By Victor Iannello
Don’t be fooled by claims of the red tape causing the delay in the determination of the provenance of the flaperon.
Boeing and the NTSB were parties to the investigation when the flaperon was first brought to Toulouse. It is very unlikely that the Spanish subcontractor ADS-SAU did not immediately turn over all documentation when requested by Boeing. The investigators had to know soon after the start of the investigation what the provenance of the part is, whether or not that determination was made public.
I have said before and continue to believe that there was an attempt to delay the release of the results of the investigation in parallel with planting a seed of doubt regarding the provenance of the part. Just look at the series of events this week. First the claim that Spanish vacation schedules have delayed the identification of the part. Then the claim that the identification was not possible. This was followed by the claim that the flaperon was certainly from MH370.
The pattern of leaking contradictory or false information to the media from off-the-record sources continued in full force this week. I believe this is a story in its own right that should be getting a lot of attention. Perhaps when enough journalists are made to look foolish by reporting contradicting statements, their “reputation instincts” will kick in and compel them to dig deeper.
We who are following this incident should demand that more facts be fully disclosed. Technical reports should be released so that we are not parsing statements from a judge-prosecutor to understand the true meaning of what was written. And journalists should not blindly report statements without attribution.
Brian,
What is “G force”? In my understanding G-force is related to gravitation.
Anyhow, what was a reason for ELT to fail in case of AF447? Also, if I am not mistaken, there was no ELT signal in the crash of AirAsia 8501.
Victor,
Re: “It may be that the perps were not trying to avoid Indonesian radar. Rather, they were avoiding Indonesian territory,…”
This depends on where they were heading to and for what.
You must be the first to consider the crash of AF447 “a soft water landing”. The severity of the impact is primarily a determined by the vertical speed. In the case of AF447 the vertical speed was about equal to the horizontal speed: “The last recorded values were a vertical speed of -10,912 ft/min, a ground speed of 107 kt, pitch attitude of 16.2 degrees nose-up, roll angle of 5.3 degrees left”. The aft fuselage hit the water first, exposing the vertical stabilizer and rudder to an acceleration that exceeded 36 g, as evidenced by the failure of a structural element designed to hold the rudder in place against an acceleration of 36 g acting in the direction of the rudder hinge axis.
Gysbreght,
“The aft fuselage hit the water first, exposing the vertical stabilizer and rudder to an acceleration that exceeded 36 g…”
That is what I am saying with regard to the flaperon of MH370. My wild guess is that it would also be torn away at 36 g… For some reason this possibility is not considered by either camp here.
Horizontal control surfaces (e.g. a flaperon) and supporting hinge brackets must be designed for inertia loads acting parallel to the hinge line of 18 times their weight (18 g).
My last post was written before reading oleksandr’s comment. I guess the flaperon was damaged and torn away by hydrodynamic forces rather than inertia loads.
U.S. Agrees to Begin Military Talks With Russia on Syria
http://www.nytimes.com/2015/09/19/world/europe/us-to-begin-military-talks-with-russia-on-syria.html
hope it is path from mutually assured destruction to mutually assured support
Dennis – I don’t anticipate we are going to see any flaperon anaysis any time soon.
@Oleksandr,
G Force … a loose term in this context for the rate of deceleration [along any axis] during a “ditching”, to help decide if the ELT might trigger.
Of course, even if it did trigger there is still no guarantee that there was a successful transmission. If there was significant damage due to the deceleration then the ELT antennae or cables etc may have been damaged too. If there was little damage but the ELTs were under water in less than 50 seconds then any transmission would not have been successful.
My point is that I would expect the ELT to trigger in a controlled water landing [although there is no reference to this in the report on the Hudson landing]. If so, this would seem to discount such a landing in the SIO. The aircraft was significantly damaged, or sank quickly.
I’m well aware of the performance [or non performance] of ELTs in aircraft accidents in general.
