AAIB initial report out on BA B777 crash at LHR
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I would commend Dinger X and Hand Solo for their excellent analysis of the real driving force here - PR. We are faced with a press who know little about flying generally, and absolutely nothing about the B777 specifically. Couple this to an insatiable public appetite for tit-bits and news editorial pressure for programs to be filled and you have a bottomless pit of disinformation. The inevitable result is endless speculation and intrusion, coupled to the creation of heroes today who may become villains tomorrow. The AAIB initial report is the only true knowledge that anyone on this forum really has, myself included. I have no doubt that the likely causes of this accident have already been narrowed down to a very small range of possibilities indeed. Quite rightly the few people who really do know what is going on are acting as the cautious professionals they are, and have chosen to remain silent until all doubt is removed.
For what it is worth, my take on the BA handling of this accident is that they have been absolutely faultless. They have provided just enough entertainment to throw the numpties off the scent for a few days, whilst ensuring their brand exudes professionalism and skill in the face of an impossible emergency. From clapping employees to suave looking crew on display to the world who say everything but tell nothing, they have done it exactly right. I do not blame them one bit, as they have acted wisely to protect their company from a loss of consumer confidence and all that would mean for BA. They have simply avoided turning a 'drama into a crisis'
Whilst we all await any real information, I am reminded of the immortal words of the former US Defense Secretary, Donald Rumsfeld -
"Reports that say that something hasn't happened are always interesting to me, because as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns -- the ones we don't know we don't know."
Isn't that the truth?
For what it is worth, my take on the BA handling of this accident is that they have been absolutely faultless. They have provided just enough entertainment to throw the numpties off the scent for a few days, whilst ensuring their brand exudes professionalism and skill in the face of an impossible emergency. From clapping employees to suave looking crew on display to the world who say everything but tell nothing, they have done it exactly right. I do not blame them one bit, as they have acted wisely to protect their company from a loss of consumer confidence and all that would mean for BA. They have simply avoided turning a 'drama into a crisis'
Whilst we all await any real information, I am reminded of the immortal words of the former US Defense Secretary, Donald Rumsfeld -
"Reports that say that something hasn't happened are always interesting to me, because as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns -- the ones we don't know we don't know."
Isn't that the truth?
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In attempt to keep this thread how it started (RE:cause); two links:
http://www.pprune.org/forums/showpos...&postcount=137
(A good FAA B777 Remit post)
...and my post about it here:
http://www.pprune.org/forums/showpos...&postcount=160
http://www.pprune.org/forums/showpos...&postcount=137
(A good FAA B777 Remit post)
...and my post about it here:
http://www.pprune.org/forums/showpos...&postcount=160
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The FOUR "on the money" Posts here
Having taken the time and trouble to read all the BA 777 crash threads and analyze them (all) for their intrinsic worth, I've concluded the following about (by far) the most meritorious line of probable cause:
He was picking up the theme originally started by Belgique in the previous thread at post 939
and commented upon by UNCTUOUS in the previous thread at post 954 - but NOT later referred to by Riverman in this thread.
then interpreted further (in this thread) in that post (#137 of this thread) by Riverman (referred to by Huggychair)
Among all the 1000's of rabbiting Pprune posts about the accident (and a very few that have commented upon these four in particular) only those four posts seem to be quite "on the money" and inspirational as to a real possible and plausible cause.
.
Hats off to those gents (i.e. they like more than the sound of their own rants)
huggychair said (in post 160 of this thread)
I Think that Riverman (post #137) may be on the money here, icing may not have been an immediate issue here but a contributory one to the sensor points/connections (moisture).
The fact that it was picked up by the FAA on the G.E. powerplant rather than a Rolls-Royce one (on the same aircraft design) should make little difference to the underlying cause. Just because the FAA didn't put out an APB on the Trent engine doesn't mean they're infallible to the same control/FADEC issues!... it just meant they hadn't dealt with them at that time....etc etc
I Think that Riverman (post #137) may be on the money here, icing may not have been an immediate issue here but a contributory one to the sensor points/connections (moisture).
