.Mouse]

Here we go with blow by blow analysis of what would or would not have been the best course of action before we know EXACTLY the sequence of events.

Whether they raised the gear or not I have no idea but in light of the above post if you ever watch a jumbo retract its gear it is not by any means a rapid process. It is a fact that raising the gear increases drag when the gear doors are opened during the retraction sequence and so the statement above that the aircraft would benefit from the ultimate drag reduction is fanciful if you have crashed in the meantime.

The basic facts are known, the crew flew the aircraft to a satisfactory outcome and speculation about what they should or should not have done is a waste of time until the full report is eventually published.

[Carnage Matey!]

IIRC there's rising ground beyond the end of the runway at JNB. If you can't climb with the gear down I'd say it's better to take a temporary sink over the flat ground and get the gear up than dogmatically stick to SOP and fly level into the approaching terrain!

[L337]

At JNB as you get airborne, in the dark, the end of the runway is already behind you. Typically V2 is 180kts. Ground speed is well over 200mph. With the nose rotating to 13 - 15 degrees, all you can see out the window is inky blackness. So it is very quickly onto instruments.

Simply put, you are out over the bush at about 100' doing 195kts, climbing. It is an interesting debate about the gear. The 744 had not stalled. It had a stick shake. So was close to a stall. With the gear now moving up you get a drag increase from the doors. No lift reduction. The gear does not affect the lift the wings are making. With the engines being fire walled, the drag increase is more than accounted for. The assumption in that statement is that they would have been using reduced thrust. It would be very unusual if they were using full power at JNB.

Wheels up or wheels down sinking into the veldt at 240mph is catastrophic. So the only reason not to raise the gear is the one of the doors, and the resulting drag increase. We could sit and debate endlessly whether the wheels should or should not have been left down, but what we do know is that the gear came up, and they flew it away to a safe outcome. So on some level, if not on all levels, the crew made the correct call.

[edmundronald]

There seems to be considerable debate about whether it is better to increase drag temporarily by raising the gear, or not - maybe this issue is deserving of simulation as an answer cannot be arrived at intuitively?

Edmund

[FullWings]

I think this discussion shows that you can't write SOPs for every conceivable occurrence and that Airmanship is thankfully still alive and well in some quarters.

I'm sure at the back of their minds was the possibility of needing to rapidly shut down an engine if it actually went into reverse (very unlikely, even at that stage, but...) and having the gear down at that point wouldn't be a great help.

The same sort of thing could be said of the BA38 double engine failure on short finals: the QRH is written assuming that there's reasonable time available for relights, not that you're going to be on the ground in 40secs...

[lomapaseo]

There seems to be considerable debate about whether it is better to increase drag temporarily by raising the gear, or not - maybe this issue is deserving of simulation as an answer cannot be arrived at intuitively?


It's a simple calculation in a performance deck if you have access to somebody who knows

[Sygyzy]

In the windhsear and gpws situation greater minds have determined that there should be no change in configuraton until the warnings have stopped and you're safely climbing away, gear doors produce drag...so 99% of the above is :mad:. Some infromed comment would be good...just occasionally

[FullWings]

There seems to be considerable debate about whether it is better to increase drag temporarily by raising the gear, or not - maybe this issue is deserving of simulation as an answer cannot be arrived at intuitively?It's a simple calculation in a performance deck if you have access to somebody who knows

...and can run the figures with 2/3 of the LEDs retracted... :eek:

There is the possibility that they might have needed to accelerate in ground effect before climbing, given that they were close enough to max AoA in the config. they found themselves in to trigger a stick shake. A few seconds thought (which is all they had) might have led to the conclusion that this would be easier/more effective with the wheels up?

In the windshear and gpws situation greater minds have determined that there should be no change in configuration until the warnings have stopped and you're safely climbing away, gear doors produce drag...so 99% of the above is...
I think leaving the gear down in those scenarios is more to do with possible ground contact during the recovery than with drag. If you give the terrain a glancing blow with the undercarriage rather than the engine pods, it may produce a better outcome. Keeping the wing the same section allows for a better initial ROC in the GPWS instance and a better climb rate/gradient in windshear.

[Propellerhead]

But the take-off sop is positive climb, gear up. So they may have already selected gear up before the stick shaker activated, or at the least have called for it's selection. They were faced with an unusual situation and dealt with it very well.

[stilton]

SMOC, your solution (locking the LEDS) with the thrust levers in the forward position seems a good one.


Can anyone speculate as to why this is not done ?

[Sir Richard]

Perhaps because it would require one more layer of interlocks (and associated drills) which may cause problems when you wish to retract the flaps/slats after a normal takeoff ?:rolleyes:

[L337]

Sygyzy: In the windhsear and gpws situation greater minds have determined that there should be no change in configuration until the warnings have stopped and you're safely climbing away,

Um, No windshear. No gpws. They had a stall warning. Out over the bush in Africa. Doing 195kts. Climbing. They selected full power.They climbed away and landed with no trauma.

I would like to think that my comments were informed. I am a 744 Captain. I have over 5000 hours on the beast. And, to date, have managed not yet kill myself or any passengers. I am more than happy to admit my view of the incident is wrong. But your erudite post has yet to convince me.

[M.Mouse]

Presumably a stall warning indicates the aircraft is approaching the stall. What are the standard stall recovery actions on the BA B747?

My manuals for the B777 categorically state do not alter the aircraft flap or landing gear configuration so does the B747 uses different procedures?

[bobmij]

My immediate concern is how the false reverse signal was generated on two of the engines. If this can be identified accurately and resolved then hopefully it renders the speculation about gear doors at 200 feet redundant. I would say RFI is a strong contender.

[M.Mouse]

The stick shake occurred at 12.5 feet radio.

[Gigajoules]

L337

Out over the bush in Africa.

Not too much bush at Joburg mate. But, as a matter of interest, what role did the runway they took off from play in the positive outcome of the event? The ends of the 21's appear to be more forgiving than those of the 03's.

BTW, I'm no pilot, only a humble chemist.

[Carnage Matey!]

It was a departure off the 03s.

M. Mouse - what the B777 manual says is irrelevant. The B744 has a procedure for stalls and a procedure for double engine failure, but not one fir both events simultaneously on departure. It would appear in this case the crew decided that cleaning up in case of the need to shut down one or more engines with deployed reversers was the priority over the stick shake and that demonstrably worked. The aircraft will fly just fine on the threshold of the stick shaker. It won't fly with two engines out and the gear down. Think Concorde.

[FullWings]

It would appear in this case the crew decided that cleaning up in case of the need to shut down one or more engines with deployed reversers was the priority over the stick shake and that demonstrably worked. The aircraft will fly just fine on the threshold of the stick shaker. It won't fly with two engines out and the gear down. Think Concorde.
Makes a lot of sense. It probably wouldn't have taken much of a reduction in pitch attitude for the aircraft to make ground contact and I expect that would have been beyond the end of the paved surface... :ouch:

They seem to have ended up in a similar situation to the EK flight out of MEL, i.e. passing the end of the runway in an aircraft almost too heavy to fly in its current configuration, only for completely different reasons. At that point, SOPs get put to one side and as our colleagues from the USA would say, the only option left is to "fly the airplane". Well done.

[L337]

This is a direct quote from the Boeing 744 QRH.

Procedures Beyond the Scope of the QRH

Introduction:

It is rare to encounter inflight events which are beyond the scope of
established non-normal procedures. These events can arise as a result of
unusual occurrences such as a mid-air collision, bomb explosion or other
major malfunction. In these situations the flight crew may be required to
accomplish multiple non-normal checklists, selected elements of several
different checklists (applied as necessary to fit the situation) or find little
or no specific guidance and need to rely on their own judgement and
experience. Because of the highly infrequent nature of these occurrences,
it is not practical or possible to create definitive flight crew procedures to
cover all events.