Gysbreght,
I was assuming if they (perps) could successfully go dark at IGARI, skirt the FIR boundaries, allude RMAF and the like, then surely they would have to know some satcom knowledge. I fully understand it is the ground station kicking in after an hour of idle time and abnormal during flight, which leads us back again to, did someone reconnect the left AC bus and why. Or is there some way to “deselect” the AES from the FMS and reselect it again? Can the AES be dormant but still logged on to the system?
The conclusions drawn from the Inmarsat data of MH370 do NOT point to a ‘crash’ in the sense of an ‘uncontrolled high speed descent’ into the water. Instead, the data suggests fuel exhaustion, followed by power-up using the RAT.
A similar thing (fuel exhaustion) happened in 2001 in the case of Air Transat F236 , an Airbus A330 of the same size as B777. Both engines flamed out after fuel exhaustion, and the RAT powered up the critical systems between the last engine flameout and final touch-down. But in the case of AT F236, it was glided to a landing in the Azores by conscious pilots.
Crucially, the time lag between the flameout of the last engine, and final touchdown was approximately 20 minutes.
So, the experience of F236, and the Inmarsat data of MH370 both suggest that after the RAT powered-up the critical systems which triggered the SDU log-on, the aircraft would have hit the water about 20 mnts afterwards, at the latest.
After the plane hits the water, there would be no more power to the SDU.
——————————-
If I’m not mistaken, the problem with any route east (I think) is the issue of the InmarSAT pings.
Taking a look at the Inmarsat coverage map, the following becomes evident.
http://www.inmarsat.com/about-us/our-satellites/our-coverage/
The Inmarsat-3 satellites are at geosynchronous orbits over the equator. But significantly, the coverage overlap between F1 in the Indian Ocean and F3 in the Pacific Ocean begins exactly above Malaysia. Now the aircraft’s SDU automatically orients it’s antennae towards the satellite closest to it, based on the aircraft’s current location, and direction. If the MH370 moved east, the Satellite pings would be received at 2 different satellites, thus giving away it’s approximate location at a particular time. Plus, any East-West movement is towards or away from the satellites, and BTO data can quickly provide accurate distance information.
But if the aircraft moved along a North-South arc (approximately) on the earth that is equidistant to ONE satellite (as we now have with MH370) the aircraft becomes harder to locate.
However, thanks to the BFO data, and the wobble of the F3 satellite, Inmarsat was able to overcome this handicap and determine that the aircraft took the Southern direction towards the Indian Ocean.
Significantly, the existence of the BFO data only came to light after MH370 disappeared. If I’m not mistaken, the BTO data could be obtained even after the fact by replicating the scenario. But the precious BFO data is unique to MH370.
CliffG:
Sorry, but you are dead wrong. The Inmarsat data (15,000 ft/min descent rate @ 00:19:37), flaperon photos (TE evidence of high speed flutter) and 777 simulator data (steep turns and 90 degree bank angles) are all consistent with a steep final spiral. The RAT does NOT provide any power to the AES. The AES rebooted after the APU started up.
@Matty
I agree on the flaperon analysis. Very frustrating. It would be very helpful at this point.
@ALSM
Yes, I agree the evidence does support a steep descent. A bogus BFO value due to reboot and hydrodynamic flaperon damage cannot be ruled out, however. The flaperon analytics are extremely important in this regard.
@airlandseaman:
Inmarsat engineers advise to ignore the BFO value recorded at 00:19:37. Even if you believe that this value indicates a high rate of descent at that particular moment, it says nothing about the remainder of the descent. In the transcript of a simulator test you provided, the airplane at 12 minutes after first flameout descended at 12,500 ft/min, recovered all by itself to level flight, then continued the descent at up to 22,500 ft/min. These high rates of descent developed because of the high bankangles that resulted from the mistrim you applied to the rudder, and are in contrast to the low bankangles reported by the ATSB in tests conducted by Boeing and others. All simulator tests assume an unresponsive crew, which is an arbitrary assumption not supported by any evidence.
