Well, we’ve been saying it here for a long time, but at last the ATSB has ackowledged the inevitable truth: the failure to locate any wreckage on the seabed in the southern Indian Ocean will mean that MH370 must have been piloted until the very end.
To quote today’s story in the Independent:
“the possibility that someone was at the controls of that aircraft on the flight and gliding it becomes a more significant possibility, if we eliminate all of the current search area.” [Martin Dolan, chief commissioner of the ATSB, told The Times.] “In a few months time, if we haven’t found it, then we’ll have to be contemplating that one of the much less likely scenarios ends up being more prominent. Which is that there were control inputs into that aircraft at the end of its flight.”
To be clear, Dolan wasn’t saying that they’ve ruled out the ghost ship yet, but seems to be preparing the public for this eventuality when the search runs out of money and time this June. But the fact that he said it all suggests that he views it as quite a likely outcome.
The only “much less likely” scenario that Dolan pointed to was the idea that a suicidal pilot might have flown to seventh arc within the current search area, then held the plane in a glide after it ran out of fuel so that it wound up some distance beyond. If such was indeed the case, then the area to be searched would be too large to be economically viable. This led to some catastrophic headlines, such as Bloomberg‘s “Missing Malaysia Jet MH370 Weeks Away From Keeping Secrets Forever.” But this is a tad presumptious, in my opinion.
Though Dolan didn’t ennumerate them, there now three scenarios that could match the data we have in hand.
1) The one Dolan described, which we might call “straight and fast.”
2) Another controlled-flight-into-the-southern-ocean scenario, which I’ll call “slow and curvy.” This would result in the plane ending up further to the northeast, and would necessitate an even larger search area.
3) A “spoof” scenario, in which sophisticated hijackers tampered with the satellite communications system and hijacked the plane to the north.
While some at the ATSB (and maybe within the IG, too) might be wearing long faces over Dolan’s admission, in my estimation it marks the most hopeful turn in the case in a very long time. As David Gallo recently pointed out on Twitter, the ATSB search hasn’t failed to locate the plane; it’s succeeded in proving where the plane isn’t. The most likely scenario — the scenario that we’ve been told is the only reasonable one — the scenario that we’ve been told will imminently be proven correct — has been falsified. And that brings us one very big step closer to finding the truth.
The illusory “sure thing” is over. (The wonderful film The Big Short, which I saw over the weekend and which I think any MH370 obsessive will find very entertaining, at one point quotes Mark Twain: ‘It ain’t what you don’t know that gets you into trouble. It’s what you know for sure that just ain’t so.’) It may make some people uncomfortable, but we now know that whatever happened to MH370, it was weird and unprecedented.
Now we can get down to work. I hope that now that the broad community of MH370 researchers, and especially the hardworking and intelligent folks at the ATSB, can embrace a new spirit of enthusiastic skepticism and turn their attention to fully evaluating all of the possibilities.
There is some important information coming down the pike that will be very illuminating, and I am very excited about pressing this story forward in the weeks and months ahead.
Gysbreght,
Wind speed changes quite a bit with altitude – I get 7 knots at the 17:30 position and latitude for FL320, down from 15 knots at FL350, which accounts for the difference.
sk999,
what leads you to FL320?
Minor correction – I actually computed the route.csv file for FL310, where wind speed was 5 knots at 17:30. The actual altitude (which is what radar would report) was approximately 33,000 feet. This is in the middle of the range reported in Factual Information. The winds and conversion to actual altitude are taken from the GDAS model.
@All,
I take issue with the “anywhere within 100 miles, in any direction” glide theory.
First of all, it’s anywhere not within the original 20 of the ping ring, because that’s already been searched.
Second, even if it is possible for it to have glided in any direction, there’s a high likelihood it continued in the same direction. Here, the motive for the glide kicks in, but the only reasonable motive available to us is “keep the plane in the air.” That suggests that the plane glided as far as the pilot’s experience could take it, which again requires knowing who was piloting.
But let’s say we had a disoriented pilot thinking he’s on his way to Christmas Island. He’s not going to U-turn when he runs out of fuel. He’s going to glide as far as possible.