To have Engines 2 and 3 REV "Amber" (unlocked) warning lights, then have the inboard and mid LE slats retract, and then have a stall warning at rotate is beyond the scope of the QRH. This scenario is not something that forms part of any check or training in the simulator. The situation required them to rely on their own judgement and experience. There is no definitive flight crew procedure for the combination of events they were presented with.

They had no time to diagnose, they had no time trouble shoot, they were straight into "mitigate".

As we know they elected to raise the gear. They also landed safely, and nobody got hurt.

[johan_jnb]

L337 - Simply put, you are out over the bush at about 100' doing 195kts, climbing.

Sorry mate := but there is a town called Kempton Park which is north of 03L perimeter, starts around 500m from threshold - stretching 7kms north and around 4-5 kms either side of flightpath out. I live in this town and believe me, this incident has made quite an impact on thousands of aviation/JNB-airport employed people living in this town...:\

[L337]

Dear me. I retract the word "bush" and would like you all to insert "Kempton Park" in it's place.

The point I was trying to make is that you are not over the runway. So if the you touch down again you are not going to "bounce" off a nice friendly runway. But bounce into "Kempton Park".

[Captain Airclues]

The stick shake occurred at 12.5 feet radio

It stopped at 32.8 feet radio.

[TopBunk]

The stick shake occurred at 12.5 feet radio It stopped at 32.8 feet radio.

But the key question is what was the time betwen the two heights? I speculate that it was looooonger than normal.

Also, I believe that the raising of the gear resulted in the air-ground logic switching to Air mode, which resulted in the LED's driving to the normal positions by 160ft radio.

It just may be that raising the gear was a superb decision that guaranteed the successful outcome, much as raising the flaps to 20 greatly assisted the outcome for BA38.

[Da Dog]

M.Mouse said

Presumably a stall warning indicates the aircraft is approaching the stall. What are the standard stall recovery actions on the BA B747?

My manuals for the B777 categorically state do not alter the aircraft flap or landing gear configuration so does the B747 uses different procedures?

L337 has beat me to it with a fine explanation:D

Perhaps if you were desperate to know the answer to this question, you could have asked on the BA section of the BALPA forum where there is a long running thread on the JNB incident or indeed the tech part of said forum.

Or perhaps you were afraid that such a question could potentially be observed as a slight to the actions of the crew on the day!

[Joetom]

The DFDR will make interesting reading indeed.

Would guess the L/E waited for gear in air mode via the tilt prox sensors/logic, but guess it could be gear leaver position or position of gear.

Question, when L/E deploy, does lift reduce in the early stage on the 747, I would guess it does ? anyone know ?

[M.Mouse]

Or perhaps you were afraid that such a question could potentially be observed as a slight(sic) to the actions of the crew on the day!
Da Dog

At no point have I criticised the crew and nobody has actually confirmed whether the gear was raised immediately or not and if it wasn't at what point it was raised. It may well be the case that the stick shake caused them to leave the gear where it was and they then raised it when the stick shake stopped. Plainly whatever the crew did worked.

I do not subscribe to the view that they would have had sufficient time to analyse the situation, decide that they MIGHT have to shut down two engines, and that raising the gear while near to a stall was the lesser of two evils.

The BALPA forum consists of a thread almost entirely composed of unqualified congratulations so hardly the place to discuss the merits of various courses of actions but then it made your attack easier.

Full Wings said:Makes a lot of sense. It probably wouldn't have taken much of a reduction in pitch attitude for the aircraft to make ground contact and I expect that would have been beyond the end of the paved surface...

So raise the gear, temporary increase in drag, lower the nose to maintain airspeed, er..........

I'm off. I will just have to learn to blindly praise every perfect crew before the facts are known rather than try and learn from the incident whether anything done was less than optimum, albeit successful, just in case I am faced with the unthinkable which, as has been pointed out, is outside the scope of any known procedure.

[Da Dog]

M.Mouse,

The point I was trying to make was that, If you had asked the question I referred to on the BALPA forum I am 100% confident that you would have got a swift and concise answer, instead you elect to labour the point on an open, anonymous forum.

I can't think why.

I'm off have I touched a nerve?

[GS-Alpha]

I have as little idea about what actually happened as the next guy. I am simply glad this incident did not turn into a nasty accident.

Also, I believe that the raising of the gear resulted in the air-ground logic switching to Air mode, which resulted in the LED's driving to the normal positions by 160ft radio.

Surely you would be unable to raise the gear (without using the over-ride) if the air-ground logic was still in ground mode.

Were the REV indications only present once airborne, or did they show during the takeoff roll? It could be that the inboard and midspan LE flap groups retracted during the takeoff roll, but then re-deployed once the gear tilted as it got airborne? Pneumatic movement of the flaps is relatively quick, but would still not be in position for a short period of the initial airborne time (during which the stick shaker would likely activate).

[M.Mouse]

The point I was trying to make was that, If you had asked the question I referred to on the BALPA forum I am 100% confident that you would have got a swift and concise answer,

A swift and concise answer on the BALPA forum? I am still laughing at that one.

have I touched a nerve?

Nope. Just when attacks get personal it is time to go.

[Da Dog]

I am sad for you M.Mouse that you hold your work colleagues in such low esteem, I know of many high caliber trainers who would have been happy to answer your question either in public or with a private message.;)

However I suspect you already knew the answer;)

[Swedish Steve]

Were the REV indications only present once airborne, or did they show during the takeoff roll? It could be that the inboard and midspan LE flap groups retracted during the takeoff roll, but then re-deployed once the gear tilted as it got airborne?

The auto retract of the l/edge flaps is only armed on the ground. Therefore when the aircraft became airbourne this signal from the Thrust Reverse relays would have been lost and the l/edge flaps would have deployed again.

[gas path]

About 10 secs for L/Edge flaps to transit, and (from memory) about 16 secs for the gear to (physically) transit. (a little bit longer for the EICAS indication).:8
GS-Alpha see post 17:ok:

[Carnage Matey!]

M. Mouse - have you flown a jumbo or other heavy four engined aircraft? Perhaps you are used to flying a twin around where the potential loss of 50% of your thrust is no great problem. You don't need me to tell you that it's different in a jumbo. You are implying the crew responded in Pavlovian fashion, raising the gear simply because that's what they always did with no thought I'd analysis. I suspect any competent 744 crew on seeing 2&3 rev amber after V1 can make a pretty good snapshot call as to what the biggest threat to the aircraft was. If you had two unreliable engines on your 777 after take off would you faff around with a T-DODAR trying to work if raising the gear would help I'd hinder?

[TopBunk]

Aircraft due to leave JNB later this evening to ferry back to LHR. Both nos 2&3 reversers are/will be locked out!

[Sir George Cayley]

Let a just culture prevail:ok:

Let's not rush to judgement or excessive praise, and take the 'no blame' route.

That said, if anyone can let me know the tail number of a/c in question I think I'll let it do a few sectors without me!

Sir George Cayley

[4PW's]

I read PPRuNe in the hope of learning what I didn't know I did not know. And whenever I am lucky enough to find the limits of my knowledge before they bite me, I return to my company issued Boeing 744 CD-rom, a poor cousin to the erstwhile manuals.

I also read PPRuNe in the hope of re-learning what the passage of time has caused me to unwittingly and unwillingly forget. There's been a lot of forgetting going on in my overfull, greying head lately.