The damage seen in the flaperon photos is not evidence of “high speed flutter” but of high pressure applied to the underside of the flaperon.
A graph to illustrate the level-off mentioned in my post above:
https://www.dropbox.com/s/cogzenjfg2y52dy/alsm_transcript.jpg?dl=0
@ALSM …I think the ATSB is in a better position to explain this,….here’s the full explanation (p.33):
“SDU POWER UP
Following the loss of AC power on both buses19, the SDU would have experienced a power interruption sufficiently long to force a shut-down, the aircraft’s ram air turbine20 (RAT) would deploy from the fuselage into the aircraft’s slipstream and the APU would auto-start. The APU would take approximately one minute to start-up and come ‘on-line’ after which time it could have provided electrical power21 to the SDU. After power became available, the SDU would take approximately 2 minutes and 40 seconds to reach the log on stage evidenced in the SATCOM log at 0019.29.
If engaged, the autopilot could have remained engaged following the first engine flame-out but would have disengaged after the second engine flamed-out. By the time of the SATCOM log on message, the autopilot would have been disengaged for approximately 3 minutes and 40 seconds. If there were no control inputs then it would be expected that eventually a spiral descent would develop. In the event of control inputs, it is possible that, depending on altitude, the aircraft could glide for 100+ NM.”
http://www.atsb.gov.au/media/5243942/ae-2014-054_mh370_-_definition_of_underwater_search_areas_18aug2014.pdf
BTW: In the case of Air Transat F236 A330, the descent rate after final engine flameout was about 2000 ft/mnt.
@CliffG: Some comments:
1. We are all aware of the language in the ATSB report that you quoted.
2. The RAT does not lead to the power up of the SATCOM. The SATCOM is powered by the APU, not the RAT.
3. The power up of the APU is independent of the RAT. When the APU senses that both busses are down, it automatically starts using its own batteries.
4. This is deja vu all over again.
Victor: On target as usual.
CliffG: Everything I have written on this subject is (or was meant to be) 100% consistent with the ATSB report language you quoted. Absent pilot inputs, “…it would be expected that eventually a spiral descent would develop…”
Gysbreght: I’m sure you are well aware that subsequent to the ATSB advice you reference, ATSB acknowledged that the final BFO values might in fact indicate a rapid descent. The statement you quote is misleading at best. It was an early assessment, predating the time when vertical descent rate was incorporated into the ATSB model. Victor was the first independent researcher to bring this up, and after ATSB picked up on the importance of the “discovery”, they came around to agree that the final BFO values were quite possibly accurate, or at least highly indicative of a steep descent at 00:19:37. They could be off ±100 Hz and the descent rate would still be in the range of 10,000 to 20,000 ft/minute. There is absolutely no way the BFO values could be in error more than ±100 Hz.
No I’m not aware of that at all. In their June report the the ATSB wrote “eventually a spiral descent would develop…” and in the October Update they wrote: “a descending spiralling low bank angle left turn”. They never said anything about encountering nearly inverted bank or supersonic speeds.
The Inmarsat authors of the Journal of Navigation article wrote about the BFO value:
Gysbreght:
Even the 00:19:29 BFO measurement, which you apparently believe in, indicated a descent rate of 4800 ft/min.
Regarding the ADSB caution about the second logon BFO value: It should be noted that the initial BFO Bias error at the 3 logins occurring at 1600, 1825 and 0019 were caused by different conditions. At 1600, the power had been on for 4 hours continuously, and the initial error was ~17 Hz. At 1825, the OCXO power had been off for about an hour, meaning the OCXO was probably still coming to thermal equilibrium, thus a valid ATSB caution. At 0019, the OCXO power had only been off for about a minute, and thus it would have been very close to equilibrium before the power came back on, and certainly not in error by >100 Hz 3 minutes later. The 0019 second packet BFO error was probably much closer to the 1600 case than the 1825 case.
airlandseaman:
I’m aware of that. There are many situations and maneuvers, piloted or unpiloted, compatible with that momentary descent rate. What about it?
