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.
@Hudson:
” I suspect the flight attendants knew immediately at IGARI that something was very wrong.”
Why that suspicion? The flight attendants were busy persuing their normal duties, serving drinks and meals, distributing blankets, etc. If anything, they would be in a worse position than the seated passengers to detect a slight increase (10%) of g-level. What difference does it make if anybody in the cabin was aware of something unusual?
G’day again folks. If I can contribute a couple of thoughts/answers…..
Flitzer_Flyer:
Posted September 24, 2015 at 1:01 AM
“Does the lack of ELT transmissions provide any clues, or eliminate some possibilities?”
Flitzer, I have read somewhere ELT’s in regards to aircraft accidents have had an 80% failure rate to date, maybe it was even on this site. Not good odds at all. I can not provide a link to back this up, but if so interested, I’m sure you could find something on the failure rate of aircraft ELT’s.
****************************************
Brock McEwen:
Posted September 24, 2015 at 6:45 PM
“@Matty, @MuOne, and/or any other Aussie in the forum: might I have a chance at cajoling one of you into making what the Yanks would call a “Freedom Of Information Act” (FOIA) request? I presume you have some rough equivalent down under.”
Hi Brock. FOI…LMAO. Its only free if they want you to see it, otherwise some technicality will see it knocked back. See here: oaic dot gov dot au/freedom-of-information/foi-resources/all/ (adding the usual protocol before hand). I would think non residents can make applications if required?????
********************************************
Cheryl:
Posted September 24, 2015 at 9:38 PM
“Unless some were awake and on their own tablet devices, which would greatly depend on MAS rules and Wi-Fi inflight capabilities, then they would not have seen the change of direction on the moving map on the IFE unless having seen it on their tablets? Did MAS provide inflight Wi-Fi or whatever technical power is needed to use such tablets?”
G’day Cheryl. You probably forgot this point I made previously (not surprising considering the sheer volume of stuff discussed here for so long now). No need for the airplane or any external data source is required for moving map. Just moving map software on the tab and its own internal gps. I have watched in real time and recorded track logs of a few journeys now, all without the assistance of the airline.
*******************************************
Matty – Perth:
Posted September 25, 2015 at 3:05 AM
“American aeronautical engineers dispute this, pointing out that as is the case with the MQ-1 Predator, the MQ-9 Reaper, and the Tomahawk, “GPS is not the primary navigation sensor for the RQ-170… The vehicle gets its flight path orders from an inertial navigation system”.[20] Inertial navigation continues to be used on military aircraft despite the advent of GPS because GPS signal jamming and spoofing are relatively simple operations.”
Matty, INS requires frequent GPS input for calibration of the gyro’s. So whilst the INS maybe the sole navigation system, it still requires some calibration input. Maybe the drones get fed this information via encrypted data sources. Even so, hacking/spoofing of this encrypted data is potentially an avenue to divert a drone (albeit a highly unlikely one). However the precedent has apparently been set, so its proven to be doable, however the method.
@Sharkcaver,
“ELT’s in regards to aircraft accidents have had an 80% failure rate”
Yes, I understand that. There are references in the ATSB FI, the FAA website, and elsewhere. The point is that the ELT itself did not fail. It is the lack of transmissions that is the problem.
And this is exactly my point. Why were there no transmissions in this case?
– because the ELTs/cables/antennae were damaged in a crash, or,
– because the ELTs were under water in less than 50 seconds
– cabin crew unable to activate
– flight crew significantly distracted, or unable to activate manually.
If these are reasonable reasons, then a number of the “conspiracy” theories might be eliminated, as can any possibility of a soft “controlled” ditch.
@Gysbrecht
“What difference does it make if anybody in the cabin was aware of something unusual?”
The difference would be in the interpretation of events, whether significant or not is probably not determinable at this point.
Does the available data suggest that there were NOT significant altitude changes to cause depressurization or is it inconclusive?
@Susie Crowe:
AFAIK the available data do not suggest that there were significant altitude changes. Altitude changes do not cause depressurization, except when the maximum permitted altitude is exceeded significantly, but even then pressure changes within the cabin would be slow and small.
Gysbreght,
Thank you for continuing to pursue the PFCS operation & the consequences of RAT power. My post wasn’t a guess, rather extrapolating the consequence of running on RAT for an extended period.
With only the RAT providing standby electrical power & pressurizing the Center hydraulics system the PFCS has lost its ability to sense input conditions (e.g. air data probes without heating) and lost its ability to fully control all the flight surfaces. PFCS primary mode is definitely untenable and the AMM states, “The PFCS selects the direct mode when there are failures that make the normal and secondary modes unreliable“. However, I’ve yet to see a specific list of those failures.
During one recording of ALSM’s simulator flight trials the EICAS message “FLIGHT CONTROL MODE”, indicating PFCS secondary mode, was clearly discernable after both engines and the APU had flamed out, and the RAT was online. I couldn’t discern all EICAS messages generated throughout the recorded clip so can’t confirm if “PRI FLIGHT COMPUTERS”, direct mode, was later displayed.