A few critical points have been taken from this very important thread:

One is the undeniable fact of it being populated by some very testy and apparently uneducated people on the matter of aviation who seem uncommonly keen to discredit tried and true procedures, to question proper process, or to nit pick well worded posts written by highly experienced pilots commiting the inexcusable crime of not naming an obscure and forgettable grouping of dim lights he has overflown on countless departures over the wider bush that is Africa.

Another is that the BA036 crew did an outstanding job.

Most importantly, my thirst for knowledge has been reinvigorated by a sense of self preservation. Fate is the hunter, and though I know the B744 airplane well, I don't know it as well as I'd like. Given it is my chariot in the workplace, I am forced to review my training in the case of being faced with the unthinkable.

I don't know how this incident would have transpired were I on the flight deck any more than I know how this afternoon's flight will ultimately work out until the brakes are set to park on the second and final stand.

Anything could happen, according to Boeing.

Which is sufficient reason to review my CD-rom, hateful disc of plastic that it is; to rely not on prayer but experience, training and a cool head, and to hope that my clear thinking cap with its well receded hairline is firmly latched if and when events become as unpredictable as they did for the BA crew departing Jo'berg.

[BarbiesBoyfriend]

PW

Well said.

There, but for the grace of God, go us all.

[Globaliser]

That said, if anyone can let me know the tail number of a/c in question ...G-BYGA? According to Heathrow & Gatwick Airport Movements (http://www.lhr-lgw.co.uk/) it went out on 10 May but didn't arrive back on 12 May.

[Willit Run]

I would be willing to bet that the gear retraction was in progress when the stick shaker was activated. ONce you notice an increase in altitude from the baro and radio, up comes the gear!

I have seen some mind blowing wierd things happen when moisture condenses on the logic cards. Cool avionics, then a blast of hot humid air , condensation happens.

[BOAC73]

How much are you prepared to bet??
Group A retracting on the take off roll and stick shaker as soon as air/ground sensing signals weight off wheels.
B73

[i sit in the back]

Ladies &/or gentlemen, there's a part of this story I've not seen mentioned here yet that happened after the initial emergency was over and the aircraft was safely up in the air.

I'm not prepared to say owt yet until I'm sure I won't be dropping someone in deep poo, but do keep an ear out for something that took place before the aircraft landed again.

As an aside, it's nice to see that you professionals can bitch and snipe at each other the same way members of music, photography and motorcycle forums do.

Cheers all,

A fare paying passenger.

[Joetom]

A wild guess to i sit in the back on your 1st post, aircraft headed for London as is normal on that route, after some time, Joburg was selected as next landing, fuel was off loaded during flight, aircraft then landed back at Joburg, appears a great job was done by all.

But if you know different, please tell !

[Da Dog]

I can't wait for this.............. spill the beans then sit in the back. The FDR and CVR have been back in the UK for a week, what do you know that BA/CAA don't???:mad::mad::mad:

[jimpy1979uk]

I see an Emergency AD coming out as a result of this. From all the posts looks like the aircraft did as designed. Well of course except for it happening in the wrong flight phase!

I appreciate also the reason behind the thrust rev amber indication needs to be fully investigated but the config change to the aircraft is the more pressing issue.

I would imagine a interim measure which would call for the deactivation of the auto flap function for the LEDs then in future a modification that would incorporate throttle lever position into the logic that the FCUs use for the auto flap function. But both of these would take some time to produce the necessary Service Bulletins.

As an engineer I could see a short term fix to prevent the change in config that this aircraft suffered from and that would be to arm the alternate flaps during the take off roll. Then once in the air deselect and operate the flaps normally.

[Captain Airclues]

jimpy

Would it be possible to programme the FCUs so that the auto function of the LEDs is only active when either flap 25 or 30 is selected?

Dave

[hautemude]

:E Any chance you could tell "I sit in the back" that he has failed his probation on the grounds of being ludicrous and ban him.

[jlreate]

Regarding the issue of the drag effect of the landing gear doors opening up during gear reatraction, I think that many people are unaware of this old, very similar, incident of Olympic Airways back in the 70s with the 747 classic.

On 12-8-1978 the OA411 flights from Athens Hellinicon (LGAT) airport experienced an engine flameout (engine two) during takeoff (at v1).
Additionally even though the takeoff procedure included the use of "water methanol injection" providing additional thrust during the very hot Athens august afternoon, due to cockpit miscommunication, the flight engineer turned off the injection just around V1.

The airplane eventually took off at Vr at the end of the runway just barely managing to pass the first hill (209ft) at 215ft (climb rate less than 200ft/min). During climb, engine 3, also suffered damage and become inoperational.
Under pilot's orders, the landing gear was not retracted due to the fear of drag from the huge landing gear doors opening. This was against company SOPs.

He continued on a level flight aiming for the nearest uninhabited hill near Piraeus but the flight engineer did manage to get a bit more power, thus increasing IAS and letting him reach the sea where he began dumping fuel and eventually retracting the landing gears performing a successful go-around.

Boeing did run the scenario many times in simulators all resulting in a crash ...

[NSEU]

If memory serves me correctly, it was British Airways which was involved in a similar incident many years ago.

A foreign object (manual?) had been left just forward of the thrust quadrant prior to departure. When the TOGA switches were pushed, the thrust levers advanced and the reverser knobs struck the object pushing them upwards.

There is a mechanical interlock which prevents the reverse levers moving upwards to reverse idle with the forward thrust levers more than a few degrees from idle. However, the reverse levers do move upwards a little bit (6 degrees or so). This is enough to trigger the first set of switches for reverser activation (and the LE flaps). Or rather, it used to be. An Airworthiness Directive and an associated Service Bulletin (SB 747-27A2356) was raised to modify/change some components to make the activation of this first switch set occur at 10 or so degrees rather than 6 degrees. The reverser levers will not physically move to 10 degrees with the forward levers out of idle.

Can't find the link I was looking for, but the following is related to this incident:

Airworthiness directives: Boeing, - Federal Register, November 25, 1998 (Nbr. Vol. 63, No. 227) - vLex (http://regulations.vlex.com/vid/airworthiness-directives-boeing-23432696)

Rgds.
NSEU

[Pinkman]

Instead of adding further complexity to the system why not just lock out the L/E auto-retract feature? It's there to prevent FOD on landing... how often does that happen in real life and how does that risk compare to what we have just witnessed in terms of likelihood and consequence? Of course it would mean someone actually getting off their bum and doing a PROPER walk round prior to the next departure....

Pinkman

[Old Aero Guy]

FOD isn't the primary reason for LE retraction with reverse thrust. The main concern is fatigue due to exhaust impingment on the LE while in reverse.

[lomapaseo]

Old Aero Guy

FOD isn't the primary reason for LE retraction with reverse thrust. The main concern is fatigue due to exhaust impingment on the LE while in reverse.

That makes a lot more sense than FOD. Seeing as it's pretty rare to have enough reverse efflux to lift an object as high as a LE slat except in the rarest of conditions.

[Pinkman]

I stand corrected!

[Will Fraser]

The way I see it, LE slats are lift enhancers. If Reverse is selected, I think extra lift might be unnecessary, even counter productive. Stowing all lift enhancers seems a reasonable thing to do when your goal is to slow down. Leaving drag devices deployed likewise seems correct. (Flaps and spoilers).

[noblues]

Imagine the scenario -

On rotation you get the stick shaker and two amber R's (inidcating you have two unlocked reversers).

The crew dont know the inboard and midspan LE devices have retracted ..

It would be extreemly tempting to assume the amber R symbols above the EPR are the problem and call for an engine shutdown ...

The crew did extreemly well ...

