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There have been several references to the Ethiopean 767 crash. It appears some think this was a controlled ditching. It was a higher speed impact with the water while the crew was engaged in a ongoing struggle with the hijackers right up to the moment of impact. It was not a controlled ditching.
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Engines
What chance would engines have remaining attached in a 3 second period flat spin? Pylons don't appear to be made to tolerate many lateral g's.
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Further to Ian W's comment:
Please excuse my ignorance, but do we have any evidence at this stage of any 'concertinering' of the fuselage or of any injuries (post mortem) other than broken limbs ?? Perhaps I've missed some latest photographs ?? |
A couple of things...
First, it's so good to see some of the real professionals and experts back posting after so many have been quiet since the halcyon days of pprune (the AF447 threads come to mind of course). You -- and long time ppruners -- know who you are. Second, whatever the cause(s) of this accident, the aircraft did not "explode" or come apart at altitude. A transport category jet aircraft without tail surfaces does not / cannot impact the surface in a near flat or near horizontal attitude. It would impact (whatever surface) nose first and at a vey high rate of descent. Very few large intact pieces would remain. Lastly, as others have said in rebuttal to negative comments (including some slurs) against the Indonesians, their SAR, their ATC, and their investigative agency: Those of us Bules (Bahasa for foreigners) who have worked with them and for them recently agree that painting them as inept and/or corrupt is simplistic and inaccurate. The level of professionalism and commitment to improvement over the past few years is clear and obvious to other governments, ICAO, international corporations and individual aviation experts. |
A number of posts trying to find alternative explanations, many without due regard to the photographic evidence posted earlier in the thread, the basic laws of physics and how one should fly a modern jet aircraft.
Not in any particular order, no blame or insult is intended: Vertical dive into sea. A.Take an empty drink can and with the can on its base stamp on it. B. Take another empty can lay it on its side and stamp on it. Do the fusalage photos look like a or b? Answer b. Therefore it can be infered that the plane hit the sea more or less horizontally. Ditching. You do not lose speed by banking the aircraft. Ditching configuration varies acording to aircraft type but for all aircraft one should land parallel to the swell line with some degree of nose up attitude and wing level. The time frame available is usually short enough that getting this right is very difficult. C. Take yet another empty drinks can and scrape it horizontally along some rough concrete. (The sea will be as friendly to an aircraft). Does the can look anything like the photos? Answer no. Inferance is therefore ditching very unlikely. Please dispose of your cans in an environmentally friendly manner. |
The Economic Times reports:
SINGAPORE: Singapore's search operation to locate the debris of the crashed AirAsia plane came to end today with its ship that found the jet's fuselage in the Java Sea returning back after days of rigorous scouring.
Singapore's Navy ship, MV Swift Rescue, with 70 men and women on board, arrived at Changi Naval Base here and was received by the country's Defence Minister Ng Eng Hen. He was accompanied by chief of Defence force Ng Chee Meng and navy chief Lai Chung Han. The arrival of MV Swift Rescue marked the official end of Singapore's efforts in the multi-nation search operation, which started on December 28 when AirAsia plane carrying 162 people from Indonesian city of Saurabaya to Singapore crashed into the Java Sea within less than an hour after take off. Since then, the Singapore Armed Forces (SAF) have deployed more than 400 personnel, two RSAF C-130 aircraft, two Super Puma helicopters, five navy ships and a six-man Autonomous Underwater Vehicle team in the operation. Many of those who had contributed to the search were also present for MV Swift Rescue's home-coming. As a mark of respect, they observed a minute of silence for those who died in the aviation tragedy. The Defence Minister thanked the servicemen and women for their efforts and for making a difference in the multi-nation search operations. The return of the vessel marks the end of the SAF's 22-day deployment for the search operations, he said. |
Mindboggling stuff, as bad as advanced sailing theory. So presumably non of the boundary conditions for any of these swapover points are known for the A320, and so there is no way of knowing exactly when and how it will stall and or spin? especially if you include such things as changing CofG, weather etc.