The RAT hydraulic pump powers only the Center hydraulic system, the L & R systems will eventually depressurize & become ineffective, I’d be interested to understand how quickly that occurs. The horiztl stab jackscrew hyd motors require a significant thruflow. Without the Left and Right hydraulic systems pressurized two flight control surfaces (LH flaperon & RH elevator not powered by Ctr system) are inoperative. The ACE detects hydraulic pressure conditions from the PCUs in order to set the PCU’s bypass valves & those low pressure conditions are monitored by the ACE units in the PFCS.
Oleksandr,
RAT deployment is simultaneous with the APU start.
Concerning the AES and datalink activity after 00:19 – the AES completed the GES Log On. GES Log On is the only action the AES intiates independently of other connected systems on the aircraft. The AES then signals other systems that the datalink is ready and they initiate their virtual circuits, via the AES, over the datalink: 1) ACARS Mgr initiates a VC to SITA’s ACARS processor (didn’t occur at 18:25, I don’t believe it should be expected at 00:19); 2) IFE comms manager initiates a VC to OnAir’s IFE Messaging processor (did occur at 18:25). Boot timing for the IFE comms mgr component isn’t published, open question: could the component have completed its boot process & attempted to initiate its VC before the APU flamed out and Main AC bus power was lost again.
:Don
@Gysbreght
Thank you for your patience. Would hypoxia then, be considered unreasonable?
@ Guarded Don
Thank you for your detailed post on the available systems when both engines are inoperative and the jet has to work with what is left.
One important bit is unclear though.
“Without the Left and Right hydraulic systems pressurized two flight control surfaces (LH flaperon & RH elevator not powered by Ctr system) are inoperative”.
Could you please confirm, if that is correct? That would result in an assymetric flight control response in direct mode or an assymetric flap down condition if the LH flaperon would work neither as aileron nor as flap while the RH flaperon would work like advertised. Especially when working with downgraded systems you do not want aditional avoidable handicaps. I thought I have read somewhere that the secondary flight controls, which include the flaperons, do not work in direct mode, which would make sense.
This is especially important as the trailing edge damage to the La Reunion flaperon is, besides flutter damage, considered to be from a controlled ditching event. But with the flaperons inoperative they would be near flush with the wing, while the flaps in such a controlled ditching would be extended and thus be more perceptible for damage and detachement from the wing than the flaperon.
Gysbreght,
“AFAIK the available data do not suggest that there were significant altitude changes”
I hope you are not infected by N571. Radar data show changes and gaps, but considered inaccurate. It is not certain whether gap near MEKAR and disappearance 18:22 is caused by the change in altitude, or due to the mountainous terrain. Speed variations during 17:22-18:22 still allow the aircraft to drop to 7 km altitude or so without significant implications on its ability to reach MEKAR. Fuel-implications could still be consistent with other locations at the 7th arc (see ATSB fuel endurance curve). And nothing is really known about the altitude after 18:22.
Equally, the available data do not suggest that flight level was constant or nearly constant.
——–
Susie,
“The difference would be in the interpretation of events”.
What events and what interpretations? Say, if passengers knew that something was wrong by 17:22, 18:00 or 18:27, what does this change?
Don,
Thank you for this correction and further information. During 18:25 logon, the next transaction occurred in 88.5 seconds. Can MCDU also trigger transaction besides ACARS and IFE?
Either way, it appears from FI that it was IFE for the case 18:25-18:27 (some data associated with IFE was apparently received 18:27). This means IFE was also rebooted. If it was because of the power, then APU would start 18:22. Something weird was going on, or we do not correctly interpret the sequence of events.
Don,
Does MCDU have to transmit any data upon a successful AES log-in and/or MCDU boot-up?
JS/RetiredF4 – we are obviously speculating with the idea of electronically diverting rogue jets but if it was real it would be well out of view until the day it was required. It wouldn’t go anywhere near the ambit of civil aviation. More like missile defense.
@Oleksandr
Being mindful not to waste someone’s time and knowledge I’ve carefully considered that question. Is there insignificance of anything that happened on that flight? Sadly, nothing can be changed about what happened that day, trying to ascertain what the passengers and crew witnessed is most certainly what the nok would want to know
Oleksandr,
It is correct according to the 4 Corners piece. It specifically states that the IFE was interfered with at the same time as the loss of the other comms but does not explain how. If there was no connectivity with the satellite or handshakes between 17:21 and 18:25 wouldn’t that suggest that the satcom link (AES) was compromised in some way, disabled, jammed or malfunctioned at that time? Therefore no satcom link, no IFE (and no Airshow plating on said IFE) since it depends on one?
Sharkcaver,
Thank you for clarifying the tablet usage during flight. Yes I did forget that point.