[banana head]

The way I see it, LE slats are lift enhancers. If Reverse is selected, I think extra lift might be unnecessary, even counter productive. Stowing all lift enhancers seems a reasonable thing to do when your goal is to slow down. Leaving drag devices deployed likewise seems correct. (Flaps and spoilers).

See it any way you like, but the design purpose of the inboard and mid-span LE devices retracting with reverse selected is to prevent fatigue on said devices. It was never designed as a method lift dumping, at which it would actually be of very limited use (consider the angle of attack of the wing after touchdown).

Imagine the scenario -

On rotation you get the stick shaker and two amber R's (inidcating you have two unlocked reversers).

The crew dont know the inboard and midspan LE devices have retracted ..

It would be extreemly tempting to assume the amber R symbols above the EPR are the problem and call for an engine shutdown ...


A point that cannot be stressed enough. It's all very easy to look at this incident with hindsight and suggest you or I would have acted differently (ie gear up or not) - but in a time limited situation I think they did a fantastic job of prioritizing the flying of the aircraft. Kudos to them.

[HarryMann]

The way I see it, LE slats are lift enhancers.

No, not exactly!

Not in the way that TE flaps are.

They principally extend the lift-curve-slope to higher incidences, but in themselves (at a given incidence) make little difference to lift

Thus at any given incidence, ground incidence in this case, as said, their retraction would make no appreciable difference

[Will Fraser]

Boeing 727, Cleveland, crew forgets LE slats on T/O, all dead. No difference?
The shaker on this recent T/O? Explain.

[HarryMann]

Will

Please read what I said carefully... !

AT A GIVEN INCIDENCE

To get the extra lift you have to increase incidence - beyond the max (or stall) incidence without them.. not the case with TE devices

So in themsleves they don't increase lift, but allow for higher incidences without flow breakdown.

The stick-shaker will vary with incidence, depending on the LE device position

Take the Barajas incident... the pilot pulled a (wing) incidence at rotation taking the aircraft into the regime requiring LE slats. They were not deployed -> stick-shaker -> without reduction in incidence -> approach to stall, loss of directional control -> stall. Maybe, if he had taken a less aggressive approach, possibly, he could have fown it off on the shaker, rather than way above. It was the extreme incidence requiring LE devices, that ensured loss of control, not loss or lack of lift per se.

Perhaps a graph showing the effect of flaps and that of LE devices will make it clearer.. a picture is worth a thousand words.

..but its late, my eyes hurt and its time for beddy byes. Ask and it shall be given (later)....

[Will Fraser]

My point being that altering a wing's camber on T/O will cause havoc if not done with care. I agree with all your points. Slats do ennable Lift, is what I'm sayin. I see it as raising the wing, but effectively lowering the leading edge, creating a stubby high camber high lift wing at a speed the a/c could not otherwise fly at. Are you saying the slats ennable an effective lowering of Incidence, cause that's what I'm saying.

[HarryMann]

Yes, slats do appear (visibly) to increase wing camber as flaps do.

However, their predominant effect is (and always has been) to re-energise top-surface flow at high incidences due to the slot effect (when otherwise it would be breaking down)

[noblues]

It goes back to basics in the heat of the moment, ie.

Stick Shaker = Stall recovery = full power, lower attitude

Its not a scenario that I have ever had thrown at me in a sim at that phase of flight ....

I would imagine initial reaction of crew is that they have used the wrong figures as a mass of red appears on the speed strip.

[Will Fraser]

Out on a limb, no problem. The LE slats accomplish an extension and droop of the leading edge of the a/c wing. The extension widens the chord, the droop increases the camber. This is obvious, what seems to be at issue is the function of the "holes in the area left open by the slats". Wiki tells us the holes are the critical gain of the mechanism. I disagree. An aside: Wiki is bollocks in many ways, sit on it with caution.

Further, I'll introduce the concept of the "Blown" wing, to illustrate why the holes are not the deal, this time it is the cheese. See NASA's QRSA, an interesting experiment in short field performance. After reading up on the QRSA, think of the slats leaking underside airflow upward and see if you think the concept is what applies to slats. As air flows into the leading edge of the slatted wing, more will flow over the top than the unslatted config. this is a way of holding back the Stall, surely, but Stall isn't the consideration, foremost, lift is. A wider chord and increased camber airfoil produces more lift at any speed than the standard wing. Once slow speed lift augmentation is accomplished, they are retracted. The ribs that extend the device do just that, they are not there to allow airflow to change its mind and swap sides after passing the leading edge. At 100 knots, how much airflow will change direction by nearly 90 degrees to passively "Blow" (supercharge) the top surface?

Wiki indeed.

Will

[fox niner]

I suppose they were also having an advantage from still being in the ground effect. at 32.8 feet.:eek:

[Captain Airclues]

The 747-400 does not have Slats (whatever Wiki says). It has a mixture of Kreugar Flaps (inboard) and Variable Camber Leading Edge Flaps.

Dave

[Joetom]

All very hard to understand.

I guess Boeing will review the DFDR and various reports they have, may be they will remove the L/E/H/L/D from the 747/44 to save weight, but a I have feeling may be they won't.

To knock the same old nail, well done to all involved, lets hope we don't have a repete act with the 747/44 L/E.

[Pinkman]

I've read this thread again from start to finish and I still don't understand exactly what the crew did and why. Given that the amber rev unlocked lights were on for 2 & 3, and given that that the stick shaker deployed before they realized that the L/E devices were retracting, did the crew advance thrust on all 4 engines (the right course of action in this case) or just 1 & 4 (which you might say was a more intuitive action if the inboard reversers were in fact starting to unlock).

Or did they just say "well, if both inboard reversers are unlocking, the aircraft isnt going anywhere anyway so we've nothing to lose by assuming it's two false indications and taking it to the max on all four".

In fact it's more than that, because without knowledge of the L/E slat retraction surely the intuitive assumption would be that the activation of the stick shaker was due to a degradation of performance caused by the inboard reversers starting to unlock?

The thing that I cant understand is that they appear, on the basis of the admittedly shaky info on this thread, to have done the right thing based on illogic...

Much respect, whatever the reason.

Pinkman

[TyroPicard]

The simplest technique is always to put all thrust levers to Full thrust - when things have calmed down you can decide where the problem lies. In the heat of the moment being selective may equal being wrong.

[the heavy heavy]

Pinkman,

in summary:

the handling pilot flew the jet by feel into a dark hole at night with the jet at aroun 10'-20´ for what must have seemed like forever. 10deg pitch its hits the ground, 11.5deg it stalls. thank god he had the talent and experience to operate so far beyond the scope of our scenario driven training.

the skipper faced with no way of knowing what was happening on the wing made 2 decisions which it would appear, in tandem with the outstanding efforts of his co, got everything moving back into the right way.

Im not spock but I think it´s harsh to imply it was illogic thinking that saved the day here. what saved the day was a great deal of talent backed by an ability to make decisions under huge levels of stresss and uncertainty.

Im biased. I know both individuals and will consider it my privilage to buy them both a bottle of whatever they like when next in the bar. they saved a jet full of lives and possibly, but less importantly, my company and therfore my job.

Bravo gentleman.

[jimpy1979uk]

In answer to Dave's reply to reprogramming the FCUs to not have the autoflap function at flaps 25 and 30.

I would guess it would be possible to reprogram the FCUs so they could work in the sense you describe but without knowing the internal workings of the FCU I wouldn't like to speculate on what could be possible.

I have looked at the wiring diagrams for the T/R and Flap Systems and it is fairly simple in that when either T/R1+4 or 2+3 are detected unstowed(not deployed) and aircraft on the ground the Group A flaps retract. The input to the FCU from the T/R position system is a ground that is switched by a relay so I would imagine that Boeing would look at interlock circuit involving relays with some input from another source such as the throttle lever as previously suggested.