So while the area of possible glide landings is huge, the area of probable ones is pretty narrow unless someone has an alternate theory of motive *at that stage of the flight* other than stay alive.
One could attempt to sample the glide distance with 100 trips to the simulator. The search need only be centered on the mean of that sample – probably 90 miles SE of the ping ring.
My main point is that with two reasonable assumptions – the pilot was at the stick, and he wanted to go as far as possible – the additional search area is narrow.
Don’t like these assumptions? Fine, but then you have trouble fitting a glide into the equation at all.
@JS: Once you base your scenario on a piloted flight to the SIO, it is futile to use logic to limit where the piloted might have glided because all logic must be thrown out the window. Plus, there would be no preference for a straight flight. The entire scenario defies logic, and the possible range of endpoints is unmanageably large.
@jeffwise – Couldn’t the flaperon have been caught up in cold water gyres for 9 months or so before drifting into waters warm enough to support barnacles?
China’s actions in the aftermath of the disappearance of MH370 suggest a pattern of deception. I have prepared a timeline of events to illustrate this. We have to question China’s motive for these actions.
https://www.dropbox.com/s/4ubbg0bo7zvidrk/2016-01-05%20Timeline%20of%20MH370%20and%20China.pdf?dl=0
China’s actions in the aftermath of the disappearance of MH370 suggest a pattern of deception. I have prepared a timeline of events to illustrate this. We have to question China’s motive for these actions.
https://www.dropbox.com/s/lxymbeyyz3tdiwt/2016-02-20%20China%20and%20MH370.pdf?dl=0
(The previous post had an incorrect link.)
@Victor – I disagree. I don’t believe you need to throw ALL logic out the window, nor does the situation entirely defy logic.
We have three scenarios – one in which the flight was piloted both before and after fuel exhaustion, one in which it was piloted only after fuel exhaustion, and one in which it was a ghost ship. The ghost ship scenario is excluded for purposes of this discussion.
In both remaining cases we think we have a ring of locations at which fuel exhaustion occurred, and in either scenario we have a piloted glide after fuel exhaustion. The pilot (or pilot-autopilot combination) was skilled enough to reach the 7th arc in the first place, and showed some intent to go in a general SE direction.
Some weight should be given to the general direction of the plane prior to the 7th arc. More skill and a motive are needed to glide the plane to a location behind the 7th arc, or to a location beyond the arc but not the maximum glide distance.
Some weight should also be given to the idea that the longer the glide, the better the piloting, the better the ditching, and finally the more likely the plane landed in bigger pieces.
None of this eliminates any location within 100mi of the arc, but it should provide a higher probability band, and I would argue that such a band is narrower than the one being searched now and that it could be scanned at lower resolution.
Dennis,
Re #2. If you consider ground speed constant 900 kph, the length of respective segment will be 900 km. If you consider speed 700 kph in the beginning and 900 kph at the end of a segment to fit BFO, what will be the length of this segment?
Re #3. “Switching on the APU when you know you are running out of fuel is not something that would make much sense. You know that it too is going to stop working very soon. What would be the point of it?”
To avoid power interruption. Only essential flight instruments can be powered by RAT and batteries. If only xx miles remains to a destination after the flameout of the first engine, then it makes sense to save every drop of fuel; in such a case I would agree with you. If, however, xxx miles remains, then there is no chance to reach intended destination, so it is better to ensure all the equipment is functional as long as possible.
@Oleksandr
re#2 – It would depend when the transition from 700 kph to 900 kph was made. The length of the segment can be anywhere in the range of 700km to 900km if only a single transition is used. It can by almost any length (depending on the performance limits of the aircraft) if more than one transition is allowed.
You are splitting hairs on the APU issue. It has little to no relevance in my world. My sense is the PIC would have a lot more to worry about once the first engine experienced fuel starvation than whether he should start the APU or not.
@JS: It’s simple. If you can’t provide a logical reason to pilot a plane to the SIO, it is not likely that logic will kick-in once the plane runs out of fuel. I wish we were not in this situation, but we are. Let’s be realistic.
@VictorI. – great summary of China’s deception. Make one wonder why they needed to do that.
