Flaperon washes up on Reunion Island
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A non violent impact or a "Sully ditching" would imply a calm sea, nose-up attitude between 5 and 10 degrees and low rate of descent. That could only be achieved with the slats and flaps extended
Last edited by Gysbreght; 23rd Aug 2015 at 17:15.
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FTR...The actual computed acceleration value was 0.68 Gs. There is no point debating the precise accuracy of these numbers. The only important take-away is the fact that even if the 2 final BFO numbers are off some, say 20 or even 50 Hz due to unaccounted for error, the descent rates implied by the final 2 BFO values are very high, exactly as we observed in the simulator. In addition, via pvt correspondence with a high level official at ATSB, I learned that Boeing observed similar post fuel exhaustion descent profiles.
One more point: There is not a single piece of evidence or theory that has been suggested to explain why the final 2 BFO values would not be as good as all the others used in the analysis by Inmarsat, ATSB, the IG, and everyone else that has modelled the path. There were relatively small BFO errors at 16:00 immediately following that reboot (~17 Hz) and we suspect a similar level of error likely immediately following the 18:25 reboot, but compared to the ~250 Hz change at 00:19:37, a post boot up error of 17 Hz or so is insignificant in the bigger picture: It was descending very fast!
One more point: There is not a single piece of evidence or theory that has been suggested to explain why the final 2 BFO values would not be as good as all the others used in the analysis by Inmarsat, ATSB, the IG, and everyone else that has modelled the path. There were relatively small BFO errors at 16:00 immediately following that reboot (~17 Hz) and we suspect a similar level of error likely immediately following the 18:25 reboot, but compared to the ~250 Hz change at 00:19:37, a post boot up error of 17 Hz or so is insignificant in the bigger picture: It was descending very fast!
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AirLandSeaMan- thank you very much. The sequence of events you listed from the simulated fuel exhaustion is enlightening, and fits well enough with the Inmarsat data and flaperon condition to make it the most probable scenario at present. I think it was 9 days before they even STARTED searching for debris off Australia, enough time for it to disperse and sink. Nothing was ever found from the 1979 Varig Boeing 707-323C disappearance 110 nm ENE from Tokyo, for example, a much easier and more timely search.
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VARIG LOSS info
https://en.wikipedia.org/wiki/1979_B..._disappearance
now this is the things movies are made of.
also wondering where my posts have gone? perhaps a moderator could tell me why they don't show up. I even started a thread and now my log in name isn't there.
There seems to be an interesting question about "clean" ditching and speeds involved. I don't have the numbers handy, maybe someone else does, but What is the clean maneuvering speed for this 777 with zero fuel?
now this is the things movies are made of.
also wondering where my posts have gone? perhaps a moderator could tell me why they don't show up. I even started a thread and now my log in name isn't there.
There seems to be an interesting question about "clean" ditching and speeds involved. I don't have the numbers handy, maybe someone else does, but What is the clean maneuvering speed for this 777 with zero fuel?
The lone flaperon...
Quote from Gysbreght:
"I agree that a "Sully ditching" requires a conscious pilot and a benign seastate. Furthermore, that pilot must be able to think beyond normal procedures and to anticipate what is required for a successful ditching with engines out. However, a nose-up attitude between 5 and 10 degrees and low rate of descent can be achieved with the slats and flaps retracted."
Hi, I think you were quoting from Phoenix's post of just under 3 hours ago? A pitch attitude of 5 -10 degrees and a low vertical speed is perfectly achievable with a "clean" a/c, as you say. (Jet airliners do it routinely, going into holding patterns.)
The problem for ditching with no high-lift devices is that the sea-level true airspeed is likely to be at least 200 knots, even at the empty-tank weight with a load of pax (afraid I don't have any B777-200 performance figures to hand). In still air, that gives a ground speed over 50% higher than the same pitch with slats and flaps in the landing configuration, meaning well over double the kinetic energy. Unless the ocean was as glassy as the Hudson River (implying no wind...) the a/c would certainly break up.
That's part of the problem for the experts who speculate that the only piece to detach from the a/c was the flaperon. As I posted about 34 hours ago:
"More likely, they are speculating that it was set down in a controlled fashion at something like a normal approach speed.... that would also imply a fairly calm sea, wings level, nose-up pitch somewhere between 5 and 10 degrees, and low rate of descent. That could only be achieved with human intervention, and probably with both the slats and flaps extended. If they were, they would be that much more likely to have been torn off."
Also, why would the experts' lone item of floating debris happen to be washed up on an island which is merely a speck in the Indian Ocean? Far more likely eventually to arrive on the eastern coasts of Madagascar, Kenya, Tanzania, or Mozambique. My guess is that, assuming it is from MH370, it was one of many floating objects. If funds and resources were available, those long coasts would be the areas to search.
"I agree that a "Sully ditching" requires a conscious pilot and a benign seastate. Furthermore, that pilot must be able to think beyond normal procedures and to anticipate what is required for a successful ditching with engines out. However, a nose-up attitude between 5 and 10 degrees and low rate of descent can be achieved with the slats and flaps retracted."