The fact that it was picked up by the FAA on the G.E. powerplant rather than a Rolls-Royce one (on the same aircraft design) should make little difference to the underlying cause. Just because the FAA didn't put out an APB on the Trent engine doesn't mean they're infallible to the same control/FADEC issues!... it just meant they hadn't dealt with them at that time....etc etc
He was picking up the theme originally started by Belgique in the previous thread at post 939
and commented upon by UNCTUOUS in the previous thread at post 954 - but NOT later referred to by Riverman in this thread.
then interpreted further (in this thread) in that post (#137 of this thread) by Riverman (referred to by Huggychair)
Among all the 1000's of rabbiting Pprune posts about the accident (and a very few that have commented upon these four in particular) only those four posts seem to be quite "on the money" and inspirational as to a real possible and plausible cause.
.
Hats off to those gents (i.e. they like more than the sound of their own rants)
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The interesting thing is that you are required to achieve 2 gates on the CDA. 1000' should be fully configured in the landing configuration with the Vapp within 25 knots of landing speed and reducing. The engines do not need to be spooled up to approach power by this point but they need to be stable at approach power by 500'.
A stabilized approach is when the airplane is in the landing configuration with the checklist complete, on airspeed, engines spooled up, and on the proper flight path. A stabilized approach must be established before descending below the following minimum stabilized approach heights, or a go-around is required:
• 500 feet above the TDZE during a VFR, visual, or straight-in instrument approach in VMC conditions.
• 1,000 feet above the TDZE during any straight-in instrument approach in IMC conditions.
• 500 feet above the TDZE during a VFR, visual, or straight-in instrument approach in VMC conditions.
• 1,000 feet above the TDZE during any straight-in instrument approach in IMC conditions.
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Whilst we all await any real information, I am reminded of the immortal words of the former US Defense Secretary, Donald Rumsfeld -
"Reports that say that something hasn't happened are always interesting to me, because as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns -- the ones we don't know we don't know."
Isn't that the truth?
"Reports that say that something hasn't happened are always interesting to me, because as we know, there are known knowns; there are things we know we know. We also know there are known unknowns; that is to say we know there are some things we do not know. But there are also unknown unknowns -- the ones we don't know we don't know."
Isn't that the truth?
I'm sure glad you didn't get the immortal and former words around the other way for Mr Rumsfeld.. an immortal Rumsfeld the world can do without!
A similar but shorter saying is...
Technicians know what they know, however, Engineers also know what they don't know...
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Autothrust & thrust lever positions
If A/T is operating and desired thrust is not achieved, how far do the thrust levers advance in an attempt to regain lost speed? It has been suggested that the engines did not respond to pilot action advancing of the thrust levers. It seems that the levers should already have been in an advanced position.
It is drawing a very long bow to think that the A/T was operating incorrectly AND that manually advancing the thrust levers was inneffective, as separate faults. If it was a single fault, would this point towards mechanical failure of the thrust levers? Logically this would tend to rule out fuel mishandling, fuel quality problems, fuel malfunction, engine failure etc.
It is drawing a very long bow to think that the A/T was operating incorrectly AND that manually advancing the thrust levers was inneffective, as separate faults. If it was a single fault, would this point towards mechanical failure of the thrust levers? Logically this would tend to rule out fuel mishandling, fuel quality problems, fuel malfunction, engine failure etc.
Last edited by autoflight; 21st Jan 2008 at 07:38.
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CDA approach, thrust setting at flt idle almost till stabilized.
B777, with one Autothrottle Arm Switch off, there is an Eicas Msg.
Now get this, with both Switches off together, NO Eicas msg the last time I tried. Possibly modified by now.
Could both switches be accidently knocked off without anyone noticing until the autothrottle needed to maintain speed.
Then again fm idle to full power takes 8 secs if throttle was advanced manually.
B777, with one Autothrottle Arm Switch off, there is an Eicas Msg.
Now get this, with both Switches off together, NO Eicas msg the last time I tried. Possibly modified by now.
Could both switches be accidently knocked off without anyone noticing until the autothrottle needed to maintain speed.
Then again fm idle to full power takes 8 secs if throttle was advanced manually.