Dennis,
Re #2: Exactly. Consequently:
– What would be a reason for PIC to keep on changing speed?
– Have you compared with the lengths of your path segments?
Re #3: “My sense is the PIC would have a lot more to worry about once the first engine experienced fuel starvation”.
About what? Life of passengers – apparently no; communication with ATC – no; restarting engine – for what if they ran out of fuel; descending – that requires only a simple input into AP. What else?
BTW, if I am not mistaken APU can power hydraulic system, and thus pilot can ensure stable gliding. RAT is insufficient to manage control surfaces, so that ensuring stable gliding would be a way more complex task.
@MH: Yes, China is high on my list of suspects based on the pattern of deception suggested by the timeline of events.
Oddly, after I started assembling the list, I viewed Malaysia’s actions in the aftermath of the disappearance in a different light. China was promoting a crash in the SCS and the US was trying to move the search to the Indian Ocean. Malaysia initially was swayed by China, but the US applied pressure and was successful in moving the search away from the SCS.
The US has tremendous leverage over Malaysia as Najib is one Justice Department indictment away from becoming declared a wanted criminal. The corruption of the 1MDB is well-documented in publications like the WSJ, and there is a grand jury already formed in the US to look at criminal assets acquired by Najib in the US.
@alsm
“1. After the FMT, the plane descended to a much lower altitude and corresponding lower speed and crossed the 7th arc much further north. (Possible, but unlikely.)”
Good! But if you say it’s possible, why would it be unlikely?!
@IR1907
“No one outside Inmarsat (and perhaps Air France) would have known anything about the BFO-BTO. But why again would anyone with half a brain let a communication device (well, sat phones got through) stay on if he wants to dissapear completely, that doesn’t make any sense, does it ?”
exactly, that’s why I’m quite confident disappearance was planned to be only temporary but unfortunately the plan hasn’t worked that well..
@Oleksandr
Keep changing speeds? I think I have at most three speeds referenced in my table. That would imply two speed changes. i change speeds more often than that getting down my driveway, and it is less than a mile long. If you have something on your mind Aleksandr, come out and say it. Quit nit-picking.
PIC can do whatever he wishes. My segment lengths are approximately compatible with the speeds listed in the table. Check it out.
It is called “The Miracle on the Hudson” for a reason. Aviate, navigate, communicate. You might notice that communicate is third on the list. I would imagine an engine flameout due to fuel starvation would initiate a relatively stressful chain of events.
Yes, my understanding is the APU does power the hydraulics.
Victor,
“Malaysia initially was swayed by China, but the US applied pressure and was successful in moving the search away from the SCS.”
Really?
Dennis,
Re: “My segment lengths are approximately compatible with the speeds listed in the table. Check it out.”
That is what I was asking. Have you compared this already? Where I can see the comparison?
Re: “Yes, my understanding is the APU does power the hydraulics.”
Then why APU was off? To make things worse by making aircraft uncontrolled?
“Communicate” was not apparently in the list. “Navigate” – likely not. Navigate to where? Only “aviate” would be in the list.
@DennisW: US1549 cannot be cited to explain why there was no communication from MH370 after fuel exhaustion. In fact, the sequence of events of US1549 suggests that there SHOULD have been communication from MH370.
US1549 was flying at an altitude of 3000 ft and a speed of 185 KIAS when the A320 struck the flock of birds which caused both engines to flame out. This is much lower and slower than MH370 would have been flying upon fuel exhaustion, and happened with no warning. (The MH370 pilots would have had ample warning of the impending fuel exhaustion.) Yet, Capt Sullenberger had the time to declare “Hit birds. We lost thrust on both engines. We are going back to LaGuardia.” He then later advised ATC of his desire to make an emergency landing at Teterboro Airport in New Jersey, before later advising that he could not reach Teterboro and would be landing in the Hudson.
@VictorI
we don’t know if whoever was the PIC had the fully working plane at the moment, maybe even communication equipment was hit by fiddling with CBs in E/E bay
@Victor
Good points, and I acknowledge that when Aleksandr raised the issue. I am still thinking about it. Of course, US1549 was already in communication with ATC at that time. All Suilly had to do was speak. When MH370 fuel exhaustion occurred there were a number of things that needed to be done to initiate communication. Communication was not anticipated at the moment MH370 ran out of fuel. Big difference.