Oleksandr,
It is correct according to the 4 Corners piece. It specifically states that the IFE was interfered with at the same time as the loss of the other comms but does not explain how. If there was no connectivity with the satellite or handshakes between 17:21 and 18:25 wouldn’t that suggest that the satcom link (AES) was compromised in some way, disabled, jammed or malfunctioned at that time? Therefore no satcom link, no IFE (and no Airshow playing on said IFE) since it depends on that link?
Sharkcaver,
Thank you for clarifying the tablet usage during flight. Yes I did forget that point.
Oleksandr,
Somehow I missed your post of Sept. 7, which linked to a ‘Technical Note on possible “Constant thrust settings” flight trajectory of MH370’.
Interesting analysis, I am slowly working through it. In Equation (1), you write: d(mu)/dt = …, etc. I think the left side of this equation should instead be of the form: m d(u)/dt = …., etc. The right side of the equation only includes changes in momentum due to forces, not momentum loss due to mass flows (e.g., burning and/or dumping of fuel.)
ELTs in the cabin
According to Boeing documentation, there should be several hand-operated ELTs in the cabin. If the flight attendants and passengers became aware that something is seriously wrong, this may not be the first thing they would do, but eventually someone would probably try to activate one. So this argues that everyone was incapacitated early on.
@Sharkcaver: thanks for the link. Yes, I’ll try it myself, if no residency requirement/advantage.
@Gysbreght
> Do they ever leave the autopilot unattended on a constant heading for many hours? Of course not.
Ever? No. Unattended? No. However, these qualifiers are a bit misleading I dare say.
It is possible that Zaharie or Hamid or whoever did in fact do just this. MH370 was anything but typical. Although most likely the cockpit was not unattended, the possibility that AP was engaged on a constant heading absent further control inputs until near fuel exhaustion is certainly plausible, if not likely.
Of course, with Mike Exner’s excellent flaperon analysis, we can all but rule this out. I’m assuming that Mr. Exner (along with the others) has the requisite skill set to make the ‘flutter separation in-flight’ determination. I would certainly hope so, at least.
Curious though that this level of confidence exhibited by Mr. Exner was reached so hastily. That he didn’t wait for the BEA and experts to opine suggests to me that he is virtually without doubt. Well and good.
Oleksandr,
In your query of the 18:25 – 18:27 IFE response, isn’t it doing exactly what it was designed to do, respond and come online “90 seconds” after AES or satcom as it is set up independently to do just that was what I found after researching how it operates a year ago? Wasn’t the IFE timing right on point at that point?
Also, if the last ACARS message was at 17:07 something and next expected ACARS message at 17:37 something, and comms went off circa 17:21, I think we can safely assume that the funky occurrence to the AES or satcom was between 17:07 and 17:37, more likely in my opinion between 17:21 and 17:37.
Now as far as the 4 Corners interpretation of “interference” with the IFE circa 17:21 follow me on this if you would please:
From the Factual Information, 1.9.5.3 Satcom Ground Station Logs of Event – Summary (Pg 53)
1. Prior to take-off, the Satcom logged on (normally) a number of times, the last time being 16:00, when it sent a valid Flight ID to the GES….etc.
4. When the Satcom link was re-established at the above times (they are referring to 18:25 UTC and 00:19 UTC) no Flight ID was present.
6. There is no indication of the Satcom link being manually logged off from the cockpit (via an MCDU). Such activity would have been captured in the GES logs, but it was not.
What I interpret this to mean is that possibly the AES was never logged off since it had already given the electronic Flight ID, but in some kind of a technical funk, or as Victor puts it so much better technically than I do, jammed. So am I taking this correctly that whatever this “interference” 4 Corners is referring to it wasn’t pilot related via the FMS or whatever they use to control the AES, but whether it was pilot AC bus/EEbay related we don’t know yet, some glitch, or some kind of system hacking? I would think that regardless of where the IFE is getting it’s GPS information from ADIRU or wherever, it’s not playing if the AES is not operating.
And ironically enough, there was an ongoing Airshow (IFE) related problem on 9M-MR0 per the Factual Information, where there was a problem with the “time to destination.” Whether or not that was still deferred or resolved at the time of flight of MH370 I am not sure.
Apologies in advance if this is a little long. I’ve tried to cut it down as much as possible but wanted to reply to a few posters, and Jeff himself:
****************************************************************
@Jay:
Thank you for the kind words, and yes, you are absolutely right. The major unknown to this ‘theory’ is the presence (or not) of any mechanism/system in place that would allow such an aircraft to be controlled remotely. On the other hand, if something like that existed, events have unfolded exactly as the ‘diverters’ (American/Malaysian military, lets assume) would have wished. A plane at the bottom of the deep, wide ocean, far away, in one piece, nobody any the wiser as to where it went, only a lone flaperon washing ashore after 15 months.
RetiredF4 suggested such a capability would instead be used as a deterrent. But broadcasting it to everyone has one major drawback – it could be an open invitation to terrorists to attempt a hack of their own. With no cost or effort, terrorists would find ready-made ‘weapons’ in the skies. All the more reason to keep things under wraps.