Hope this is of interest.

[Skyboeingengineer]

Slat function carried out on ground which involved T/R function not enough air because of sea level of jnb.T/r did not go back all the way but looked alright on ground.This did not show up until T/o roll.Expect to see changes to MM after Slat and T/R functions by Boeing.

[Pinkman]

You're reading harshness where none was intended. What I was trying to understand is what led them to make the choices that they did when so many scenarios presented themselves in a few seconds. Thats all. If you PM me your address I will happily send you the cost of a second round in the pub for your colleagues. When I lived in RSA I flew that service often, either directly or via a Comair feeder when the CPT-LHR service was full. As I said in my post...much respect.

[Edit] Now we begin to get answers: SkyBoeingEngineer indicates that there was mtce carried out. I assume that would have been briefed in the handover. So that more or less answers my question about why they did what they did. The Rev Unlocked lights didn't 'just come on'. They came on during the t/o roll following prior operation of the T/R on the ground by mtce. The crew made the choices they did, not illogically, but with the knowledge that it was likely to be spurious and that it would have caused the inboard L/E devices to retract. Thats all I wanted to know.

[Bitburger]

I did not take the time to read trough the whole story.

I seems to me that the air/ground logic must be in ground mode for the LE Flaps to retract.

How can this happen in the Air?

[Pinkman]

Bitburger

It didn't happen in the air. It happened on the ground after V1 but before Vr. It pays to go trough the whole story.

[Juliet Sierra Papa]

"The ribs that extend the device do just that, they are not there to allow airflow to change its mind and swap sides after passing the leading edge. At 100 knots, how much airflow will change direction by nearly 90 degrees to passively "Blow" (supercharge) the top surface?

Wiki indeed."

Will Fraser, surely that is exactly why it happens....the higher pressure underneath creates the lift and if there is a hole anywhere then the higher pressure will bleed to the lower, regardless of speed of Aircraft or airflow.

JSP

[HarryMann]

Will, I use Wiki a lot, but not for basic aerodynamics. 5 years studying for an Aero Eng Degree and practicing a wee bit afterwards means I don't need to...

The predominant effect of le devices is to extend the lift curve slope,
The predominant effect of flaps is to give a Delta Cl increment (with varying degrees of Delea Cd, becoming very significant at full flap positions)

I was indeed talking slotted le devices, but even if not slotted on the 747, the le camber has a similar effect, the predominant one (Wiki has it right) to extend lift curve slope (to higher alphas), since without the le camber, flow breakdown will occur earlier - but yes, an extension and camber will give a delta Cl increment as well.
So in actual fact for the 747 we're both right :)

As pointed out above, the pilot flying was doing a great job right on the edge of a cliff, between the devil and the dep blue sea, having a very narrow margin of operational alpha until he could dump some drag and pickup a few knots here and a few there...

Another Sully, making simple, basic, and most importantly quick decisions! He won't get to retire and write a book though... :rolleyes:

[NSEU]

"he 747-400 does not have Slats (whatever Wiki says). It has a mixture of Kreugar Flaps (inboard) and Variable Camber Leading Edge Flaps."

The variable camber flaps on the 747-400 do have an air gap between the flap and the wing, so probably exhibit slat-like behaviour.

[SMOC]

Rollers on the 400 have a poorly designed proximity switch which has a long history, the fix by some airlines has been to check the rigging more frequently to prevent unwanted reverser messages, air load and/or thrust loads can cause a slight shift of the reverser as you could expect as components wear which sets off the proximity switch. Locking out the reverser doesn't fix the problem always either as the wear and or rigging won't be fixed by a locked out reverser, so you lock it because of the faulty message taxi out set thrust get the same message. Delay flight to re rig reverser? You can't change the reverser either as it requires the entire engine to be changed.

Experienced RR guys have probably seen all this before so know or try to do what they can to prevent unwanted reverser messages.

Was any work carried out on any of the reversers while in JNB?

The 'air gap' will also be a feature of the new 747-8 I/B Kreuger flap it's being redesigned for this purpose.

[BOAC]

A tribute to basic flying skills indeed and another weight to chuck into the on-going debate about the on-going erosion of those skills.

For my benefit (assuming I have this right), can anyone give me an idea of the time scale for all this? I. E. typical V1/Vr in Jo, how long retraction would take on the faulty signal and how long again to re-extend on the a/g switching? Do the L/Es have to complete retraction before they will re-extend or can they be instantly 'reversed'?

[SMOC]

7 seconds rings a bell for some reason and they would not need to complete a full cycle, should just stop and then change direction.

[BOAC]

NB NO 747 experience...

Whilst I resisted calls for 'Boeings head' on the Schipol Radalt accident, and given that as usual we are all working here on 'hearsay', I would question why B did not think about this 'failure' and its consequences above V1. Assuming it happened above V1 as stated, it left the crew with no real options but to continue with a crash extremely likely. The ensuing rotation must have been eye-watering! The call for inhibition of the LED retraction with more than xx power set is very strong.

If this failure should happen below V1 but at high speed............ I guess the T/off emergency briefs will be changing until mod action is in place.

[TopBunk]

I guess the T/off emergency briefs will be changing until mod action is in place.

A think that you will find most 747-400 drivers will now call stop for a thrust reverser amber, with or without any other cue (swing etc).

Ex JNB at about 350 tonnes TOW, the V2 will be about 174kts with V1 about 155 and Vr high 160's at a guess, take off roll about 65 seconds and 4000 metres.

[TyroPicard]

The crew made the choices they did, not illogically, but with the knowledge that it was likely to be spurious

If I had an unlocked warning on the T/R(s) that maintenance had been working on, I would not assume it was spurious!!!

[TopBunk]

tyro

I believe that the inbound crew had reported a failure of the autospeedbrake on landing. The outbound crew would probably have been faced with an engineering item saying that some 'tests as per Maintenance Manual x.y.z carried out, and system satisfactory.'

They would not know what specifically had been carried / have reason to suspect that the reversers had even been part of that procedure and would have taken it as read that the engineers had done everything as per the book.

[TyroPicard]

You may well be right, TopBunk, but I was responding to a statement by Pinkman about the thought processes of a crew who had been fully briefed about maintenence actions, which then transpired to have not been correctly done...

I believe that the inbound crew had reported a failure of the autospeedbrake on landingRectification of which presumably would not involve the LED and T/R....

[gas path]

TopBunk.......... correct!
Rectification of which presumably would not involve the LED and T/R.... TyroPicard............ also correct!

[Carnage Matey!]

Pinkman - there'd have been no handover after the maintenance. The aircraft lands in the morning and leaves in the evening. Probably wasn't even the same engineer on duty when the outbound crew accepted the aircraft.

[Desk Jockey]

I think they might have scribbled a little note in the log.

[Desk Jockey]

Didn't work the 747, does reverse thrust pop the speedbrake lever up?

[Pinkman]

there'd have been no handover after the maintenance. The aircraft lands in the morning and leaves in the evening. Probably wasn't even the same engineer on duty when the outbound crew accepted the aircraft.

Please tell me that you're pulling my leg. Surely when a new crew accepts an aircraft they get briefed on any aircraft performance issues on the inbound leg, any maintenance actions, MEL items etc? It shouldn't matter whether the aircraft has been on the ground two hours or twenty hours or how many shift changes there have been in between.