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That's the most relevant thing I've read yet. Well done. Probing, and thoughtful. And well worth discussion. There were only 135 people on that plane- less than half a load. Wonder what it would have been like with a full load, and FULL baggage.
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Regarding post 170 and 'on the money posts'.
Weather was very cold at altitude during the time of the incident(SAT of -70to -72) which is right on the operating envelope for my A/C type.
Could this be of any relevance?
Binder
Weather was very cold at altitude during the time of the incident(SAT of -70to -72) which is right on the operating envelope for my A/C type.
Could this be of any relevance?
Binder
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parabellum
I suspect no fire as the bulk of the spilt fuel fell onto the wet grass and mud and by the time the airframe came to a stop there was no ignition source. Pure conjecture on my part.
I suspect no fire as the bulk of the spilt fuel fell onto the wet grass and mud and by the time the airframe came to a stop there was no ignition source. Pure conjecture on my part.
That helped no doubt, but additionally jet fuel doesn't ignite very readily unless in an aerosol form.
The lack of a single massive impact (it slowed down gradually) would have made the formation of an aerosol that much less likely.
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Ian W
That wasn't the point I was making. It was that a continuous descent at idle (if that is what occurred in this case) might have masked the problem whereas a step down to a platform altitude would have required a power-up and so revealed the problem at an earlier point in the approach. The crew would then have had the option of delaying gear/flap which might have enabled the aircraft to reach the runway.
Therefore I do not see that CDA per-se would have any bearing on this although it is possible that the BA or NATS procedures for flying them at LHR might have some impact.
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Wingswinger
A CDA is not a descent in idle, it is a continuous descent (min I believe is 500fpm) with an allowable level segment (without checking think it is 2 mile i'm sure someone will correct me).
Therefore once you are established on the glide most people will only be at approach idle to get the speed back after 4 miles, where you have invariably been maintaining 160kts.
Ergo I think CDA's have little bearing on this incident.
A CDA is not a descent in idle, it is a continuous descent (min I believe is 500fpm) with an allowable level segment (without checking think it is 2 mile i'm sure someone will correct me).
Therefore once you are established on the glide most people will only be at approach idle to get the speed back after 4 miles, where you have invariably been maintaining 160kts.
Ergo I think CDA's have little bearing on this incident.
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777 "Lost all power and avionics"?
It's so long ago now -and so many posts back - it may be worth reminding ourselves that one of the flight crew - identified as "the captain" - told the driver of a tug immediately after the crash that he'd lost "all power and avionics". No nav lights or beacons can be discerned on the footage of the approach - despite the fact that it was such a gloomy day.
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Regarding the comments about no fire. I am no expert, but I surely hope the safety experts consider the positive implications of the plane landing on soft grass rather than the hard runway. There were two benefits that I can see, it arrested the planes speed very quickly and in my view avoided a major fire due to the lack of friction that would have resulted in the fuel vapourising and igniting. In these days where excess grassed areas are being sold off to line the coffers, I really think safety experts need to stipulate a minimum amount of grassed areas to give pilots the potential to land on grass. How many times have we seen the pilots do a fantastic job of getting the plane on the ground, albeit a hard landing, and then a fireball erupting which claims the lives of most of the passengers and crew.
Last edited by ChippyChop; 21st Jan 2008 at 09:05.
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mike b
It does not mean that they know what happened!
I am not amazed that they haven't grounded the type. Since this is the first hull loss of the type in ten years, whatever caused it is rare. Secondly, to ground the type would cause more loss of money than would be caused by a hull loss with all lives. That might be harsh but it is the kind of decision that insurers and public transport companies make every day.
I too am also amazed that they havn't grounded 777's. This must mean that they do know what happened!
I am not amazed that they haven't grounded the type. Since this is the first hull loss of the type in ten years, whatever caused it is rare. Secondly, to ground the type would cause more loss of money than would be caused by a hull loss with all lives. That might be harsh but it is the kind of decision that insurers and public transport companies make every day.
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The idea that a computer or power failure could shutdown both engines
might be possible on some aircraft, but not this one.