****************************************************************
@Jeff:
Yes, you are absolutely right. That first hour without satellite communication is a massive problem for this theory. That would absolutely point towards a spoof. Unless a capability or mechanism exists/has been rolled out in Boeings which we just don’t know about. But agreed, the latter is in the realms of pure speculation.
****************************************************************
@RetiredF4:
As you rightly say, remote control capability is an unsubstantiated assumption at best, and unprovable. And the point you raise about the how militaries behave in peacetime is also extremely insightful (for me and I’m sure many others here). If the Malaysian military hadn’t been informed until MEKAR, then yes, that contradicts my assumption of ‘very early knowledge.’ But it only dents the theory. The Malaysians would simply have informed the Americans much later, awkward as any such conversation would be.
One thing I disagree with, I don’t think it’s as impossible to hide such an operation as you suggest. The people needed to execute it wouldn’t be in the hundreds and thousands, only a relatively small group of trusted and pre-trained experts and engineers would be required. Likewise, only a select group of senior Chinese and Malaysian military men would really need to know. This was a fast-moving event; the Americans would’ve been running short on time, even more so due to the slackness of Malaysian ATC (as you touched upon). It would be impossible to gain clearance with every single national and multinational agency in existence. The Chinese and Malaysians surely would’ve appreciated that fact. There is always that unknown of potential whistle-blowers, but in such a case, a ‘leak’ would be so destructive for any nation involved that it would almost be an act of military buffoonery if a top-level employee spilled the beans.
But again, all of what I say is pure speculation.
****************************************************************
@Cheryl:
It’s a good point. But if it was a defensive measure someone wanted to keep secret, it would make infinitely more sense to push the plane as far out to sea as was possible (until fuel exhaustion) rather than let it ditch after just 4-5 hours. The genius of pushing it far out to sea is that it resolves many potential problems: the further out it sinks, the less chance of it ever being found (and the lid being blown on the whole operation), the longer it would take any potential debris to wash ashore, the more likely that fuel exhaustion leaves no tell-tale oil slick, the easier it is to keep anything you wanted to remain secret, hidden. (In fact, exactly as events have so far happened)!
****************************************************************
@falken:
I appreciate it does appear that way. But hacking the plane to push it out to sea followed by a cover-up does not necessarily have to be something sinister. Especially if the diversion was to avert a potential terrorist strike, and the cover-up simply to avoid political blowback while keeping the possibility of remotely controlling planes secret.
****************************************************************
@JS @Matty Perth:
If something like this was fitted, you’re absolutely spot on, it would probably be extremely crude – at most allowing the plane to fly in a straight line until fuel exhaustion but incapable of complex turns or landings.
The way I see it, there are only two possibilities. One, the data set is all correct, interpreted relatively accurately, and something prevented the hijacked plane from going any further at IGREX by forcing it deep into the SIO (as you both touched upon).
Or, as Jeff suggests, the IGREX-SIO data is spoofed and there was no southern journey (the plane simply carrying on to where the hijackers wanted).
But either way, we’d be looking at two different separate but linked events from BITOD to IGREX, and IGREX to SIO.
Thank you for doing that extensive research in the AMM and on the videotapes and for sharing what you found.
Isn’t “extrapolating” a form of guessing? I understand that:
– the AMM does not unequivocally say that the FCS will revert to direct mode when the RAT is the only power source
– it was not possible to discern the PRI message on the recorded video clips, nor was it seen by any of the observers in the simulator cab.
The pilot can depressurize the airplane by commanding the outflow valve to OPEN. With the outflow valve open the pressure in the cabin would then remain equal to the ambient pressure, i.e. it would reduce when the airplane climbs.
I thought that ailerons always deflect asymmetrically. Also it seems that the ACEs are quite ‘knowledgeable’ and would probably ‘know’ which PCUs are powered or not. They also have to diffferentiate between the flap function and the aileron function of the flaperons.
According to the FI, none of the ELTs on board transmitted on 406 MHz, the only frequency received by the Cospas-Sarsat satellites.
Quite.
Quite. The “flutter theory” rests on the “high speed dive theory”. The theory of a high speed, near-vertical spiral dive was postulated in the IG’s Progress Report of September 2014, before Mr. Exner’s simulator exercise and the beaching of the flaperon. It has remained an IG canon ever since.
@Sajid UK “keeping the possibility of remotely controlling planes secret” – it seems, mission impossible
@ Gysbreght
“I thought that ailerons always deflect asymmetrically. ”
I should have been preciser in my comment. The roll response to an udentical control input would be different when rolling to the keft or to the right.
“Also it seems that the ACEs are quite ‘knowledgeable’ and would probably ‘know’ which PCUs are powered or not. They also have to diffferentiate between the flap function and the aileron function of the flaperons.”
There are four ACEs and three PFCs employed in the system. The function of the ACE is to interface with the pilot control transducers and to control the Primary Flight Control System actuation with analog servo loops. The role of the PFC is the calculation of control laws by converting the pilot control position into actuation commands, which are then transmitted to the ACE. The PFC also contains ancillary functions, such as system monitoring, crew annunciation, and all the Primary Flight Control System onboard maintenance capabilities.