Also, I wonder about your statement that the MH370 pilot(s) had ample warning of fuel exhaustion. I have looked pretty hard relative to what constitutes what we would call a “gas gauge” in a commercial airliner. Do you have a link to any info on this. I have concluded that fuel remaining is calculated by knowing how much fuel you started with and then using accurate flow meters to infer fuel remaining. The flow meter accumulator could have been screwed up by whatever bizarre events took place before 18:25. I would not be prepared to make the statement that the MH370 pilots(s) were keenly aware of how much fuel was remaining. I am not challenging you here. I am simply asking because I have looked relatively hard with nothing to show for it. Your response would be very interesting to me as well as anyone else who cares to weigh in on this question.
@Oleksandr
Yes, of course, my table was based on these measurements and calculations (speed and segment lengths). Could I have made a large error? Sure. If I did, please point it out to me, and I will attempt to deal with it.
RE: Communication: Consider the reasons Capt. Sullenberger had to communicate with ATC and the assistance ATC had to offer. None of those existed at MH370 fuel exhaustion. With whom communicate, by what means, and for what purpose?
For Fuel-Controls and Indicators see FCOM section 12.10:
In addition (I believe) the fuel consumed obtained from the fuel flow transducers is integrated and subtracted from the fuel on board at takeoff, and there is a warning if the fuel remaining differs too much from the fuel quantity indication.
@Sharkcaver
Interesting that you mention David Mearns. He noted his concern, in one of the early blog posts journalling the HMAS Sydney search, that the ‘rugged’ bathymetry initially encountered might severly hinder the prospect of locating the warship.
As their search progressed the seafloor ran out to abyssal plain where they found HMAS Sydney.
@Jeff
The search is amassing a vast sonographic record, it’s quite different to a photographic record. Similar to your suggestions/expectations, I earlier set out what should be expected as a search progress report from ATSB. Havila Harmony continues to deploy its ES7 AUV along the GFZ which runs through the original 60,000km/sq area.
Which country might provide Najib safe heaven when it gets too hot for him? Once he is out more info may come out MH370.
The HMAS Sydney search was a much smaller affair with a fraction of the budget and any complication had the potential to derail it. Could the Havila Harmony be revisiting some of the tricky areas as advised by Fugro some weeks back?
Fugro are tasked with bringing back imagery of the whole search area, not just the easy bits. If this was not a realistic undertaking I believe we would have heard about it by now. But something is wrong here: The SIO hypothesis hinged on likelihoods and probabilities as assessed by researchers all tallying up to reach a certain end point. Now that we have nothing, the low probability scenario(missed debris) is all the rage?
@StevanG & @DennisW: I only brought up US1549 because it was an example that @DennisW raised for why there was no communication from MH370. In fact, US1549 demonstrates that communication is possible in very dire situations.
According to posts on PRUNE.NET, a FUEL QTY LOW message appears on the Engine Indication and Crew Alerting System (EICAS) display when there is less than 4500 lb of fuel in either the right or left fuel tank. I do not know if there is also an audible alarm.
@VictorI,
Master Caution lights and audible beeper activate for low fuel quantity.
OZ
@victor
Your metaphor is misplaced. In no way does your example correspond to MH370.
Likewise with fuel exhaustion. Please respond to the direct question. How is remaining fuel measured, and how accurate is that measurement?
Sorry, but when you step into the fray you get queried harshly. Time to take the gloves off even if you are an IG member and Jeff likes you.
@Oleksandr,
Readers digest version!
The ADIRU initialisation or alignment establishes the relationship between the aircraft and its geographic position/direction. This is accomplished with aircraft on ground and stationary; no movement. Alignment cannot occur with the aircraft moving (therefore in flight).
Multiple redundancies ensure that power is always available to provide ADIRU functioning. If all fail you have SAARU for attitude (and a short duration of direction).
The simplest way the ADIRU knows it is in flight or not is WOW (Weight on Wheels).