If I recall the test regime for the 380 (I guess the 320 was similar) that consisted mostly of slowly going slower and slower as well as faster and faster until things got obviously dangerous, ceasing before you crashed and telling the computer not to let the AC go there. That with the background of fairly low g loading limts for the airframe which would make many escape strategies impossible anyway. |
Automated Spin Response
If it turns out to be a spin then Airbus should deeply think about an automated response by the flight control computer. The pilots have no realistic chance to break a full spin action. However the computer most likely can and has usually an easy and safe indication from the gyro instruments. If it takes 10000 feet so be it given the alternative of an assured crash. Who is going to do the test flights to supply the necessary data to ensure that the programmed response is correct in all situations? That would be a very expensive and arguably fatal endeavour. If that data is not available, and HAL is programmed for a theoretical/simulated response who is going to do the testing necessary for certification ? I'm sure that Airbus has thought of such an 'adventure' during planning and totally rejected the thought for obvious reasons - similar thinking for a full stall. Now you know why Airbus puts so much emphasis on avoidance. |
At least QZ 8501 had less kinetic energy in the vertical direction |
stall testing transport jets
I am quite sure this is true for any modern large transport certified after the 70s. B787: https://www.youtube.com/watch?v=SvEMgmirldc Includes interview with Boeing chief test pilot MD11: 1990: MD-11 Memories | Things With Wings The stall test comments come at the very end of the report |
cogito ergo sum
If you believe (and told so) that your aircraft is protected from stall, you may not avoid it as actively as if you know it can kill you… You may not avoid it as actively and you may not know how to recover from it. Bottomline it is difficult to say, if the computer protection has saved more lives than its presence has lured management and pilots into negligence regarding their skills of handling the aircraft at the borderlines of aerodynamics and costing lives in the process. |
If it turns out to be a spin then Airbus should deeply think about an automated response by the flight control computer. The pilots have no realistic chance to break a full spin action. However the computer most likely can and has usually an easy and safe indication from the gyro instruments. If it takes 10000 feet so be it given the alternative of an assured crash. |
Why is ther so much discussion about stall spin? Have a missed a statement ?
The aircraft looks fairly intact almost as if it was in a semi controlled state when it went in, the pictures of the af447 wreckage look a lot different |
AT what point in the crash do you think the tail separated from the fuselage?
The reason I ask I assume when the tail separated, the CVR and FDR went with it and and that will be the last data recorded. |
CVR
Some information regarding the content of the CVR:
When asked if there was any evidence from the recording that terrorism was involved, Hananto said: “No. Because if there were terrorism, there would have been a threat of some kind.“ “In that critical situation, the recording indicates that the pilot was busy with the handling of the plane.” Investigators said they had listened to the whole of the recording but transcribed only about half. “We didn’t hear any voice of other persons other than the pilots,” said Nurcahyo Utomo, another investigator. “We didn’t hear any sounds of gunfire or explosions. For the time being, based on that, we can eliminate the possibility of terrorism.” |
"...the pilot was busy.."
Perhaps only one pilot in the cockpit at the critical moment? |
More info re CVR:
"From the (flight data recordings) so far, it's unlikely there was an explosion," Hananto said. "If there was, we would definitely know because certain parameters would show it. There are something like 1,200 parameters." The final minutes of the AirAsia flight were full of "sounds of machines and sounds of warnings" that must be filtered out to get a complete transcript of what was said in the cockpit, said Hananto, who has been an air safety investigator since 2009. The first half of the two-hour long cockpit voice recording has been transcribed. That includes audio from the previous flight and the beginning of Flight QZ8501, which crashed around 40 minutes after takeoff. The team, which is working with French, Singaporean and Chinese air safety investigators, hopes to finish transcribing the recording this week, Hananto said. With seven computers and various audio equipment, the small NTSC laboratory dedicated to the AirAsia investigation is split into two rooms; one for the cockpit voice recorder and the other for the flight data recorder. Analysis of the flight data recorder would take longer, Hananto said, because investigators were examining all 72 previous flights flown by the aircraft. Investigators hope to finish a preliminary report on the crash early next week. The full report could take up to a year, but will not include the entire cockpit voice transcript. "In Indonesia it remains undisclosed," said Tatang Kurniadi, chief of the NTSC. "Just some important highlights will be included in the report." Nurcahyo Utomo, another investigator from Indonesia’s Transportation Safety Committee, said nothing heard on the audio recording so far suggested pilot suicide played a role in the crash. “So far we’ve managed to transcribe only half of it because there are so many noises,” he said. “We hope to complete it in a week.” |
Perhaps only one pilot in the cockpit at the critical moment? “We didn’t hear any voice of other persons other than the pilots,” |
Originally Posted by FullWings
(Post 8831189)
Problem with that is that from past evidence, unusual attitude / loss-of-control has occurred because the automated systems have given up due to conflicting/unverifiable data and dumped the whole lot back on the pilots to make something of it. If it is possible to get the aeroplane to “self recover” from spins, etc. then there is enough information to stop it happening in the first place, which I would suggest is the prime goal.