The ACEs convert the transducer position into a digital value and then transmit that value over the ARINC 629 data busses for use by the PFCs. There are three PFCs in the system, referred to as L, C, and R. The PFCs use these pilot control and surface positions to calculate the required surface commands. At this time, the command of the automatic functions, such as the yaw damper rudder commands, are summed with the flight deck control com- mands, and are then transmitted back to the ACEs via the same ARINC 629 data busses. The ACEs then convert these commands into analog commands for each individual actuator.
Here is a review of the B777 flight control system.
The 777 FBW Primary Flight Control System has three operating modes: Normal, Secondary, and Direct. These modes are defined below:
Normal—In the ‘‘Normal” mode, the PFCs supply actuator position commands to the ACEs, which convert them into an analog servo command. Full functionality is provided, including all enhanced performance, envelope protection, and ride quality features.
Secondary—In the ‘‘Secondary” mode, the PFCs supply actuator position commands to the ACEs, just as in the ‘‘Normal” mode. However, functionality of the system is reduced. For example, the envelope protection functions are not active in the “Secondary” mode. The PFCs enter this mode automatically from the ‘‘Normal” mode when there are sufficient failures in the system or inter- facing systems such that the ‘‘Normal” mode is no longer supported. An example of a set of failures that will automatically drop the system into the ‘‘Secondary” mode is total loss of airplane air data from the ADIRU and SAARU. The airplane is quite capable of being flown for a long period of time in the ‘‘Secondary” mode. It cannot, however, be dispatched in this condition.
Direct—In the ‘‘Direct” mode, the ACEs do not process commands from the PFCs. Instead, each ACE decodes pilot commands directly from the pilot controller transducers and uses them for the closed loop servo control of the actuators. This mode will automatically be entered due to total failure of all three PFCs, failures internal to the ACEs, loss of the flight controls ARINC 629 data busses, or some combination of these failures. It may also be selected manually via the PFC disconnect switch on the overhead panel in the flight deck. The airplane handling characteristics in the “Direct” mode closely match those of the ‘‘Secondary” mode.
We talked about direct mode. If you attribute “knowledge” to the ACE’s, than this knowledge comes from the PFCs, which are not functional in direct mode.
But as I’m no expert on the flight control system in the B777 I’ll rest until Guarded Don has time to answer the question. It just looks unreasonable to me to operate the flaperons in an way as described. In the end they are not necessary at all to fly the aircraft and it would be more logical not to use them at all in direct mode.
@RetiredF4:
The PFCs also receive the feedback from the aircraft systems regarding control surface position, pitch and roll attitudes, rates-of-change, and rotational and linear accelerations, and modify the control surface movements in accordance with the airplane’s response in order to achieve the desired response.
@RetiredF4:
” If you attribute “knowledge” to the ACE’s, than this knowledge comes from the PFCs, which are not functional in direct mode. ”
The “knowledge” I attributed to ACEs concerned the hydraulics, in particular which PCUs were powered and for what function (ailerons or flaps).
Hacking everyday use technology for nefarious purposes is a common theme in fiction writing. The fly-by-wire technology of the modern jetliner has not escaped the notice of fiction writers. Lewis Perdue is one such writer who wrote the novel DIE BY WIRE in 2011. It revolves around the plot to make airlines disappear from the sky and short the stocks of particular airlines to make a profit in the stock market. The culprit in the novel was a sophisticated Islamic militant.
Hacking fly-by-wire technology may not be a particularly novel theme. But making a plane disappear, and leaving behind only the mystery does appear to be quite a unique idea. The author commented on this on his website in the aftermath of the disappearnce of MH370. Here is a quote from the author’s website ( lewisperdue.com ):
“..a lot of comments have been made about the absence of terrorist “chatter” and claims of responsibility. But maybe that’s the point.
Maybe the mystery IS the terror.
That was the point I made in Die By Wire.
My evil mastermind knew that it’s hard to top 9/11. People get inured … one more hijacking. One more building on fire. Been done. The shock gets absorbed.
Especially so because people push back against someone they can identify, can blame, can hate. Identifying someone to blame offers closure, psychological release where healing can start.
But making aircraft simply disappear gins up fear and distrust. The uncertainty of NO closure can be more painful and last longer than a spectacular blast.”
Interestingly, this book was published in 2011, and his other works are supposed to have been translated into many major languages. Wonder if this book was translated into the language of Dostoevsky.
@Gysbreght
Posted September 26, 2015 at 8:47 AM
@RetiredF4:
The PFCs also receive the feedback from the aircraft systems regarding control surface position, pitch and roll attitudes, rates-of-change, and rotational and linear accelerations, and modify the control surface movements in accordance with the airplane’s response in order to achieve the desired response.
I do not grasp what you are saying with the above comment.