My understanding is that the ADIRU input to SDU is for position to assist the high gain antennae steering for satellite acquisition (simplifying the search limiting possible targets). If all ADIRU inputs are lost the SDU reverts to data tables for tuning (all satellite targets are searched).
OZ
More off-topic rambling here.
How could the plane have ended up in true track mode**, which would be needed to reach the high priority search area? It has been suggested that, at some point after the diversion, waypoints were entered in the FMC, but the plane overflew the last waypoint. What happens next? The documentation is a bit ambiguous, but I did finally locate the following in the Qatar FCOM – this is the FMC message that would be displayed and its meaning:
“END OF ROUTE – LNAV active and end of active route overflown. AFDS maintains last heading.”
So it is the AFDS that is in charge, with the roll mode being HOLD. [As an aside, the B-737, the B-747, the Airbus A320 work this way as well.] On the B-777 MCP, the choice between HDG and TRK modes is made by one switch, while the activation of HOLD (in whichever mode is chosen) is done by another switch. Would the AFDS always set the roll mode back to HDG, or would it simply use the last entered setting? Let us assume the latter (and some posts on other boards describe it as working that way.) What about TRUE vs. NORM? This setting is controlled by yet another switch, but it is not part of the MCP, and is instead located on a different panel. In normal operation, this switch is in the NORM position, and from what I can tell from reading pprune, it is never touched, even for planes that fly polar routes. It would have to have been switched deliberately.
I would propose that a scenario of an accident combined with a true track route South to the current high priority area can be ruled out. Either the diversion was deliberate, or the plane is elsewhere, or both.
**A great circle route would also work but would also have to have been entered deliberately.
From Dave Whittington’s simulation, it appears that the 777 “gas gauge” is in the center console, measures remaining fuel in pounds and shows the amounts for each fuel tank.
https://vimeo.com/98984695
@Lauren H, It sounds like a reasonable idea but I haven’t seen any drift models that are compatible with it — stuff south of 30S (where it would be suitably cold) quickly gets pushed north in that part of SIO.
@DennisW: It was you who first cited the US1549 to explain no communication from MH370. In fact, US1549 would indicate that communication is POSSIBLE under high stress. So if you now believe the metaphor is misplaced and doesn’t apply to MH370, that’s fine with me.
As for fuel gage accuracy, MH370 was loaded with 49,700 kg (109,471 lb) of fuel. The low fuel message would alert the pilot when there was 9,000 lb of fuel left, or after the plane consumed 100,471 lb of fuel. If the fuel metering system had an accuracy of roughly +/-1%, that would mean the low fuel message would come on when there were between 8,000 and 10,000 lb of fuel remaining. That represents about 40 minutes of flying time, depending on altitude and speed. With that kind of advance warning, it is hard to imagine how a pilot would not know he or she was going to run out of fuel and take appropriate action to land at a nearby airport, independent of the whatever the precise accuracy of the fuel metering system is.
If you want to believe that there was some event that compromised the fuel metering system before 18:25, we have to ask ourselves what event would compromise the fuel metering yet would allow the plane to fly until at least 00:19?
@Oz: Thank for your confirmation of audible and visual alarms for low fuel beyond the EICAS display. It would virtually impossible for a pilot to not be aware of a low fuel condition.
@VictorI
Thanks for your great list of items re: China.
One more China-related item; I am hoping that you have more detail or could shine some light on this please:
I am still not convinced that the flaperon found at Reunion was on that plane on that flight but it has been confirmed that one of three numbers corresponds to a number on an original flaperon for that plane. I think Lauren H was the first to point out that it was “original”. See Le Monde article by Florence de Changy on 4th Sept 2015. (link in next post)
“Selon le communiqué du parquet de Paris, « l’audition d’un technicien de la société ADS-SAU a permis d’associer formellement l’un des trois numéros relevés à l’intérieur du flaperon au numéro de série du flaperon du Boeing 777 du vol MH370 »”….
“Les experts avaient également confirmé que la date de fabrication du flaperon correspondait à celle de l’avion, construit en 2001 et livré à la Malaisie en 2002.”