I cannot believe the crew did not know about any maintenance, whether or not it involved the reversers and whether or not the reversers were actually deployed on the ground per the earlier post. This goes back to my earlier question about whether all or just 1 & 4 engines were firewalled. Why would you firewall the other two engines if you seriously believed the reversers actually had deployed?

[arem]

<A think that you will find most 747-400 drivers will now call stop for a thrust reverser amber, with or without any other cue (swing etc).>

Not after V1 I hope!!


and yes the crew would have known of any engineering input as soon as they reached the aircraft and examined the tech log.

[Carnage Matey!]

The tech log will tell you what the speedbrake defect was on landing and whether or not the engineer cleared that defect. If they want to know the procedure used to fix the defect they can look in the MEL. If Pinkman thinks that there'll be an engineer waiting at the aircraft waiting to personally brief the flight crew on what was done in detail then he'll be disappointed.

[Joetom]

The maint manual will tell how to invest/test/fix. (FIM)
.
The MEL may tell you a lock out proc or similar.
.
Trying to read between the lines here, systems may have been tested using APU or ground cart air, duct press may have been unstable due demand of Rev's and demand hyd pumps(ADP's) due spoiler ops.

The above may lead to Rev's being stowed and locked, but just not at the max closed/near position(prox) a prev post by SMOC is about right, Hi power and a few bumps on the T/O could be just enough for prox to be far.

Remember, in normal operations, 4 engines running = good duct px for Revs and demand pumps(ADP's), plus 4 EDP's giving loads of hyds for spoilers.
.
The following link is a good slide show..
.
Fc744 Flightcontrol (http://www.slideshare.net/theoryce/fc744-flightcontrol)
.

[Pinkman]

If Pinkman thinks that there'll be an engineer waiting at the aircraft waiting to personally brief the flight crew on what was done in detail then he'll be disappointed.

I guess I'm disappointed. In my industry (fuel refinining) where equipment fails at any time of the day/night, is fixed, things catch fire and go bang causing the same kind of loss of life as your average aircraft disaster we personally brief EVERY shift, EVERY handover, have tech logs, defect logs, etc. Its very formal.

[vs69]

Desk Jockey: Yes engines 2 and 4 in rev will auto deploy speedbrakes - Other conditions also need to be met i.e a/c in ground mode. (To overcome the lever lock solenoid)

[NSEU]

To overcome the lever lock solenoid

Isn't that something to do with the landing gear lever? :}

[vs69]

Not according to the schematic!

[NSEU]

Yes, there is also a "lever lock solenoid" on the speedbrake schematic.

However, this relates to the Flight Detent. It has nothing to do with Autospeedbrake ops ;)

CHeerS
NSEU

[Nevermind]

It always amuses me to see everyone picking over the bones of these incidents in great detail, being wise after the event.
I thought that's what official investigations are for?


Having heard what actually happened from those VERY close to the event, I assure you it relies on pure instinct and all those hours of flying you've managed to accumulate over the years. So when the details are finally published, it would be nice to see all self appointed experts return to this thread and give the crew all the credit they will undoubtedly be getting.

And perhaps put themselves in the position of those who found themselves in a situation way outside anything ever they've ever experienced or been trained for.

[Pinkman]

Nevermind

If thats the way you view PPrune, then the forum isn't for you. The forum is for people - nominally pilots - that view what they do as more than a job, have impatient, inquiring, minds, and are passionate about continually learning from mistakes, incidents, and near misses to improve their own performance. It includes not just pilots but some of the finest technical experts in other aviation related areas including ATC, engineering and maintenance, airframes, aerodynamics, runways, fuels, aviation medicine, aviation law, and much more.

The accessibility of the forum means that you get a proportion of posts from idiots, poseurs, and tosseurs, but the moderators weed much of it out. I don't see anyone on this thread being wise after the event. I don't see anyone on this thread criticising the crew or setting themselves up as self appointed experts.

What I DO see is lavish praise and huge amounts of respect for that crew as people on this forum try to understand what happened and why.

Read post 97 on this thread from 4PWs and tell me how you get to where you are from there...

[Nevermind]

Pinkman

I think the key word in your posting was "impatient."

And I think I'll be the judge of whether I think it's a forum I frequent.
You'll find many people do, without needing to comment.
Sorting out the wheat from the chaff as we go.
I just get tired of people poring over detail, try to be wise after an event, especially when the event in question didn't have the luxury of time.

I appreciate the time you took to reply but all I really took out of it was you telling me to go elsewhere if I disagreed with the contents of people's postings.

[Will Fraser]

There will always be what there is here. Much to criticise in the writing, the level of expertise and experience, etc. Personally I am mildly annoyed by those whose main contribution is to "wait for the report". Rather obvious that those who post here aren't waiting for the "Report". A report that is generally years away, when there is so much to discuss, as professionals, while the investigate body is getting ALL their Ducks in a row.

I appreciate everyone who adds to the commentary, ruffled feathers and all. I take away much in new perspective, patience and a sense that many fellow pilots are engaged in a worthwhile endeavor. Flying commercially requires nothing if not a thick skin.

Will

[Nevermind]

Will

Are you saying that if there was something fundamental about the situation that we needed to know, manufacturers, airlines or authorities wouldn't be letting us know about it?

Mildly annoyed?

Steady !!!!!!!!

[Desk Jockey]

What they said!

I come on here to be interested, learn and educate.

[Will Fraser]

Postulates of Fuel icing in the Trent were broached well before NTSB, Boeing, and FAA made the mechanism known. Not that that saved the day by any means, but posters here were questioning items like "in spec" fuel well after AAIB held that fuel icing was not the problem (after all, the fuel was in spec!). Yes, I would say that the authority drags its feet at times. Who's to say they weren't reading PPRuNe? The upshot of that massive thread is that all who posted may well have come away with a good deal more knowledge about, and caution for, the possibilities of heretofore unanticipated faults. Professional communication to me, is a good thing.

[Nevermind]

"Who's to say they weren't reading PPRuNe?"

Can I be the first to say it?

[Pinkman]

Will is right. Another good example is the Bristol (BRS) runway resurfacing incidents where at least three "serious incidents" (AAIB) occurred in a short space of time in late 2007. The debate happened in real time, and without question the PPrune commentary, which spilled over into the media, influenced operators decisions to suspend ops (initially EZY then others), prompted a visit by the regulator, and forced the closure of the airport, potentially preventing more incidents. Revisions to the CAP, that were being considered at the time, were reviewed in the light of that incident. The airport chief executive left shortly afterwards. In that particular case I KNOW that the regulators were reading PPrune.

You have to ask yourself what would have happened if everyone had sat back and "waited for the official report". Thankfully, we'll never know.

[Joetom]

Just a bit of back ground to Will Fraser's last post.
.
http://www.pprune.org/3860762-post771.html
.
We can treat Pprune like a Lighthouse, some people may not like the way they look, but Lighthouse's have saved many a man !!! (boats and planes)

[Will Fraser]

Pinkman, Joetom. Two of those writing in the 038 thread I've read with interest. Also many others, I've read and reread that entire thread many times, and enjoyed it each time for the insights its provided. Machaca, Airfoilmod, FE Hoppy, etc.

I also would note that with each new thread I see new people posting, most certainly up to the challenge. It takes nerve to lay out one's writing, but as I've said, commercial aviation requires nothing if not nerve, (also cheek, if I have UK usage correct).

Knowing the story involves collecting information. So much presents itself here, the benefits must be noticed and affirmed. It is not like pilots and aviation pros to be shrinking violets, some don't understand this. I'm trying to think of anyone I've met who would hush someone in earnest discussion re: incident/accident by saying "We mustn't discuss; the report will be out in time."

Will

[Union Jack]

You have to ask yourself what would have happened if everyone had sat back and "waited for the official report". Thankfully, we'll never know.