The PFCs are lost in direct mode. Everything the PFCs do like described in your post is lost. Please explain, what kind of information will then enable the ACEs to counter the assymetry caused by a flaperon only extended on one wing in the flap mode or the different reaction of a wing with the flaperon as aileron and the other wing without it?
The only logic would be for the ACE’s not to use that remaining flaperon at all.
@RetiredF4:
I know that the PFCs are lost in direct mode. As I explained to GuardedDon, I’m not convinced that the ACEs reject the PFCs simply because the RAT is the only source of power. There is nothing in the FCOM to that effect, only GuardedDon’s “extrapolation” of information in the Maintenance Manual.
In Mr. Exner’s simulator tests there was an experienced pilot in the left seat, Mr. Exner in the right seat, and possibly one or two observers. Hard to believe that no one paid attention to the EICAS messages, and that nothing was recorded in the video’s for any of the tests.
Flitzer_Flyer
Posted September 25, 2015 at 3:07 PM :
“ “ELT’s in regards to aircraft accidents have had an 80% failure rate”
Yes, I understand that. There are references in the ATSB FI, the FAA website, and elsewhere. The point is that the ELT itself did not fail. It is the lack of transmissions that is the problem.
And this is exactly my point. Why were there no transmissions in this case?
– because the ELTs/cables/antennae were damaged in a crash, or,
– because the ELTs were under water in less than 50 seconds
– cabin crew unable to activate
– flight crew significantly distracted, or unable to activate manually.
If these are reasonable reasons, then a number of the “conspiracy” theories might be eliminated, as can any possibility of a soft “controlled” ditch.”
I see where you were headed with your original question now and it does warrant further discussion.
-Playing devils advocate, *if* the aircraft hit within the threshold trigger point for the auto activated ELT’s, and within range of its maximum rated shock load, then a unit that has been damaged or its cables or antennae is a failure of the ELT. Without wreckage recovery, one will never know what forces the A/C has been subjected to, so at this point, claiming non transmission as a failure is not quite correct.
-It could potentially sink prior to connection with Cospas-Sarsat. It has happened in the maritime environment, so it’s not without precedent.
-In regards to cabin crew and ELT’s, what is their SOP and where in the list of emergency procedure does manual activation of ELT’s occur. I wouldn’t think manual activation is high on the priority list until post impact, and manual activation would most likely occur via ELT’s in the rafts in a seaborne emergency due to an overwhelming desire to leave the stricken craft?
Flight deck activation pre/post accident of onboard ELT’s is one point you may have missed.
I do not think anybody could consider your listed reasons for failure unreasonable at all. However I cannot see (some) conspiracy theories and/or a soft ditch being muted on these points alone.
What would be interesting to research is why the 80% failure rate I mentioned in a prior post. My understanding (which could easily be proved wrong), is that the vast majority of thus were within design parameters and should have done the job as designed (both land and sea incidents) but for whatever reason, did not. It was one of the arguments going around in the earlier days as to why we don’t have real time global tracking of aircraft in this day and age. The local pizza delivery driver can be tracked in real time. Go figure.
sk999,
A while ago I was experimenting with the accounting for various “second-order” effects. If you don’t mind, I will denote here v – the aircraft’s velocity (vector) and u – exhaust velocity w.r.t. the aircraft (also vector).
Additional thrust due to the mass ejection is -u*q, where q = -dm/dt is the fuel flow rate (see, for example, hyperphysics.phy-astr.gsu.edu/hbase/rocket.html, or any other articles on jet propulsion). Thus, the 2nd Newton’s law is:
m dv/dt = F – uq,
where F is the external forces.
In the model I presented, I made an assumption u = -v, which I forgot to mention. Justification: I read somewhere that the exhaust speed of jet engines is slightly lower than the sound speed. This makes sense because of the optimization of the use of the energy (a fraction of the energy goes to the exhaust jet’s kinetic energy, and than dissipates). Under such an assumption:
m dv/dt = F + vq =>
m dv/dt = F – v dm/dt =>
d (mv)/dt = F.
I used exactly this form. I have to say, as expected, the effect is minimal, although it helps to decrease the residuals by 1% or so. Perhaps more accurate considerations of the exhaust speed will improve the results even further, but I would expect improvements to be of the same order.
Cheryl,
“It is correct according to the 4 Corners piece. It specifically states that the IFE was interfered with at the same time as the loss of the other comms but does not explain how.”
How could it be concluded that IFE went down at exactly the same time as SATCOM, HVF,…? Yes, it could. But did it?
Re: “In your query of the 18:25 – 18:27 IFE response, isn’t it doing exactly what it was designed to do”
Are we sure what it was designed to do? If it was ‘on’, it would reconnect to AES when the latter became ‘on’. If it was ‘off’, it would boot-up and then connect to AES. But only if power was supplied by IDGs or APU. The 90-second delay is likely indication that IFE was down, but here I cannot comment. Either way, it is not possible to say whether it went down simultaneously with SATCOM.
Re: ” I would think that regardless of where the IFE is getting it’s GPS information from ADIRU or wherever, it’s not playing if the AES is not operating.”.