You should not attribute to the ATSB what Inmarsat’s engineers have written in an article in the Journal of Navigation. The rest is your judgment, apparently not shared by the Inmarsat specialists.
Anyway, the fact that nothing has been found near the 7th arc sofar is a strong indication that the “unresponsive crew” theory, and your spiral dive theory, should be discarded.
@VictorI
You are incorrect in how the APU functions. According to the ATSB report, “The APU is supplied with fuel from the same tank as the left engine. Operation of the APU, after the left engine flamed-out, would be unreliable and would be of short duration before it too flamed-out.”
.. but thanks for pointing out that the APU powers the SDU, not the RAT. However, both the APU and the RAT start up at about the same time.
… interestingly, if the second log-on was triggered by the APU and the APU failed shortly thereafter, it means the SDU would have been non-functional BEFORE the aircraft hit the water.
Or am I missing something here?
_____________
BTW: The descent rate of Air Transat F236 was 2000ft/mnt. If MH370 was descending from about the same altitude, that descent rate should be within safe limits for a controlled ditching on the ocean.
@CliffG: Again, we are well-aware of what is written in the ATSB report, and I have not written anything that is inconsistent, despite your claim that somehow I am incorrect.
The APU is believed to have lit off using the remaining fuel in its fuel line after the start sequence was started by battery. The operation of the APU did not last long, hence the incomplete handshake sequence. This flameout of the APU is believed to have occurred before hitting the water.
Victor, Mike, CliffG,
Power system is described in FI, though the description is a bit fuzzy (actually thanks to Mike, who pointed on FI). I strongly disagree with Victor’s “This is deja vu all over again” – on contrary, I think something interesting can be squeezed from it.
Please correct me if I am wrong:
1. IDGs provide power to the right and left buses as a normal operation.
2. APU functions in parallel to IDGs. It may supply additional power of 120 KVA as needed, or if one of the buses de-powered, or if both buses de-powered (p.28 of FI). Moreover, it appears that if one of the buses de-powered (such as in case of the flameout), APU would kick in (if not operating) and supply the power to the respective bus. APU relies on a gas turbine generator.
3. If both IDGs and APU are not operational, backup generators are activated. Interestingly, FI says “To reduce electrical loading on the backup generator, the following systems are inoperative: TCAS, SATCOM, Right HF radio” (p.10).
4. If all of the above is not working, batteries and RAT (so called “standby electrical system”) provide power to critical flight instruments, communication and navigation systems (p.11).
@Oleksandr
“I should also note that “ridiculous hijack” and “bizarre mechanical failures” are the only two scenarios, which pass both the logic and data tests. The other scenarios do not pass. Including CI. CI hypothesis does not have a plausible motive, does it?”
what is it exactly that you don’t find plausible? Pilot diverting airplane to another country happened only two weeks before MH370, CI was the goal of hijack flight some 20 years ago (that one also didn’t succeed).
So, nothing unprecedented.
“Re: “It may be that the perps were not trying to avoid Indonesian radar. Rather, they were avoiding Indonesian territory,…”
This depends on where they were heading to and for what.”
if they intentionally went around Indonesia to turn SE(and they most likely did) then CI (or Cocos) was the only plausible location to get to (ditching a civilian airliner to get into a boat is something that most brave commandos and pilots wouldn’t even try, high chance of failure)
Gsbreght,
“They never said anything about encountering nearly inverted bank or supersonic speeds.”
Who is claiming nearly inverted bank and supersonic speeds?
Not the IG. The words used by the ATSB are entirely consistent with the IG statements. In fact a descent rate of 15,000 ft/min means that the trajectory of the aircraft, at say 500 knots, is only about 17 degrees below the horizon. A low bank angle is consistent with this too. Hence… spiral dive. Of course if this attitude was maintained, one would expect the speed to increase too.
Please stop the exaggerations and the unwarranted criticisms.
Oleksandr,
“3. If both IDGs and APU are not operational, backup generators are activated”
What backup generators? With both engines out ?