The spin self-recovery could be a basic protection that is not lost. As it can use GPS Alt, and Inertial Nav to identify the aircraft is dropping fast and rotating in a particular direction. Then the system takes over and carries out the recovery. Entry into a stalled/spin condition could be extremely fast in severe turbulence at cruise level with sudden wind reversals and OAT changes and yes even pilot mishandling. In some cases there may be no gentle and considered 'approach to stall'. |
I think the continuous references to "HAL" have misled some people into thinking that the Airbus flight control system is far more capable, in the sense of intelligent, than it is. It's actually fundamentally very conservative in design, only flies the aeroplane itself in quite benign parts of the flight envelope, and uses simple rules (albeit perhaps in too many combinations for some peoples' tastes) for its protections. It would be a massive change to give it the capability to reliably identify spins, quite possibly in the presence of sensor failures or anomalies, and then somehow act like the autopilot to end all autopilots in recovering from that spin, without the benefit of prior data on spin characteristics and best recovery methods. It's not going to happen, at least anytime soon.
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As posted above the Airbus has a very basic FBW system. Spins have so many modes and types that it can be very difficult to identify if the aircraft is spinning and what mode. Even more advanced FBW systems incorporating rate motion feedback can't recover from a spin. In fact the most important step in spin recovery for the F18A was to disconnect the FBW computers and go to direct electrical link. The Airbus does not allow pilot selection of that option.
You would also have to do extensive spin testing on the aircraft in order to determine the proper recovery inputs for each spin mode and CG situation. |
Analysis of the flight data recorder would take longer, Hananto said, because investigators were examining all 72 previous flights flown by the aircraft. That includes audio from the previous flight and the beginning of Flight QZ8501, which crashed around 40 minutes after takeoff. Overall it looks like some more professional people are now on the job. The Statements given do make much more sense than previous ones... |
Heavy Metallist: bravo.
There are problems with protections and envelope constraints: they rely on fallible sensors for their information. So, back to "Data Processing 101" : Garbage In= Garbage Out. True in 1971, doubly so now. For the uninitiated- the aeroplane relies on its flight control software to implement the control laws complete with protections to address the needs of 99.99X% of all flights. On a very very few flights the sensors get compromised, all of the laws, protections and load relief goes away and the now betrayed crew is left with a lightweight, flexible, undamped aeroelastic, auto trimming nut case with a one-eyed determination to save the day by diving or stalling the aeroplane into the ground. Bad sensors. Like bad rumours, mixed up lab results and WMD intelligence, they lead to grave misjudgements and irrevocable error. The problem of an uncrashable aeroplane is the same as an unsinkable ship: The crew has to politely smile at the marketing, understand its limitations and, if called, be able and willing to step up and act like an old fashioned master, not someone who is just along for the ride. (EMPHATICALLY NOT SUGGESTING THIS IS THE CASE WITH THE ACCIDENT FLIGHT, by the way. But I suspect that it is an industry problem. ) The flight guidance system at this stage is too rudimentary to provide guidance out of unusual attitudes. That's the stuff that we are supposed to be experts at after 15 or 20 minutes of training every couple of years. Oh...and the mythical aerobatic experience as a teenager followed by the fighter training and pylon racing, I guess. Since recovery from inappropriate energy states and attitudes is actually pretty binary it might be possible to quickly develop a recovery guidance mode to facilitate the lowest common denominator crew** to follow prompts or director cues to the correct attitude to regain normal flight paths and loads. That would be the missing half of the promise that fly-by-wire makes: (This aeroplane is not stallable. If, however, you do stall it, it will tell you how to undo your error) **: this is relative, obviously. Any one of us could be the lowest common denominator depending on skill, experience, fatigue and other intangibles on the day. To recap: 1:FBW is a huge improvement on the pieces of sh1t that I used to fly when I was a zygote. So is almost everything else 2:FBW has probably reduced the incidence of serious incident by at least an order of magnitude. (And hence the accident rate is equally reduced) 3: Auto flight, at least on the approach, is not as smooth as the hypothetical experienced, well rested crew. 4:Like all numerically controlled machines, modern aeroplanes rely on sensors. Lots of them. They are lightweight, built to a price, and they fail from time to time. 5:Spurious warnings, cautions and whatnots are far more common that real ones. 6:Spurious alarming data is not immediately distinguishable from actual alarming data. 7:Active protections can save passengers from random dumb crew mistakes. 8:Spurious protection triggers can expose passengers to random dumb designer mistakes. (Too trusting of sensors without appreciating the "what if" hypothetical scenarios. Which happen from time to time) 9:"Golden Rule" instructions are all predicated on the presence of a very experienced, jaded yet competent crew to fly manually like a conventional aircraft when any unexpected or sub-optimum performance is demonstrated by the automatics, however subtle. On edit, added: 10: the altitude capture mode, called "Alt star" presents peril when it engages during a high rate of climb manoeuvre. It locks in the current rate of climb, in this case, if it engaged, at over 1000 ft below the target altitude. If the wind shear dissipates and or the updraft fails, the aircraft will be left with a rapidly decaying airspeed and an autopilot disconnect at high alpha. (At my peak I used to manually fly 1000+ hours every year. On raw data. While doing star shots and smoking black coffee and drinking unfiltered Luckies. And listening to disco music on the ADF receiver. While keeping an eye on that pesky number 13 cylinder on number two. Today I get about three minutes of manual flying per week. I am considered a thrill-seeker for doing that much. Incredibly, an entire industry has grown on the convenient lie that the old skills, if ever attained, remain honed after decades of neglect. |
Entire industry grown on a convenient lie
One of the most educated and intelligent posts read on this forum. But what of the folks who were /are NEVER even taught the "old skills...?"