Why not? The ‘data-3’ link would be down, and that is it, at least in my understanding. In other words sms/e-mail feature of IFE would not work. Map feature does not need ‘data-3’ link to function, does it? Btw, GPS is not ADIRU. B777 has 2 GPS and 3 ADIRUs if I am not mistaken. I guess Don has appropriate knowledge to comment how position/velocity data is fed (routed) into the IFE and AES.
@Sharkcaver,
I didn’t miss the possibility of flight deck activation. It was the 4th bullet point on the list.
The failure rate of ELTs is well documented, as I mentioned before. The failures are largely attributable to damage to the ELT antenna or cable arrangement in the event of a crash, or the ELT being under water. In all these cases the ELT itself may indeed have triggered, but there was no possibility of a successful transmission.
I am trying to point out that no ELT transmissions during the flight, especially after say 18:xx could point to an incapacitated flight crew, and cabin crew. And, no transmissions at the end of the flight would eliminate a soft controlled ditching.
@Flitzer
It is unlikely a 406MHz ELT would work inside an aircraft. The wavelength is long enough that the aircraft would act like a Faraday cage.
CliffG – if you can bring down a sophisticated drone designed to operate in hostile territory drone you can do the same to a 777? At least the flight path and behaviour of the plane makes a lot more sense viewed this way.
A while back I suggested that cutting down the Thai-Malaysian border took it away from Shah and or any political protest. If it was a domestic Malaysian issue I reckon you would refrain from implicating the air defenses of another country. If you were from another region however looking in, it makes a lot of sense. The plan it appears was to get the plane from A to B(wherever that was) and it might have worked.
I have a hard job separating the reboot from the southern leg. Siamese twins. I understand the caution in remaining open about causes for a reboot but this wasn’t a normal flight we already know. Someone was fiddling knobs here. Where were they at the time?
Regarding elt’s and no distress call – could be wrong to assume that crews nail everything perfectly when it hits the fan. Many planes have gone down from recoverable incidents because people made errors or were overwhelmed by the information pouring at them. As for the cabin crew?? Total panic comes to mind? When the unthinkable happens most people are useless. Only trained hardened nerves come through.
When a QANTAS A380 blew an engine a few years the cascade of issues from it was just scary. That plane could easily have crashed and a chunk of such instances might result in one. Worth a read.
Oleksandr,
Your 1st equation is basically what I was arguing is correct – as long as F only incorporates drag, gravity, and aerodynamic forces. The term “vq” is not “additional thrust,” it is the ENTIRE thrust (at least for a rocket or a turbojet – things get more complicated for a turbofan).
The article on rockets that you link to slides over some of the subtle details and could be written better.
@ Dennis,
“It is unlikely a 406MHz ELT would work inside an aircraft”.
You might be surprised how well they work. I once inadvertently triggered mine inside my hangar, which is just large enough for two small aircraft, then closed up the hangar and left. The hangar is clad, walls and roof, with galvanised steel. I was called out to see a rescue helicopter stationed outside the hangar, and the crew wanting to verify the activation. Embarrasing.
@Flitzer
lol.
A back of the envelop calculation showed that at 406MHz and a 12″ window size that it was close – certainly attenuation would occur. I think an experiment would need to be done validate operation. I would wonder what effect the lack of a conducting floor in the hanger might have.
Did you have to pay a fine or just get off with a wrist slap?
I am assuming that your airplane has an external antenna for the ELT?
@Dennis,
Reinforced concrete floor. Well earthed.
Just a wrist slap. S**t happens. There are many more inadvertent/accidental transmissions than real ones.
Nope. An internal antenna, but it is a GFRP aeroplane. Glass and foam sandwich, very much like the skin on a certain flaperon.
sk999,
No. ‘vq = -uq’ is not the entire thrust. It is part of the thrust. The principal difference of a rocket from turbojet is that turbojet uses ambient air for both oxidation and creation of the thrust, while a rocket does not.
For B777, the normal fuel flow rate roughly is q = 2 kg/s (subject to its mass). Can you imaging what exhaust speed would be required to create 400 kN thrust if turbojet relied on the same principle as a rocket?
Turbojet takes ambient air to generate propulsion, not only for oxidation. A problem with turbofan is that if tips of blades exceed sound speed, the respective areas of blades become useless: they do not create thrust. Turbofan uses similar principle, but it is enclosed, and the air characteristics inside of a chamber(s) are totally different.
With a fan diameter of 2.8 m, an engine can suck 1580 m^3 of air at 500 knot airspeed. Both the engines would suck up to 1.3 ton of the air per second at 10 km altitude. If the exhaust speed is 300 m/s, this creates the thrust of 390 kN – a figure consistent with the engines characteristics. But 2 kg/s is only a tiny addition to 1.3 ton.