CliffG,
” that descent rate (2000ft/min) should be within safe limits for a controlled ditching on the ocean.”
Please read the NTSB report of the investigation into the Hudson ditching. That was controlled, but at a calculated rate of 750 ft/min, considerably greater than the certified 210 ft/min. Significant damage occurred. A descent rate into water at 2000 ft/min would result in catastrophic damage.
StevanG,
Several times I posted a batch of questions “against” CI, and only the last time Dennis commented some of them. Ok [deep breath], one by one. Depending on your answers I will ask you next question(s). Please refrain from “maybe” just to complete a single solid CI scenario – these “maybe” often make things incompatible with each other. You will see that such a scenario will combine signs of being ridiculous and bizzare.
1. What is motive?
Brian,
FI says that there are two backup permanent magnet generators (PMGs), installed at each of the engines (p. 10). FI does not detail on how these function.
I considered both the log-on events. Are you saying that the first log-on event 18:25 was also due to engines out? If yes, then aircraft would not be able to maintain its FL. If no, than considering sufficient means to insure uninterrupted power, why such a mess in BTO & BFO 18:25-18:27?
Mike,
Re: “There is absolutely no way the BFO values could be in error more than ±100 Hz”.
What do you mean? I though previously we were talking about 5 Hz or so in the measurements (i.e. except external factors affecting BFO). And why 100 Hz?
@oleksandr
The motive for the CI scenario is simply a political statement. The island is a refuge for Chinese Nationals in any case. Shah never intended to harm anyone. He was simply disgusted with life as usual in Malaysia.
The CI scenario fits:
1) the ISAT data
2) plausible motive
3) drift models
4) sea anomaly data
It is as solid as a rock, and gets more solid as time passes.
There is nothing to support the current search area but a spreadsheet. The aircraft is nowhere near that area. I am quite sure of that. It is a classic example of the talking dog effect. The IG, ATSB, and various others such as Cole and Ullich simply have their heads up their butts.
Gysbreght,
Re: “I guess the flaperon was damaged and torn away by hydrodynamic forces rather than inertia loads”.
What does make you think so?
Well, in the posted transcription of one of the tests, the bank angle reached 85 degrees and the speed came close to Mach=1.
That limit is Mdf=0.96 .
That is all very different from what the ATSB describes in two reports.
Well, in the posted transcription of one of the tests, the bank angle reached 85 degrees and the speed came close to Mach=1.
The speed increased so much because the bank angle went to 85 degrees and nobody pulled the nose up to generate the corresponding ‘g’. At low bank angle the airplane would not have accelerated as it did in that simulation.
Dennis,
Divide and conquer… Let drift models and ISAT data rest for a while.
2. What benefits of making political statement upon arrival rather than more dramatic statement in the air? How could he be sure that he would be allowed to make a statement at all (this depends on the current political interests of Australia/CI authorities)? For comparison, the hijacker of Ethiopian Flight 702 was 31-yeal old, and he was jailed for 19 years and 6 month. Shah has a lot of things to loose: Malaysia is not Ethiopia. And Shah was a relatively old and rather successful man. Not all Australians can afford 2 houses and 3 cars.
3. Why did he need to hide from radars and avoid Indonesian airspace if the purpose was to make a public statement? What harm could interceptors do to him? As long as they knew that this B777 did not pose any threat, and has nothing to do with their country, Indonesians would prefer to escort and let it go.
4. Same about Thailand (I mean flight over Langkawi vs Penang, which is shorter). If I recall correctly, you explained this by inaccurate radar data.
5. Why SDU off/on? What did he achieve by this game?
6. Why there was no SOS from the cabin? I know Don did not comment, but my impression is that FI is certain that it was possible.