Hi, I think you were quoting from Phoenix's post of just under 3 hours ago? A pitch attitude of 5 -10 degrees and a low vertical speed is perfectly achievable with a "clean" a/c, as you say. (Jet airliners do it routinely, going into holding patterns.)
The problem for ditching with no high-lift devices is that the sea-level true airspeed is likely to be at least 200 knots, even at the empty-tank weight with a load of pax (afraid I don't have any B777-200 performance figures to hand). In still air, that gives a ground speed over 50% higher than the same pitch with slats and flaps in the landing configuration, meaning well over double the kinetic energy. Unless the ocean was as glassy as the Hudson River (implying no wind...) the a/c would certainly break up.
That's part of the problem for the experts who speculate that the only piece to detach from the a/c was the flaperon. As I posted about 34 hours ago:
"More likely, they are speculating that it was set down in a controlled fashion at something like a normal approach speed.... that would also imply a fairly calm sea, wings level, nose-up pitch somewhere between 5 and 10 degrees, and low rate of descent. That could only be achieved with human intervention, and probably with both the slats and flaps extended. If they were, they would be that much more likely to have been torn off."
Also, why would the experts' lone item of floating debris happen to be washed up on an island which is merely a speck in the Indian Ocean? Far more likely eventually to arrive on the eastern coasts of Madagascar, Kenya, Tanzania, or Mozambique. My guess is that, assuming it is from MH370, it was one of many floating objects. If funds and resources were available, those long coasts would be the areas to search.
Last edited by Chris Scott; 23rd Aug 2015 at 20:32. Reason: Last paragraph extended. Reference to ground speed added.
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Hi Chris:
Welcome to the discussion and thank you for your as usual well-informed contribution. Of course I am well aware of the fact that the landing speed in a flapless landing is much higher than in the normal landing configuration Flaps30. I won't quibble with your numbers, although the actual figures aren't quite as bad as your estimates. By far the most important factor is the rate of descent at impact with the surface, with attitude a close second. Ideally V/S should be zero, as in a 'greased' landing on a runway. In the "benign seastate" that I mentioned the kinetic energy is of lesser importance. There is unlimited 'runway length' available to absorb it.
Welcome to the discussion and thank you for your as usual well-informed contribution. Of course I am well aware of the fact that the landing speed in a flapless landing is much higher than in the normal landing configuration Flaps30. I won't quibble with your numbers, although the actual figures aren't quite as bad as your estimates. By far the most important factor is the rate of descent at impact with the surface, with attitude a close second. Ideally V/S should be zero, as in a 'greased' landing on a runway. In the "benign seastate" that I mentioned the kinetic energy is of lesser importance. There is unlimited 'runway length' available to absorb it.
Hi Gysbreght,
Sorry, it's hard to know what the other guy knows on this forum - in some cases, not much! We seem to be broadly in agreement, but is the concept of a glassy sea plausible?
Sorry, it's hard to know what the other guy knows on this forum - in some cases, not much! We seem to be broadly in agreement, but is the concept of a glassy sea plausible?
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Far more likely eventually to arrive on the eastern coasts of Madagascar, Kenya, Tanzania, or Mozambique. My guess is that, assuming it is from MH370, it was one of many floating objects. If funds and resources were available, those long coasts would be the areas to search.
but is the concept of a glassy sea plausible?
It is not obvious what benefit the search for additional debris might bring.
Wreckage does not help clarify the cause or the location of the accident, just the nature of the final ditching.
Airlandseaman argues convincingly and with factual evidence that the aircraft went down without pilot intervention, a Helios like flight into nowhere, with a high speed crash at the end.
To perhaps find out what brought that about the authorities would need to find the CVR and FDR. Unfortunately, assuming the simulation is reasonably valid, the wreckage is unlikely to include any large pieces. That lengthens the odds against finding the crash site.
Wreckage does not help clarify the cause or the location of the accident, just the nature of the final ditching.
Airlandseaman argues convincingly and with factual evidence that the aircraft went down without pilot intervention, a Helios like flight into nowhere, with a high speed crash at the end.
To perhaps find out what brought that about the authorities would need to find the CVR and FDR. Unfortunately, assuming the simulation is reasonably valid, the wreckage is unlikely to include any large pieces. That lengthens the odds against finding the crash site.
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Let's not get carried away. There's very little factual evidence, some of which are under dispute (e.g., the last Inmarsat data point).
So there are many plausible scenarios -- with or without pilot intervention -- which can be made to fit the available data depending on how one chooses to interpret the data.
Also, even a Cat D simulator is not an engineering simulator. A Cat D simulator is only designed to provide fidelity for line operations within a specific flight envelope. Generally that means bank angles < 45 degrees, nose attitude no more than -10 deg down or +25 deg up, and airspeeds within the aircraft's normal operating range. Anything outside of that and you have to be very careful to cross-check against the simulator's validated flight envelope (e.g., using alpha-beta plots, etc.).
That is why a Cat D simulator can only provide limited stall / upset recognition and recovery training. Yet here we're talking about speeds exceeding Mach 1, 80 degree bank angles, 15,000 fpm descents, etc.