Translation by Google: The experts also confirmed that the flaperon manufacture date corresponded to that of the plane, built in 2001 and delivered to Malaysia in 2002.
It has been reported that this aircraft (9M-MRO) was involved in an accident in China in 2012 and the right wing was damaged.
http://aviation-safety.net/wikibase/wiki.php?id=147571
If this is true, is it likely that the whole wing was replaced or just parts? And would any replaced parts remain in China or be sent back to Malaysia? A great pity (or very convenient) that the Malaysian maintenance records were lost!
See also the Le Monde article of 3rd Sept and translation in one of Jeff’s earlier sections.
@VictorI
Le Monde article 4th Sept 2015.
http://www.lemonde.fr/asie-pacifique/article/2015/09/04/le-flaperon-retrouve-a-la-reunion-appartient-bien-au-boeing-777-du-vol-mh370_4746144_3216.html
@Victor – your China analysis is right on. Thanks for a great summary.
China doesn’t want to contribute to the SIO search because they know the plane is not there.
However as long as the search focuses on the SIO they know their secret is safe. China is the only state actor with both the ability to commit this act and to keep it secret. I believe the plane flew on the northern arc on a remote hijack. The plane either made a hard or soft landing. What if we re-assembled the evidence with that assumption? Jeff was right, the plane did head north.
Your analysis of the 7th arc with 0 fpm vertical and 0 BFO shows an endpoint in Tibet/Xinzhang). Your map also seems to indicate that a southern landing is hard (-5k fpm vertical) and a northern landing is soft (0 fpm vertical). I’m not sure why we are discussing a glide in the south where the BFO indicates a rapid descent.
Oz,
That does not answer my question!
From the video, link to which I posted, you can derive a few things:
1. The instructor says that ADIRU must be initialized each time on power up. I don’t know whether it implies ADIRU selector position “off” or also global power up.
2. Given the existence of “off” position, it appears ADIRU can be switched off by pilots any time. Is this correct?
3. ADIRU has to know position, direction of the north, and orientation of aircraft for the alignment.
4. During alignment process, ADIRU can detect and account for Earth rotation.
5. During alignment ADIRU can detect movement, and restart alignment.
6. Pilot can either manually enter coordinates, or let ADIRU automatically read it.
7. Pilot cannot enter ground speed. At least I did not notice this. As it would be logically expected.
8. Alignment process takes about 5 minutes at the equator, and up to 17 minutes at high latitudes for the ADIRU model discussed in the video. The 5 minutes at the equator is a very interesting number: 18:22 + 5 = 18:27.
Yes, you are right with regard to wheel load. Wheel rotation sensor would also be required in such as case. Don’t tell me the sensor is located in the nose landing gear compartment!
Either way, my question stands: what does prevent re-initialization in the air: (a) ADIRU itself detects motion and refuses to proceed; (b) external hardware/software/sensors; (c) pilot?
Re: “My understanding is that the ADIRU input to SDU is for position to assist the high gain antennae steering for satellite acquisition”.
Not only:
– Position is required for antennae sterring as you said;
– Position and ground velocity (horizontal comlonents) are required by AES Doppler compensation software.
In case ADIRU fails or switched off, or in the process of initialisation, where does AES take data: SAARU or GPS?
Finally, how does ADIRU synchronise with GPS? Or it does not, so that priority is given to ADIRU when it is available?
I’m new to all this and am hoping someone can explain why there is so little talk about a ghost flight ending northeast of the current search area (eg: on the 7th arc, but north of 35.5S). I ask because I thought the following were pretty convincing arguments for a northern terminus:
1. Richard Godfrey’s January IG studies overview, suggesting the most probable autopilot modes would put the plane between 36S and 29S at the 6th arc (and I guess between approximately 36.5S and 29.5S at the 7th arc).
http://www.duncansteel.com/archives/2152
2. Brock McEwan’s December analysis of various drift studies indicating the flaperon was extremely unlikely to have come from the current search area south of 35S, but could have come from from areas further north:
https://drive.google.com/file/d/0B-r3yuaF2p72RnNtRVZuSVdHaG8/view?pref=2&pli=1
Is there something about these northern paths that requires pilot intervention?