Once lit, a normally operating Trent (or GE for that matter) will keep
running until fuel is stopped or a signal is sent to the
engine mounted FADEC box (EEC) on the 777.
Fuel:
Both the spar fuel cutoff and HMU main fuel valves are controlled in an
ELMS cabinet via relays which are hardwired to the Run/Cutoff switch.
The EEU (ELMS computer) does not command the relays nor does
any other digital devil.
EEC Shutdown signal:
The EEC can initiate a commanded shutdown only after both channels
A and B are given the reset signal, once again from
the relays controlled directly by the Run/Cutoff switches. The
channels are connected to separate relays.
Power loss will not affect the spar/HMU valve commanded positions
as these valves require power to both open and close. In addition,
the relays used for Run/Cutoff control are latching types, meaning that
a loss of power will not change relay state.
The autothrottles have been covered already. AT commands are right
in front of you - servos physically move the levers.
The 777 has no digital control link between the autothrust
computer and the engine control computers.
Throttle control inputs are powered by the EECs themselves and are
analog inputs. Each channel (A & B) has its own resolver.
So there you have it. Hardwired controls. Dual channel EECS with
dual power sources and inputs for each engine. It's a mystery.
It had been asked earlier:
An AA engineer tells me that the Trent 800 series
HMUs and EECs are manufactured by Goodrich.
might be possible on some aircraft, but not this one.
Once lit, a normally operating Trent (or GE for that matter) will keep
running until fuel is stopped or a signal is sent to the
engine mounted FADEC box (EEC) on the 777.
Fuel:
Both the spar fuel cutoff and HMU main fuel valves are controlled in an
ELMS cabinet via relays which are hardwired to the Run/Cutoff switch.
The EEU (ELMS computer) does not command the relays nor does
any other digital devil.
EEC Shutdown signal:
The EEC can initiate a commanded shutdown only after both channels
A and B are given the reset signal, once again from
the relays controlled directly by the Run/Cutoff switches. The
channels are connected to separate relays.
Power loss will not affect the spar/HMU valve commanded positions
as these valves require power to both open and close. In addition,
the relays used for Run/Cutoff control are latching types, meaning that
a loss of power will not change relay state.
The autothrottles have been covered already. AT commands are right
in front of you - servos physically move the levers.
The 777 has no digital control link between the autothrust
computer and the engine control computers.
Throttle control inputs are powered by the EECs themselves and are
analog inputs. Each channel (A & B) has its own resolver.
So there you have it. Hardwired controls. Dual channel EECS with
dual power sources and inputs for each engine. It's a mystery.
It had been asked earlier:
An AA engineer tells me that the Trent 800 series
HMUs and EECs are manufactured by Goodrich.
Controversial, moi?
Mr. Mugabe
BA B777 landing flap is F25. F30 is used on limiting runways and on one or two other situations but F25 is the usual.
At risk of ruining the thread here are a few other realities. BA SOP into LHR on an ILS would be gear taken circa 2000', usually with F20. At 1500' landing flap and final speed reduction to comply with the ATC norm of 160kts to 4DME. The engines would be at idle thrust during that speed reduction and normally spooled up again by 1000'.
As we know in the case in question the aliens took over at 600' believing Gordon Brown was on board. They were in the employ of Al Queada.
BA B777 landing flap is F25. F30 is used on limiting runways and on one or two other situations but F25 is the usual.
At risk of ruining the thread here are a few other realities. BA SOP into LHR on an ILS would be gear taken circa 2000', usually with F20. At 1500' landing flap and final speed reduction to comply with the ATC norm of 160kts to 4DME. The engines would be at idle thrust during that speed reduction and normally spooled up again by 1000'.
As we know in the case in question the aliens took over at 600' believing Gordon Brown was on board. They were in the employ of Al Queada.
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Mike B,
As Paxboy said, no, it doesn't.
I flew a 744 last night but would have been equally happy in aTripler.
Indeed I think Paxboy has it slightly wrong, IIRC this might end up being the first 777 hull loss since the type's introduction - so that's about 13-14 years.
Yes there might be a problem which will come out in the wash and which will make 777s and 787s even safer, but they've worked pretty darn well to date.