Those figures are well past the parameters of line simulators, and it would be a crap shoot whether the behavior seen have any semblance with reality or not.
So there are many plausible scenarios -- with or without pilot intervention -- which can be made to fit the available data depending on how one chooses to interpret the data.
Also, even a Cat D simulator is not an engineering simulator. A Cat D simulator is only designed to provide fidelity for line operations within a specific flight envelope. Generally that means bank angles < 45 degrees, nose attitude no more than -10 deg down or +25 deg up, and airspeeds within the aircraft's normal operating range. Anything outside of that and you have to be very careful to cross-check against the simulator's validated flight envelope (e.g., using alpha-beta plots, etc.).
That is why a Cat D simulator can only provide limited stall / upset recognition and recovery training. Yet here we're talking about speeds exceeding Mach 1, 80 degree bank angles, 15,000 fpm descents, etc.
Those figures are well past the parameters of line simulators, and it would be a crap shoot whether the behavior seen have any semblance with reality or not.
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...but is the concept of a glassy sea plausible?
Why the East River - what about JT @ DPS
Instead of looking only at the "Sully ditching" as an indicator of how an aircraft might survive a ditching, consider the "Lionair landing" at DPS the other year (still haven't seen any final report for that one either).
But that was a largely-uncontrolled ditching, in landing configuration into a disturbed sea (refer tropical storm at the time of the incident).
I am not 100% certain of the details but seem to remember flaps as still being attached, just engines missing.
I would just about guarantee a nose well up attitude as he hit the water, especially with the sea wall filling the windshield.
But that was a largely-uncontrolled ditching, in landing configuration into a disturbed sea (refer tropical storm at the time of the incident).
I am not 100% certain of the details but seem to remember flaps as still being attached, just engines missing.
I would just about guarantee a nose well up attitude as he hit the water, especially with the sea wall filling the windshield.
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I'm told “derive plonge entre deux eaux” literally means drifted plunged between 2 waters.
Selon un expert aéronautique toulousain qui a requis l'anonymat, l'élément de la voilure n'aurait pas flotté pendant plusieurs mois à la surface de l'eau mais aurait dérivé, plongé entre deux eaux à quelques mètres de profondeur.
According to an aeronautical expert form Toulouse (actually a Toulousian) who wished to remain anonymous, the flaperon would not have floated for many months at the surface but would be between two areas (seas, possibly surface and bottom, or even currents?) at some metres depth
Rob
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If you Google you'll find that "entre deux eaux" appears quite often. It seems to be an idiom. Several PADI diving schools use the term in their names or business description.
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Check for "thermocline". As divers in Florida we regularly dove through a field of vegetation debris held some depth below the surface, passing between quite warm and quite cold water as we did so. The layer of debris is narrow. The temperature difference is quite remarkable.
Quotes from 172driver:
"Having worked in southern and eastern Africa for years, let me tell you that any bigger piece of debris would be re-used. A flaperon makes a perfect piece of roof, seats are, well, seats, etc. [...] What would be needed now is an awareness campaign (together with financial reward) along these coasts."
Yes indeed. A mammoth task, but at least the talk of money spreads fast - even without phones and the internet.
"That the flaperon washed up on Reunion, which is French and therefore rather well organized, was pure and utter luck."
If, as the experts seem to be suggesting, it were the only piece of floating debris from MH370, I would agree emphatically. If there were dozens, it would still rank as remarkably fortunate, IMO.
"I am reasonably certain that there is more debris being washed ashore..."
Assuming the flaperon is from MH370, it seems inevitable - unless the sea was freakishly smooth where the a/c came down.
"Having worked in southern and eastern Africa for years, let me tell you that any bigger piece of debris would be re-used. A flaperon makes a perfect piece of roof, seats are, well, seats, etc. [...] What would be needed now is an awareness campaign (together with financial reward) along these coasts."
Yes indeed. A mammoth task, but at least the talk of money spreads fast - even without phones and the internet.
"That the flaperon washed up on Reunion, which is French and therefore rather well organized, was pure and utter luck."
If, as the experts seem to be suggesting, it were the only piece of floating debris from MH370, I would agree emphatically. If there were dozens, it would still rank as remarkably fortunate, IMO.
"I am reasonably certain that there is more debris being washed ashore..."
Assuming the flaperon is from MH370, it seems inevitable - unless the sea was freakishly smooth where the a/c came down.
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gawbc --
I wonder whether a native English speaker with no flying experience would understand "The aircraft rotated at one hundred and sixty knots"?
Well a native French speaker couldn't translate it!
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"dériver entre deux eaux" means "to drift in midwater"... not fully buoyant, not fully sinked, but submerged at some depth ("entre deux eaux" litteraly means "between two water masses" so with a water column above and beneath).
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https://upload.wikimedia.org/wikiped...ocator.svg.png
Strangely, this is an MH370 wiki page showing exactly the thermocline I briefly described earlier.
The thermocline can be thin, and can hold debris.
Strangely, this is an MH370 wiki page showing exactly the thermocline I briefly described earlier.
The thermocline can be thin, and can hold debris.
Last edited by catch21; 24th Aug 2015 at 10:17.