As a backseater in the first flight into Bristol after the necessary work was completed in Jan 2007, a Continental B757-200 ex Newark, I can only add "Hear! Hear!"

Jack

[Swedish Steve]

I believe that the inbound crew had reported a failure of the autospeedbrake on landing. The outbound crew would probably have been faced with an engineering item saying that some 'tests as per Maintenance Manual x.y.z carried out, and system satisfactory.'

They would not know what specifically had been carried / have reason to suspect that the reversers had even been part of that procedure and would have taken it as read that the engineers had done everything as per the b

The incoming defect was Autospeedbrakes inop.
The answer was tested as per AMM 27-62-00 and all chks sat.
There was no way the crew would have known that T/Rev was involved unless they were very clued up.
Part of the autospeedbrake test is lifting the T/Rev levers to check that the spoilers respond correctly. The reversers are not supposed to move, as you do this test with pneumatics off. But the RB211 has a pneumatic thrust reverser. It can happen that, even with the air off and APU shut down, that moving the thrust reverser lever on the ground can cause the reverser to move, using air trapped in the ducts. It has happened to me on a B767 (with the same engine). It really surprised me at the time. The APU was shut down, but the reverser moved nearly full travel on trapped pressure when I wasn't expecting it to.
The AMM does point this out, but at the end of the test there is no specific reference to ensure the reversers are stowed and locked.

[Joetom]

Duct px may read zero on EICAS.

Px inside air pipes inside engine may be more and volume is enough to operate a Rev through a full cycle (stowed/full deployed/stowed) in some conditions.

Sounds like a change to the AMM is not far away.

Best way to test Rev is when engine is operating, using APU or cart air can be ok, but if normal operation is with engine running, we can only expect different results in different conditions/supplies of air, it's a lot less hassle to use APU or cart air.

May be reduce the limits/values of the Rev pos tx (TRCP), however think they were increased to keep the FADEC happy in flight !!!

[TyroPicard]

The AMM does point this out, but at the end of the test there is no specific reference to ensure the reversers are stowed and locked.

Does the AMM tell you to make sure there is no trapped air before reverse selection, e.g. by opening packs valves? Or does it just point out that it can happen?

[Pinkman]

So the solution is.... what?
- Specify higher performance air carts at high altitute airports?
- Mandate that the crew of the next leg cycle the T/Rs after startup of APU and/or engines prior to departure whenever the T/Rs have been deployed on the ground? (would need to be in the log!!)
- Redesign the limit switches?
- Improve the L/E device stowing logic to prevent stowage when going from ground -->air mode as opposed to air -->ground mode.
- All of the above?

[Stanley Eevil]

Premature slat/leading edge flap retraction occurring without a conscious, deliberate pilot-made lever selection equals basic design flaw in my opinion. And why do we need spoilers that deploy `automatically`? Don`t we trust pilots to make their own manual selections anymore?
Thank goodness I fly a first generation (British) 4-jet airliner.

[Swedish Steve]

Does the AMM tell you to make sure there is no trapped air before reverse selection, e.g. by opening packs valves? Or does it just point out that it can happen?

The trapped air is in the engine and pylon, between the isolation valve in the wing, and the thrust reverse selector valve. I suppose you could select APU off, then select engine start to dump it through the starter, but I have never seen this promulgated in a manual. ( It would not work with the APU running as engine start opens the wing isolation valve.)

[paracetamoxy]

Just innocent bystander SLF, but something occurs to me.. What was the ambient Temp on that day? Early winter in JNB at the mo, so temp in the evening must have been around 21C at the most. What would the outcome have been if this had occurred in the height of summer when ambient temp and density altitude would have been much higher? December evening temps can reach 27-28C easily. Would this have changed outcome, or would the aircraft have been more lightly loaded negating the difference? Anyhoo, good work by the PIC saved the day..... Creeps back under rock......

[happybiker]

The FAA has issued an AD to correct the unsafe condition. This AD results from a report of automatic retraction of the leading edge flaps during takeoff due to indications transmitted to the flap control unit (FCU) from the thrust reverser control system. The AD requires a modification to the wiring of the thrust reverser control system to the FCU within 60 days from 6th July.

FR Doc E9-15255 (http://edocket.access.gpo.gov/2009/E9-15255.htm)

[J-Class]

As humble SLF, I just find it so extraordinary that a twenty-year old aircraft model, with hundreds of examples in service and a long statistical history of perhaps millions of takeoffs, can be discovered at this late stage of its life to have a very serious logic bomb in its control software. Amazing, simply amazing...

[clivewatson]

Rainboe has been very quiet of late.

Surely he would have figured it all out on Page 2, suggested what additional training the crew may be in need of, and advised Boeing on possible system retrofits.

[Sir George Cayley]

Just some respect for Will Fraser.:)

Gettin' "heretofore" into a thread scores double:ok:

Now, can you work 'antidisestablisment' in there somewhere?

ps I'm late on here but I understand BA have sussed out the problem and amended downline maint procs accordingly. Won't happen again. Nothing to see here - move along now.

Sir George Cayley

[chris weston]

Sir George,

You could be right, any tendency for antidisestablishmentarianism to spread its wings within this thread should be encouraged at all costs.

Sending Danny to Ireland or Wales seems the wrong way for PPruNe to go.

Oh and its a long time since I used that word in anger .............

CW

[NSEU]

As humble SLF, I just find it so extraordinary that a twenty-year old aircraft model, with hundreds of examples in service and a long statistical history of perhaps millions of takeoffs, can be discovered at this late stage of its life to have a very serious logic bomb in its control software. Amazing, simply amazing...

This logic bomb you speak of takes two identical engine failures to make it happen (and on symmetrical engines).

The trigger for this fault is an improper alignment between the reverser cowl and a cowl position sensor mounted, I recall, on the engine support strut (on two engines).

Reverser cowl indication problems haven't been super rare, but sensor adjustment procedures have been changed in the past to make the indications less likely to occur. Any problem of this nature should be fixed within a maximum of 10 days (further narrowing the possibility that two engines should suffer the same fault on the same aircraft). Sometimes cowl adjustments have to be made, but groundtime and the skill/knowledge to do this job are not always present.

Cheers
NSEU

[einhverfr]

As humble SLF, I just find it so extraordinary that a twenty-year old aircraft model, with hundreds of examples in service and a long statistical history of perhaps millions of takeoffs, can be discovered at this late stage of its life to have a very serious logic bomb in its control software. Amazing, simply amazing...

To give you an idea of how rare this is, the B747-400 had at least 5 million take-offs by 2008. And this is not including earlier versions of the B747. So the failure condition has to be extremely rare for this sort of thing to happen.

[J-Class]

Yes, it's the rarity of the event which makes it interesting - a 'black swan' piece of computer code which had lain dormant for five million takeoffs, if not more.

The sad thing for gamblers amongst the 747 pilot community is that at a one in 5 million risk, you were still nearly three times more likely to experience this set of circumstances than to win the national lottery jackpot (1 in 14m odds)!

[Joetom]

When you talk of odds, you need to think 744/RR, this one has a long history of Rev probs, both Ind and operation, the 744/GE/PW have few problems.
.
Cheap lesson, well done to the 056 crew.

[Pinkman]

...and of course of all places for it to happen, it had to happen in JNB, one of the highest altitude airfields on the BA route map.. talk about the potential for holes in the cheese....

[Torquelink]

When you talk of odds, you need to think 744/RR, this one has a long history of Rev probs, both Ind and operation, the 744/GE/PW have few problems.