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In this world, the whole point of flight control software is to make planes cheaper by making pilots cheaper, giving manufacturers something to contrast them with the competition.
Training pilots properly AND having sophisticated flight control software makes no financial sense. |
9:"Golden Rule" instructions are all predicated on the presence of a very experienced, jaded yet competent crew to fly manually like a conventional aircraft when any unexpected or sub-optimum performance is demonstrated by the automatics, however subtle. As others are saying, FBW and envelope protection has likely saved many more lives than ended them but we are getting to the point that experience levels (that is experience in directly controlling an aircraft in all flight phases) have deteriorated such that: a) realising something’s not right takes some time, b) working out what might be done about it takes yet more time and c) actually taking the aircraft by the scruff of the neck and putting it roughly where it should be has become a HUGE decision accompanied by much trepidation. I was in the sim yesterday and did a couple of unreliable airspeed scenarios. Taking out the FBW after the initial diagnosis made it so much easier, as the aeroplane was no longer actively trying to kill you. |
Volume
They'll be going all the way back in the FDR to check for previous malfunctions of systems as well as to see if anything else may have played a role I.E. unreported heavy landing etc that may have weakened the structure
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@Australopithecus
Australopithecus nice post :-)
...to address the needs of 99.99X% of all flights. On a very, very few flights the sensors get compromised,... Could we say that 'trip optimalization' is for the 99.99X%. And that for the other (100-99.99X%) we sincerely need to revisit, redefine and retrain pilots 'flying skills optimalization'. Is there an open source publication that compares the actual trip optimalization performance of low, medium and highly experienced pilots? Would be interesting to hear your views on these two questions. |
Recorder investigation
AirAsia crash not the result of terrorist attack | Video | Reuters.com
FYI the Reuters article has a short video in the lefthand corner showing the KNKT lab and a very short interview with one of the investigators. |
The final minutes of the AirAsia flight were full of "sounds of machines and sounds of warnings" that must be filtered out to get a complete transcript of what was said in the cockpit That's a old story ..... Now investigators thanks to the analysis of the FDR will be able to sort these warnings and know which ones were appropriate and which were inappropriate Will the pilots have the means or knowledge to do this sorting in fews minutes ? |
I do wonder if the situation with ECAM can sometimes be likened to having a padlock in front of you, ie the actual problem that's occurring, and you're handed a bunch of keys and have to try each in turn before you get to the correct one.
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5:Spurious warnings, cautions and whatnots are far more common that real ones. 6:Spurious alarming data is not immediately distinguishable from actual alarming data. It can by definition not be distinguishable, otherwise it would not be alarming. Unfortunately non useful reactions are 1) panic or 2) ignore it 3) decide it is "spurious" - in any order. Useful reactions one assumes are part of the type training of pilots. c) actually taking the aircraft by the scruff of the neck and putting it roughly where it should be has become a HUGE decision accompanied by much trepidation. 8:Spurious protection triggers can expose passengers to random dumb designer mistakes. (Too trusting of sensors without appreciating the "what if" hypothetical scenarios. Which happen from time to time) |
DrPhillipa
Why the Bus can not default to sensible neutral values of thrust and pitch (and trim maybe) before dumping it on the pilots I do not know It does not "dump" on the pilots... In alternate law thrust is locked at current value until PF takes over manually, pitch law remains (with auto-trim) the same (1g stick free so no pitch change if you leave it alone), except you lose protections in the event of high speed, high alpha, and big pitch excursions, roll law degrades to direct control of ailerons and spoilers. If it goes to direct law then you have direct control of elevators as well, and must use manual pitch trim. In all laws the a/c remains completely controllable by flying attitude. |
Post AF447
An A330 driver was telling me of the new sim exercise at high altitude with sensors gone u/s.