You seem to forget that the drivers and bikky-chuckers who work on them every day, also have families they want to see again and generally do not come to work with a death wish - if they are happy to climb aboard, so am I, and so should you be.
Please leave the scaremongering to the Daily Mail and its ilk.
As Paxboy said, no, it doesn't.
I flew a 744 last night but would have been equally happy in aTripler.
Indeed I think Paxboy has it slightly wrong, IIRC this might end up being the first 777 hull loss since the type's introduction - so that's about 13-14 years.
Yes there might be a problem which will come out in the wash and which will make 777s and 787s even safer, but they've worked pretty darn well to date.
You seem to forget that the drivers and bikky-chuckers who work on them every day, also have families they want to see again and generally do not come to work with a death wish - if they are happy to climb aboard, so am I, and so should you be.
Please leave the scaremongering to the Daily Mail and its ilk.
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but I surely hope the safety experts consider the positive implications of the plane landing on soft grass rather than the hard runway.
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Electronis or fuel...
"From the accounts so far it appears as though the most likely reason for the problem was either engines, electronics or fuel" (quote)
I would eliminate the engines as an option. It is basically impossible the two totally independent engines failed to respond, at exactly the same time, after many hours of perfect functioning.
It will be possibly a fuel related issue or an electronic/software glitch (which started earlier along the wires, not far from the cockpit) or a combination of these two factors. Software/Hardware within the engines cannot fail simultaneously instead (e.g FADEC).
This incident has sent a few strong messages out (in my modest opinion):
-Grass before/after/around the runway is essential, especially in RESA. The 27L RESA saved this 777 and we have had a few incidents in the last few years where RESA (combined to pilot's skills or errors) saved lives.
Modern aircrafts have very strong and flexible structures, they can definitely survive a crash-land on grass: RESA regulations/limitations should be possibly be reviewed on all runways and extended whenever possible. Some very profitable car parks will have to be moved (e.g. the one just in front of 27R! at EGLL).
On some aircraft types the windows on doors, where Cabin Crew sit (e.g. on Boeing 767, 777), are extremely small (it is impossible to see outside! Try it!) whilst CC should be able to see what is happening outside in emergencies,they can be in charge of an evacuation when pilots are unable to PA. On this 777 pax told CC what was going on outside. This is in my opinion unacceptable and you can waste valuable seconds.
Ground-Cameras should be installed on all approaches, capable of recording all final approaches and touch down: the cost of this is nowdays extremely low and they would really help an investigation.
The Pilots did an excellent job. Well done. Pilots skills, RESA and the 777 solid structure saved many lives at EGLL...
I would eliminate the engines as an option. It is basically impossible the two totally independent engines failed to respond, at exactly the same time, after many hours of perfect functioning.
It will be possibly a fuel related issue or an electronic/software glitch (which started earlier along the wires, not far from the cockpit) or a combination of these two factors. Software/Hardware within the engines cannot fail simultaneously instead (e.g FADEC).
This incident has sent a few strong messages out (in my modest opinion):
-Grass before/after/around the runway is essential, especially in RESA. The 27L RESA saved this 777 and we have had a few incidents in the last few years where RESA (combined to pilot's skills or errors) saved lives.
Modern aircrafts have very strong and flexible structures, they can definitely survive a crash-land on grass: RESA regulations/limitations should be possibly be reviewed on all runways and extended whenever possible. Some very profitable car parks will have to be moved (e.g. the one just in front of 27R! at EGLL).
On some aircraft types the windows on doors, where Cabin Crew sit (e.g. on Boeing 767, 777), are extremely small (it is impossible to see outside! Try it!) whilst CC should be able to see what is happening outside in emergencies,they can be in charge of an evacuation when pilots are unable to PA. On this 777 pax told CC what was going on outside. This is in my opinion unacceptable and you can waste valuable seconds.
Ground-Cameras should be installed on all approaches, capable of recording all final approaches and touch down: the cost of this is nowdays extremely low and they would really help an investigation.
The Pilots did an excellent job. Well done. Pilots skills, RESA and the 777 solid structure saved many lives at EGLL...