LIVE NOW in NYC Central Park
all about 17 sustainable development goals
#globalcitizen
forgot link …Pearl Jam yet
https://www.youtube.com/watch?v=YAPukIWbYU0
ELTs and cabin panic
The quarter-wave length at 406 MHz is only about 7 inches and the portable antennas are typically about that size. So it would almost certainly work if brought to a window. Also the typical battery livetimes are around 10 years, so even with no maintenance from MAL, they would probably still work since 2002.
The issue of panic in the cabin is hard to speculate on. Probably there has never been a case where the aircraft was doomed, yet continued to fly for so long. Given the experience of UA 93, the perps would certainly try to neutralize the passengers if they had the ability to do so.
One can ask how the depressurization can be done by something other than flipping the switch in the cockpit. One possibility is to use a very small explosive device, just to blow a small hole. It would have to be carefully calibrated and placed. If it goes off and the pilots are prevented from making an emergency descent, it would at least neutralize all passengers relatively soon.
@Mike
Some info on decompression effects.
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.183.632&rep=rep1&type=pdf
To blow a hole into the cabin would have caused a permanently depressurized aircraft and would have hindered prolonged flight at altitudes above 10.000′ due to environmental effects.
@Jeff @Sajid UK
Re: “Yes, you are absolutely right. That first hour without satellite communication is a massive problem for this theory.”
(The theory of course being the, very remote, remote hijack)
I suggest that hour, without satellite communication (with one particular satellite) actually helps the theory. Perhaps the reason for no satellite communication with inmarsat from xxxx until yyyy is because the aircraft SatCom was retasked, talking directly with another satellite.
If a system like BUAP exists, I expect the inmarsat satellite would not be involved. This would be accomplished via military satellite or perhaps military aircraft.
As an example only – US military have 152 in orbit right now, no doubt, others also have many.
http://www.ucsusa.org/nuclear-weapons/space-weapons/satellite-database.html
Perhaps the reboot results from the end of communication with military satellite, waypoints set?
@Mike
“One can ask how the depressurization can be done by something other than flipping the switch in the cockpit. One possibility is to use a very small explosive device, just to blow a small hole. It would have to be carefully calibrated and placed. If it goes off and the pilots are prevented from making an emergency descent, it would at least neutralize all passengers relatively soon.”
You might check the reference below.
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.183.632&rep=rep1&type=pdf
A depressurized cabin poses multiple problems for humans, therefore a rapid descent to lower altitudes is immidiately necessary. The known O2 problem can be mitigated with the onboard systems for a limited time, but -60°C cabin temperature is hardly survivable for more than few minutes. According to the reference ambient outside temperatures will be reached in the cabin within one minute.
Decompression and longer decompression state without 100% O2 prebreathing causes severe decompression sickness. Perps would know such things.
A cabin with a hole in it cannot be pressurized again. As we assume that the hour long flight was performed at cruising altitude the depressurization, if one occurred, had to be reversible.
@Mike & Flitzer
The ELT question is certainly an interesting one. I think we can all agree that electromagnetic radiation is tricky sh*t to model.
The rule of thumb for a square hole is that the cutoff frequency is approximated by:
FC ~ 150000/(length) MHz.
Where length (of the square side) is in millimeters. For a 12″ hole FC is about 500MHz.
Of course, the cutoff frequency is not a cliff. Meaning that the attenuation begins at 500Hz, and becomes greater at some 12dB per octave as the frequency drops below 500MHz. So radiation at 400MHz will definitely get out, albeit with attenuation.
A good readable summary article is in the link below.
http://www.formfactors.org/developer%5Cspecs%5Cwg_overview_098.pdf
Another consideration is the orientation of the aircraft. If flying North to South (general ATSB/IG direction) one could postulate that a reasonable view of equatorial satellites is obtainable through the windows. Flying East to West close to the equator would have satellite visibility problems since the satellites would be above the aircraft without a direct line of sight.
Coupled with all the above are observations like Flitzer’s where a 400MHz ELT worked inside a metal building. There are reports of ELT’s going off and being received while inside a metal file cabinet. Hmmm…
Note: I will not use the failure of ELT reception (from inside the cabin) to bolster my theory that the plane was flying East to West along the South coast of Sumatra. 🙂
Mike, the physical size of the antenna is not a good metric for the “effective” size. I have used very small GPS antennas that have a thick ceramic over the square metal patch antenna below the ceramic. The ceramic acts like “lens” to magnify the size of the square patch. I have not looked at the construction details of ELT antennas(1) to see what tricks are being played there.
(1) Antennas is reserved by engineers as the plural form of antenna. Antennae is reserved by biologists for the plural form of an insect antenna.
@Dennis,
The Cospas system has both geostationary and LEO satellites. N-S, vs E-W is not an issue.
The performance of a waveguide beyond cutoff also depends on the length. An aircraft window has virtually no “length”.
The ELT manufacturer of those on board was a French company, ELTA. They have pics on their website of typical antennas. The portable type are more likely 5/8 wavelength at 406, and they also incorporate a loading coil to radiate on 121.5 as well.
Handheld PLBs are rather different with their little foldable antenna.