7. We saw a piece – if it was Shah, he did not succeed in landing. Why? And why would he wait till the fuel exhaustion?
Oleksandr/Dennis – Interesting set-up this. Hard and fast crunchers will say it’s down there in the search area because the data says that, others might say the search area is the one place we know it isn’t – or we are very close to concluding such. Or if it’s there we missed it – every bit of it? Worth factoring in that there was no fire with this crash so no smoking hole and everything is dispersed from top to bottom. If a flaperon went to Reunion where did 400 MAS life jackets go? You could argue there is some ambiguity with the state of the flaperon but in totality, the absence of debris alongside it could suggest a ditch. The only bit of plane we have is the kind of bit that would be torn away in such an event.
If it’s near CI I would prefer to think it’s incidental.
Gysbreght,
Once again you are taking small pieces of information out of context, and then embellishing them with your own opinion.
Please refer to what the IG wrote. Nothing about near vertical, or almost inverted, or supersonic speeds. Yes, the sim tests show a variety of flight attitudes that could possibly occur, but none are inconsistent with the IG position of a “spiral dive” having occurred, and this is not inconsistent with the ATSB’s views either.
@Matty Amen
@falken
Your passion and sincerity is always appreciated, thank you.
The RADAR has always been suspect to me. As an alternative as we have time, what end of flight scenarios can be calculated if it was excluded.
It is quite puzzling as to why someone would suggest that MH370 entered into an uncontrolled descent when it is equipped with modern wings that enable it glide efficiently, and fly-by-wire technology that enables the pilot to control the glide with minimal input. The pilot could have ditched the aircraft in one piece in the sea without too much trouble.
Modern jet airliners have “long, thin, sophisticated wings meant to lift well at high altitude, with minimal drag, and to milk the maximum range from the fuel aboard. ….Modern airliners have become good gliders in their own right, [and]…during routine descents …the engines are throttled back to a minimum setting known as “flight idle,” at which they produce hardly any thrust at all, and,…the airplanes are glided for as much as 50 miles until arriving at the desired lower altitudes, where power is again applied.”
http://www.vanityfair.com/culture/2009/06/us_airways200906
“The fly-by-wire system also incorporates flight envelope protection, a system that guides pilot inputs within a computer-calculated framework of operating parameters, acting to prevent stalls, overspeeds, and excessively stressful maneuvers.” (Wikipedia)
If the intention was to ditch the aircraft in one piece with minimal debris, choosing a B777 would be the right choice.
@CliffG
Your extensive research, time and effort is apparent yet your intentions are not. Do you have a theory of what occurred or are you simply a “devil’s advocate”? Your posts are substantially informative yet inconclusive of your theory which respectfully keeps the playing field level
Asylum at Christmas island
http://www.theguardian.com/australia-news/2014/oct/13/-sp-segregation-isolation-death-christmas-island-the-hellish-paradise-asylum-seekers-call-home
I cannot imagine that Shah would look for Asylum on such a location and under such conditions, when he had the half of the world as destinations available.
And he would have been lucky to end in the CI detention center arriving with an aircraft full of hostages instead in a prison awaiting his forcefull repatriation to Malaysia.
@CliffG
Your description fits a modern FBW aircraft with all systems and protections working.
What we are discussing are two versions (with some subversions) of end of flight scenario.
The Boeing and others simulator tests assumed the out of fuel version without a pilot, where limited hydraulic and electrical power would degrade the normal aircraft operating specs considerably, especially the named flight envelope protections. A crash is the most reasonable result under such conditions, where extreme speeds, bank angles and descent rates could be present. With a pilot on the controls after fuel exhaustion a ditch would be possible, but with the degraded aircraft systems such a ditch could still end in a crash with a high probability.
Attempting a ditch prior fuel exhaustion with a fully functional aircraft would be the a more reasonable decision with a higher probability of success.
We discuss this in view of the found flaperon.
In the no fuel no pilot end scenario the flaps would be up and if the flaperon departed the aurcraft at contact with the sea, so would other parts have as well.
In the other piloted end of flight scenarios ( prior or after fuel exhaustion) the pilot would configure the aircraft to minimize the touchdown speed as far as possible, hence full flaps. The flaperons extend considerably less downward compared to the leading and trailing edge flaps. It seems fair to assume, that the trailing edge flaps would have departed together with the flaperon and other parts if the wings.