As per current drill, he switched off the automatics and set pitch and thrust manually. The instructor then had him restore autothrust. A/T decided there was an overspeed, reduced thrust and things went downhill from there. During the AF447 discussion, I was wondering when AB would flight test a high altitude stall as it could provide important information to the investigation. With drone technology, the tests could be flown from the ground. |
Quote/...
Post AF447 During the AF447 discussion, I was wondering when AB would flight test a high altitude stall as it could provide important information to the investigation. With drone technology, the tests could be flown from the ground. .../unquote. The Concorde prototypes had a crew escape hatch CONCORDE SST : Duxford Internal Pictures Possibilities.... |
I am far from convinced that there are many "spurious protection triggers" or "dumb designer mistakes". No, I am not a pilot, but I have been intimately involved in real time safety critical software design, realisation and testing. I am a pilot and I can testify to the thousands of spurious faults and messages an A320 comes up with. Most of the time Ctrl/Alt/Delete does the job. Sometimes sadly there is no time for that sort of thing. A humble attitude and a very heavy dose of realism is an essential attribute of any engineer dealing with safety critical systems |
TyroPicard:
So many posters know diddly-squat about A320 FCS.... if you don't know why post? |
c) actually taking the aircraft by the scruff of the neck and putting it roughly where it should be has become a HUGE decision accompanied by much trepidation. On two recent flights I’ve observed otherwise competent pilots watching the speed rapidly bleed off due to a high-rate altitude capture. At that point, no FMC or MCP skills are going to help, you’re in a pre-programmed trajectory. It’s AP out and I had to hint several times as many people are reluctant/uncomfortable/unhappy doing this at altitude. If nasty things start happening up near the top of the flight envelope, e.g. you are rapidly approaching the definition of a “jet upset”, gently and carefully could be your undoing as it may take pitch/roll attitudes and control deflections that you’ve never used before outside the simulator (and maybe not even in there) in order to recover. See AF447. The QF A380 was a fine example of CRM and technical skills saving the day but they were not fighting the aeroplane for control. (In the above quote “roughly” was meant as “approximately” rather than crudely or violently.) |
" In fact the most important step in spin recovery for the F18A was to disconnect the FBW computers and go to direct electrical link. "
Of course, the point was, that the pilots of most airliners are far enough from the center of gravity, where, in a spin, it is more like the infamous "G machine" centrifuge, astronauts trained in, than an F18A. The pilots of the larger airliner, can not take control because the G's keep their hands pinned. Although I think it's a good idea worth looking into, maybe an automation cure is worse than the disease. Instead of automation to get out of flat spin, maybe more training, to not get there in the first place, is a better use of resources. Maybe some resources to both. Doesn't always need to be either/or. |
Ian and Machinbird
I don't know how applicable would be to the AF A330 scenario, but back during the original 777 flight testing, there was a story going around (from normally reputable sources) that an FAA pilot had inadvertently gotten a 777 into a deep stall at high altitude. The Boeing pilot promptly took over and was able to recover the airplane but the resultant altitude loss was "well over 10k". I can't personally vouch for the accuracy of the story (friend of a friend type stuff) - and assuming it did indeed happen it was kept pretty quiet (no news reports that I'm aware of). BTW, again, not sure how applicable to how Brand A does things, but Boeing routinely does stall testing of its new aircraft, although not extreme deep stall scenario. Back in the late 1980's I was onboard for many hours of stall testing on a 767. Granted, fairly benign stalls (hold altitude, let the speed drop until the wing stalls and let it fall out of the stall and recover). Also, "windup turns" - used to test inlets at high airflow/high AOA (perform a constant altitude turn with engines set to the desired power, then keep pulling the turn tighter until the aircraft stalls and falls out of the turn). Such testing was always done in daylight in clear air - and during one preflight I recall a request that the flight test pilot "avoid" using the rudder when recovering from the stall, as large rudder swings could slice off the trailing cone which would end the test day. The pilot rather roughly responded that he was going to do whatever he felt necessary to recover the airplane :ok: |
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