Victor,
Your perception about China involvement is totally wrong.
The search first was focused on SCS where the contact was lost. Isn’t it a logical choice? China has nothing to do with this. In fact they tried to help: sent patrol ships to scour SCS, provided satellite imagery.
After that Malay military released radar data, and the search shifted to the Andaman Sea. Did you forget that US Navy ships moved to the Andaman perhaps earlier than anybody else? Chinese arrived much later. Certainly not under US pressure, as you said.
And only after that Inmarsat concluded that the aircraft was in the air till 00:19 and likely ended up in the SIO. It was Australia and US, who discarded the pings at 25S detected by Chinese for a not very convincing reason. Could the aircraft end up at 25S? Certainly yes.
Yes, Chinese may know more than they tell us. Yes, their involvement and treatment of its citizen is quite dissapointing in this case. But you need to put aside you personal issues with Asians and Muslims.
The autopilot and the Flight Management Computer are both parts of the AFDS. The pilot controls how the AFDS operates.
LNAV is an autopilot roll mode that is controlled by the FMC, which navigates along a great circle route between waypoints, or maintains the last heading if the last waypoint is overflown.
In autopilot roll modes other than LNAV the pilot selects a heading or track on the MCP. To obtain true track he must select the TRUE position of the TRUE/NORM switch.
Gysbreght & sk999
The AFDS and FMC are separate systems, the AFDS is concerned with primarily with autoflight whereas the FMC function is primarily navigation and performance.
The B777 FMC defines a MV leg, a magnetic vector. In essence, it reverts to this leg type at route discontinuity, holding the heading when over flying the final waypoint. The AFDS mode remains LNAV. The outcome is the same as reverting to AFDS HDG HOLD but navigation control remains with the FMC.
:Don
DennisW,
The B777 Fuel Quantity Indication System was hailed as a great innovation when Smiths Aerospace delivered it. It exploits ultrasound to sense fuel level in perforated tubes located throughout the tanks.
Smiths claimed accuracy of 1%.
:Don
GuardedDon,
“The AFDS and FMC are separate systems”
Thanks for that correction.
@EricB, With regards to #1, Richard Godfrey in the overview you refer to rather disingenuously left out the fact that the autopilot modes that resulted in endpoints northeast of the current search zone required substantial changes in engine thrust in order to match the BTO ping rings. In other words, they require a person to actively work the throttle, and so are not really what most of us think of as “autopilot” modes at all. To answer your question: yes, they require pilot intervention.
Wrt #2, one upshot of Brock’s analysis is that if the flaperon’s journey originated in a higher-probability area of the seventh arc, that is to say closer to the northwestern corner of Australia, we would have also expected to see other pieces of debris wash up in places like Sumatra. I mentioned in a comment yesterday that the apparent youth of the barnacles fits better with a planting scenario than a crash-in-the-SIO scenario. Many believe the fact that exactly one piece of debris has been retrieved also fits better with a planting scenario.
jeffwise,
You write with regard to #1 that the curved paths ending more north require a person to actively work the throttle to make substantial changes in engine thrust. Is there a study showing that?
@Gysbreght, There isn’t a study showing that, I’ve heard it informally from people who have looked at the scenarios. In my experience, it is difficult to find routes that match both autopilot settings and throttle settings well. (Dr Bobby’s very-straight-and-very-fast scenario works best IMO but it would seem to require too much fuel.) I think it would be great if someone would conduct such an analysis, I’d be more than happy to put it up on the site as a guest post. Better yet, someone else might volunteer to double-check the results to make sure the results are rock solid.
@AM2, I can’t really get into specifics, having been sworn to confidentiality, but I’ve seen the photographs of the inside of the flaperon, and the corresponding records, and they do seem to confirm that the flaperon came from 9M-MRO, the airframe that flew as MH370. I think it’s safe to say that this was not one of the parts replace after the 2012 incident you mention.
It’s worth noting that while the French authorities appear to have been willing to leak information confirming the identity of the flaperon, they have been considerably more reticent regarding their findings about how the flaperon was damaged, marine life analysis, flotation studies, etc.