In the end without detailed analysis not available to us the flaperon, if we believe the published findings of the French, only tells us that it once had been mounted to 9M-MRO.
With all due respect, this is getting silly. Why should I refer to something somebody else wrote on some other blog? How can bank angles near 90 degrees be “not inconsistent” with the ATSB’s “low bank angle”?
As to “taking small pieces of information out of context”, all my quotes are given with name, date and time, so anybody needing more “context” can easily find it.
You’re jumping in on a discussion I was having with with some other contributor to this blog. Let’s stop this silly exchange here.
Gysbreght,
Well, there you go again. Bank angles near 90 deg were observed, but the IG statements referred to a “spiral dive”. It is the spiral dive that is not inconsistent with the ATSBs “low bank angle”.
Oh, excuse me for jumping in on the discussion you were having with someone else. Was it private ?
I’m happy to stop the exchange, since it is apparent that you have nothing of substance to add, and prefer to continue to criticise and distort the work and opinions of others without contributing any useful analysis of your own.
My last word. I’ve got better things to do.
#Susie thank you too; everybody here helps to solve the puzzle; my hopes and fears
A little sidestep into performance, aerodynamics and flight dynamics.
The descent table in the FCOM (page PI.21.6) states that a normal descent from FL350 takes 124 NM and 23 minutes. That equates to an average rate of descent of 1522 ft/min and a glide ratio of 21.5 .
In ALSM’s simulator test shown in the ‘transcription’, the airplane descended at approximately constant 200 kIAS and 2000 ft/min in the first 5.5 minutes after the second engine flame-out, i.e. a glide ratio of 12.5 . (Bank angle and rate of turn were nearly constant at 35 degrees and 1.8 degrees/second, respectively).
How can the rather poor performance in the simulator test be explained? Part of the difference is obviously caused by the engines. In a normal descent the engines are at flight idle thrust, which is typically slightly negative at flight speeds but generally close to zero. With two engines flamed out there will be windmilling drag, so the glide ratio will be somewhat less than in a normal descent. The ATSB estimates that the airplane could have travelled about 100+ NM, and from FL350 that would correspond to a glide ratio of 17.4 or more.
ALSM writes that all cases tested resulted in turns starting shortly after the second engine flamed out. Indeed in the transcription we see the heading change starting immediately after 2nd engine flame-out. If we want to consider why turns started, then “starting shortly after” is not an adequate description. Normal ‘coördinated’ turns are initiated with the ailerons, and as the airplane gets banked, it starts to turn (change heading).
In the simulations there was no control input, the turn started because the A/P disconnected and the airplane was not in trim. An airplane can be out of trim laterally (ailerons) and directionally (rudder). In the case documented in the transcription we know that the airplane was directionally out of trim because the rudder trim was set to 1 degree NOSE R. Application of rudder causes the airplane initially to yaw into a sideslip. The sideslip results in a rolling moment causing the airplane to bank, then the flight path starts changing direction.
However, sideslip also increases the drag, and I think that the drag due to sideslip is the reason for the poor performance observed in the simulation.
Of course, Airlandseaman or Brian Anderson can prove me wrong with the more detailed data they have access to.
@Gysbreght
Let’s think logical, please.
Both engines running we have an aircraft in trim and with autopilot on and all flight envelope protections working.
Failure of the first engine will cause an out of trim situation due to less thrust on the dead engine and increased thrust of the good engine to compensate for thrust loss. This mistrim will be corrected by autotrim of the autopilot and FBW system.
Failure of the second engine will cause loss of autopilot, loss of envelope protection and loss of autotrim in due course. The loss of thrust on the second engine therefore may leave the aircraft in considerable out of trim condition.
But I may be wrong though.
@RetiredF4:
“But I may be wrong though.” Yes, you are. Read Airlandseaman’s description of the TAC function.