Extract from Boeing SRB Bulletin issued today:

The GE and PW configurations differ from the R-R in that they use the thrust reverser auto restow sensor signal rather than the thrust reverser unstow sensor to automatically retract the LE flaps. Thus, for GE and PW configurations, the Group A LE Flaps will automatically retract if the aircraft is on the ground and either reverse thrust is selected via the reverse thrust levers of both outboard or both inboard engines or an auto-restow signal is received from both outboard or both inboard engines.

While the rate of auto-restow events on the GE and PW engines is lower than the rate of unstow indications on the R-R engines, and no dual auto-restow events are known to have occurred, the Boeing SRB determined that the result of a dual symmetric auto-restow event is a safety issue and a safety SRP was initiated for both engine types. The Ref /C/ and /D/ SRPs were initiated for the PW and GE engines respectively. We are planning to hold technical teleconferences within the next two weeks to further discuss the Boeing SRB decision and answer any operator questions. Additional information on these telecons will be provided via follow-on communication. Further updates will also be provided in the Ref /B/ Fleet Team Digest article.

[ian16th]

Until recently, SAA were flying B747's with all three engine types, out of JNB :bored:

[SW3Flyer]

Does anybody know any further information into the investigation?

[Joetom]

Think I heard the FCUs will be looking for another input before they retract the L/E flaps, may be a 20% or 30% TLA/TRA or wattever it's called, thought it was due before year end(2009), may be it's not so simple, 056 crew did a good job by all accounts.

[SouthpawSLF]

All 747's are not created equal. With the exception of the SP (not sure about that one), all will retract the 'Group A' LE Flaps upon receiving a 'ground' signal from the A/G logic AND receive signal from the thrust lever that reverse thrust has been selected. Retraction of the Group A devices based on either #1 & #3 OR #2 and #4 T/R position was added as basic to the 747-400's (certified in 1989) as well to provide additional redundancy to the system design. The concept of LE flap retraction mitigates fatigue damage to the flap panels from the reverse thrust. The Group B panels do not retract; these are outboard of engines #1 and #4.

The Boeing S/B changes the signal wiring to the Flap Control Unit such that 747-400's will retract the LE devices only upon selection of reverse thrust - making them the same as the older 747's There is an additional S/B for the 747-400's which changes the position of the signal switch in the thrust handle that triggers reverse thrust selection until AFTER the interlock position of the reverse thrust handle. This bulletin is independent of the FCU wiring change and was the result of LE retraction during take off when the reverse handles contacted a book on the isle stand just enough to signal reverse thrust during selection of TO thurst.

...and I will toss my Kudos to the 056 crew as well - great job....

[Spaced Out]

SouthpawSLF said it, kudo's to the crew of 056.

[Doors to Automatic]

The sad thing for gamblers amongst the 747 pilot community is that at a one in 5 million risk, you were still nearly three times more likely to experience this set of circumstances than to win the national lottery jackpot (1 in 14m odds)!

That is off course assuming that the average person experiences the same number of 747 take-offs as they buy lottery lines.

If the average person buys 52 lines per year then in their adult life time of say 60 years their odds of winning the lottery are 1 in 4487

If they fly an average of 2 sectors per year in a 747 their odds of experiencing this failure are 1 in 41666

Therefore you are actually almost 10 times more likely to win the lottery.

Don't you just love statistics!

[overstress]

Gamblers amongst the pilot community, not SLF

[Flying Lawyer]

http://www.gapan.org/template/theme/gapan/img/im-guild-crest.gif



http://img.photobucket.com/albums/v140/Rotorheads/Aviation/GAPANbanner_600.jpg


The Master's Medal

Awarded to any person in aviation, at any time, for an act or achievement in aviation considered worthy of the Medal, as soon as the facts of the event are clear.


CAPTAIN MICHAEL FAIRHURST & SENIOR FIRST OFFICER JAMES BROWN


Citation: On 11 May 2009, during a normal Boeing 747-400 departure from Johannesburg, with the First Officer as the handling pilot, the Number 3 engine Thrust Reverser 'In Transit' indication appeared at 125 knots followed by the Number 2 engine Thrust Reverser 'In Transit' indication at 160 knots. There was no deployment of thrust reverse and the 'In Transit' indication is not easily visible and was not seen by the crew who were concentrating on the take-off.

At this point the Group A sections of the leading edge flaps, which are a significant proportion of the leading edge high lift devices, retracted as they are designed to do when reverse thrust is selected on landing. Unaware of the changed leading edge configuration, the First Officer rotated the aircraft and the crew were immediately confronted with significant airframe buffet and the stick shaker activating. The crew had no idea why the aircraft had apparently entered a stall or pre-stall regime. As they were dealing with the emergency the Group A section of leading edge flaps started to re-deploy shortly after the aircraft became airborne.

The First Officer flew an attitude that prevented the aircraft stalling but also prevented contact with the ground despite being unable to read the instruments clearly due to the buffet. The Captain calmly supported the First officer by passing on critical information such as speed and aircraft height above the ground. He also raised the landing gear. The handling difficulties were initially made worse by the increase in drag created by the opening of the landing gear doors during the retraction process and the initial movements of the leading edge flaps as they started to redeploy. After the leading edge flaps had re-extended (taking 23 seconds) the aircraft performance returned to normal and the handling aspects of the event were over.

The crew still had to deal with an unknown set of circumstances. They decided to return to Johannesburg and planned for two, three and four engine approaches given the unknown nature of the fault. They also ensured that customers and the cabin crew were kept informed and remained calm and relaxed throughout.

Captain Michael Fairhurst and Senior First Officer James Brown displayed exemplary skill and professionalism while dealing with this emergency that occurred at a critical phase of flight. Both members of the flight crew played a significant role in recovering the aircraft safely from the very hazardous situation they were confronted with. Their actions undoubtedly saved the aircraft, and countless possible injuries or fatalities to those onboard, and they are accordingly awarded the Master’s Medal.



The Medals were awarded to the pilots some time ago and formally presented at the Guild's annual 'Trophies and Awards Banquet' at the London Guildhall at the end of last month.


GAPAN - The Guild of Air Pilots & Air Navigators (http://www.gapan.org)
Patron: HRH The Prince Philip, Duke of Edinburgh
Grand Master: HRH The Prince Andrew, Duke of York



.

[TopBunk]

Very worthy recipients of the award - well done chaps, very proud of you:D:D:D

[fast cruiser]

cracking effort chaps... well deserved :D:D

[Teddy Robinson]

very well deserved... truly a professional performance.

[Crosswind Limits]

This has got to be the same James Brown who does aeros at While Waltham! I can't believe BA has 2 SFOs on the 744 with the name James Brown!! :p If so Well done James and also your colleague Captain Micheal! Excellent airmanship - would have expected nothing else from you!:D

[HEATHROW DIRECTOR]

Excellent and well deserved. It's knowing how able the crews are which gave me supreme confidence whenever I boarded a BA aircraft.

[KyleRB]

Would agree that British Airways flight crew and training are amongst the best in the world. Have come across quite a few BA pilots and without exception they all give me great confidence in our national flag carrier! Well done guys!

[eastern wiseguy]

Was that the Mike Fairhurst who used to be an air traffic assistant at Scottish years ago? Well done guys . :D

[Aerostar6]

....the very same Mr Fairhurst, ex-ATCA..............

[flyawaybird]

Exemplary performance! Speedbird, Keep it up!:ok::D

[flyawaybird]

Just a minor correction here. The Airport in 70s, was known as "Hellenikon Airport", in Athens.:)

[ratarsedagain]

This has got to be the same James Brown who does aeros at While Waltham!

One and the same!

Well done guys, well deserved:ok: