Last week we discussed what we know about the first hour of MH370’s disappearance, based on primary radar data and the first Inmarsat BTO value. Today I’d like to talk about the BFO data and what it can tell us about MH370’s fate.
As longtime readers of this blog well know, the Burst Frequency Offset (BFO) is a type of metadata that measures how different the frequency of an Inmarsat signal is from its expected value. It is an important value to a communications satellite operator like Inmarsat because if the value gets too large, the system will be operating outside its approved frequency limit. One cause of such a change would be if a satellite begins wandering in its orbit, which indeed was the case with MH370. The fact that the Satellite Data Unit (SDU) aboard MH370 did not properly compensate for drift in the Inmarsat satellite overhead is the reason the BFO data contains a signal indicating what the plane was doing.
While each of the BTO values recording during the seven “pings” tells us fairly precisely how far the plane was from the satellite at that time, the BFO data points taken individually do not tell us much about the plane was doing. Taken together, however, they indicate three things:
- After the SDU logged back on with Inmarsat at 18:25, the plane took a generally southern course. If we didn’t have the BFO data, we wouldn’t know, from the BTO data alone, whether the plane followed a path to the north or to the south (see above.)
- The plane had turned south by 18:40. The BFO value at the time of the first incoming sat phone call at 18:40 indicates that the plane was traveling south.
- At 0:19:37 the plane was in a rapid and accelerating decent.
However, as I’ve previously described, if all of these things were true, then the plane would have been found by now. So at least one of them must be false. In the course of my interview with him, Neil Gordon said that the ATSB is firmly convinced that #3 is true, and that as a result he suspects that #2 is not. Specifically, he points out that if the plane were in a descent at 18:40, it could produce the BFO values observed. Thus it is possible that the plane did not perform a “final major turn” prior to 18:40 but instead loitered in the vicinity of the Andaman Islands or western Sumatra before turning and flying into the southern ocean. If this were the case, it would result in the plane turning up to the northeast of the current search area. An example of such a route has been described by Victor Iannello at the Duncan Steel website.
It is worth nothing that such a scenario was explicitly rejected as unlikely by the Australian government when they decided to spend approximately $150 million to search 120,000 square kilometers of seabed. The reason is that it was deemed unlikely that the plane would just happen, by chance to be descending at the right time and at the right rate to look like a southward flight. For my part, I also find it hard to imagine why whoever took the plane would fly it at high speed through Malaysian airspace, then linger for perhaps as much as an hour without contacting anybody at the airline, at ATC, or in the Malysian government (because, indeed, none of these were contacted) and then continuing on once more at high speed in a flight to oblivion.
Well, is there any other alternative? Yes, and it is one that, though historically unpopular, is becoming imore urgent as the plane’s absence from the search area becomes increasingly clear: the BFO data is unreliable. That is to say, someone deliberately altered it.
There are various ways that we can imagine this happening, but the only one that stands up to scrutiny is that someone on board the plane altered a variable in the Satellite Data Unit or tampered with the navigation information fed back to the SDU from the E/E bay. Indeed, we know that the SDU was tampered with: it was turned off, then logged back on with Inmarsat, something that does not happen in the course of normal aircraft operation. It has been speculated that this depowering and repowering occurred as the result of action to disable and re-enable some other piece of equipment, but no one has every come up with a very compelling story as to what that piece of equipment might be. Given the evident problems with the BFO data in our possession, I feel we must consider the possibility that the intended object of the action was the SDU itself.
When I say BFO tampering has been “historically unpopular,” what I mean is that almost everyone who considers themselves a serious MH370 researcher has from the beginning assumed that the BFO data was generated by a normally functioning, untampered-with SDU, and this has limited the scenarios that have been considered acceptable. For a long time I imagined that search officials might know of a reason why tampering could not have occurred, but I no longer believe this is the case. When I questioned Inmarsat whether it was possible that the BFO data could have been spoofed, one of their team said “all Inmarsat can do is work with the data and information and the various testings that we’ve been doing.” And when I raised the issue with Neil Gordon, he said, “All I’ve done is process the data as given to me to produce this distribution.” So it seems that the possibility of BFO spoofing has not been seriously contemplated by search officials.
If we allow ourselves to grapple with the possibility that the BFO data was deliberately tampered with, we quickly find ourselves confronting a radically different set of assumptions about the fate of the plane and the motives of those who took it. These assumptions eliminate some of the problems that we have previously faced in trying to make sense of the MH370 mystery, but introduce new ones, as I’ll explore in upcoming posts.
@Nederland
It doesn’t work like that. Because of the partial pressure of gases and the way in which a human body absorbs oxygen, at sea level blood is 98% saturated with oxygen. At 25,000 feet (even though the proportions of gases in the air remains the same) blood is only 9% saturated with oxygen – at 35,000 feet, lungs are not able to process the oxygen at all, because the atmospheric pressure (approx 0.3 atm) is too low for oxygen and CO2 to be transferred to/from blood. Without pressure breathing apparatus, oxygen bottles are useless.
In these circumstances hypoxia would kill everyone long before ‘altitude/decompression sickness’ became a problem.
@Nederland, At Igari I believe altitude was 35kft (not 30k ft) and it made a turn ascending. With fuel load I understood that the ascent would be maxed at 37k ft. That’s all I know, the rest would be speculation on my part. But assuming depressurisation was commenced a few minutes before Igari at the altitude it was flying, TUC would be much shorter. Literally seconds.IMHO, an event like that would maybe not be noticed soon enough to don oxygen masks. Alternatively, if it occurred before or around FMT, the hijackers/culprits would have succumbed with the rest of the PAX.
Ok, conventional oxygen systems may not work much above 30.000 ft (but others quote different figures more like 35.000 or 37.500). But then again, MH370 was reportedly flying at around 30.000 ft. The cabin was presumably pressurised by the time of the last radio transmission and then it would take several minutes to depressurise if the outflow valves were opened and MH370 was gradually desending during that time.
@Keffertje
On your theory, nobody knows, but the experts such as SimonG say any depressure most likely happened at IGARI. Not sure why they say that.
As far as FMT, if I understand from Helios some equipment may actually overheat due to less cooling from the air fans with the low density air, like a PC fan. Keep in mind, the cooling upon depressure is transient we are just saying the air itself gets cold due to the ideal gas laws and adiabatic expansion (it is not due to outside cold air coming in). Everything else in the plane is at room temp, unless the pilot is trying to freeze everyone with cold air conditioning, that’s a different story.
One comment said O2 mask drop-down could be stopped by cutting off the altitude meter circuit so maybe the pilot re-powered that circuit or something like that at SDU reboot. Re: SDU maybe the pilot was concerned about equipment overheating if he was depressured, and he felt he needed to come back up to normal air at just before FMT.
I would like to know if depressuring causes cloud contrail formation, and if so we could look for it in the satellite images. I am still confused if the satellite cloud contrail photos at FMT, which seems to clearly show FMT, are considered valid.
@Jeff – you state “but no one has every come up with a very compelling story as to what that piece of equipment might be…”
Ironically *you* have previously facilitated and communicated a compelling explanation for this – refer May 16 post (The SDU Re-logo, a small detail..) and prior.
Specifically, I’m referring to the electronic cockpit door lock as powered from the left AC bus.
Yet again I’m inclined to (re)post the following proposed end-to-end scenario which slots this possibility nicely into step [d].
I wonder about your warming to this scenario since dismissing it long ago (pre-debris).
—–
a) Zaharie hijacks from the cockpit after locking Fariq out (both with electronic and physical cockpit door lock)
b) Z commences depressurization of cabin, utilizing flight deck oxygen for himself
c) Pax succumb, Fariq and/or other crew scramble to portable emergency oxygen so have about ~1 hour (?)
d) In desperation (after failed attempts at cockpit door) Fariq and/or crew access EE bay and flick left AC bus breakers in trying to disable electronic lock. This coincides with 18:25 satcom reboot.
e) Physical lock in place, so still no access. Desperation escalates, and not knowing Z’s intention (maybe suspecting suicidal / homicidal attacks), Fariq(?) re-enters EE bay to also disable the flight deck oxygen supply tanks.
f) Z succumbs to no oxygen. Soon after, and with no access to cockpit, Fariq / crew portable bottles run out, and they too loose consciousness.
g) This occurred after Banda Aceh turn but before Z’s intention to subsequently turn back to KL for potentially nefarious reasons
h) Thus, with everyone on board deceased, ghost flight continues on last known leg direction, to SIO, until fuel exhaustion.
@Enzyme, I think that’s about as good a Zaharie-suicide scenario as you’re going to get. A couple of problems (and every scenario is going to have problems: 1) Fariq would have no idea that the door lock was on the left AC bus, and if he did go into the E/E bay to disable it, and knew what he was doing, he’d just pull the circuit breaker. And why would the SDU re-boot? Some people have proposed that he went into the E/E bay and just randomly pushed and pulled circuit breakers, but I don’t think any pilot would do this. 2) You still wind up with a ghost flight scenario, which has essentially been ruled out.
Why didn’t he just strike into something in KL on route over My from IGARI rather turn back from Banda Aceh as he had Fariq out of flight deck if he was suicidal with a mission to damage as well??
Everything that happened was made to keep us guessing and never figuring out. So much that what needed to happen was meant to never be known.
@TBill I,e Simon F$*%h???Gynson is NO expert as he,claims to be. HE trolls articles relating to MH370 claiming and dictating with arrogance that he knows what happened. If you put fourth your opinion/theory that does not match his criteria.He gets very agitated. Actually his wild theory that MH370 DID not turn back and fly over the Malacca straight but flew directly over mainland Indonesia to end deep in the SIO due electrical fire is the most outrageous stupid theory. For one faceted. How would Indonesian military radar not detect that? But he claims both the Malaysian and Thai military was wrong. So don’t call the crack pot an expert!!
@Jeff – I think very desperate circumstances might indeed lead to random manipulation of circuit breakers. Re pulling circuit breaker vs overall left bus – I’m not sure what the specifics of the EE bay are, but perhaps certain aspects of layout or wiring explain choice of bus over breaker? Further, are all breakers in the EE bay, or are some in the cockpit?
@MH – I had in mind that ‘lingering’ (e.g. allowing turn back from Banda Aceh) might have allowed room for (failed) negotiations or perhaps some other form of general indecisiveness.
@Jeff
you wrote:
“@DennisW, You wrote, “The BFO data is perfectly valid.” But why do you say that? Because you feel it? If the passion of one convictions were our only gauge of truth we would still be making sacrifices to appease the gods. If on the other hand you can demonstrate that the deliberate alteration of BFO values is impossible, please do it.”
Starting backwards from your questions above. It is difficult to prove that something is impossible so I will put that query in the domain of the rhetorical.
The reason I say the BFO values are valid is that they conform to the known physics governing oscillator behavior. There has been a lot of history on this blog relating to that. As you may recall there has been more than one animated discussion I have had with ALSM on that topic. Discussions which almost got me banned back in the day when ALSM had “golden boy” status. BTW, do not interpret that remark as negative relative to ALSM. I have a very high regard for him.
There has been and is a persistent failure to understand oscillator behavior among the ATSB, IG, DSTG, and other respected individual contributors. When the DSTG computes a variance on the BFO drift (as they did in their book) everyone assumes that if one were to sample the oscillator drift one would get a gaussian distribution of errors. The reality is very different. With respect to oscillators the use of the term variance refers to an ensemble of trials which indeed are likely to exhibit zero mean, with a calculable variance (a variance which is not static, BTW, but grows over time). It does not refer to the distribution of errors one would expect over the course of a single trial. The result of any one trial will exhibit a random walk that departs from zero and generally continues to increase the deviation from zero as time goes on. When DrB decries that some path shows a one-sided deviation in BFO errors, I cringe. I cringe because that is exactly the behavior one would expect.
I will write up a description of this behavior on the site on normally use for MH370 illustrations, and hopefully that may make things more clear. It may be a few days.
I still don’t understand why a FMT after 18:40 requires loitering or what kind of loitering that is.
In their first report (June/August 2014), the ATSB came up with a number of flight paths that disregard the 18:40 phone call as evidence for a southerly route by that time. They seem to have preferred the assumption “initial track takes a northern hook around the tip of Sumatra”. I think that would fit well with further assumptions, such as a turn towards the north between 18:22 and 18:25, avoidance of Indonesian radar and drift studies pointing towards the Broken Ridge area (p. 26f.):
http://www.atsb.gov.au/media/5243942/ae-2014-054_mh370_-_definition_of_underwater_search_areas_18aug2014.pdf
@Enzyme
“b) Z commences depressurization of cabin, utilizing flight deck oxygen for himself”
As I just tried to explain, it does not work like this.
Reinhold Messner climbed Everest without supplemental oxygen – that is over 29,000 feet. With oxygen, he would simply have climbed it more easily. Now very few of us are as fit as he was and most of us would suffer to a greater or lesser extent, simply being at 29,000 feet – but, only the weak/ill/elderly would actually die. Some others might pass out but they would revive at lower altitude or with an oxygen bottle. At 25,000 feet, there is insufficient oxygen for most people to behave normally but not so little as to cause hypoxia – the average person would survive.
Above that altitude, there is a point at which nobody could survive because the body cannot absorb the available oxygen (whether it is oxygen in the air or from a bottle). The only way to survive is with pressurised breathing apparatus – the pressure is as important as the oxygen, the pressure allows the lungs to exhaust CO2 and absorb oxygen – at very low pressure, lungs do not work.
If a plane is high enough to kill the average person through hypoxia, then everyone dies. No amount of oxygen bottles in the cabin will save the pilot – he dies too, as there is no way to get the oxygen from the bottle into his blood. His lungs cannot do it as the atmospheric pressure is simply too low; as he descends he will reach a point where his lungs will start working again – only at that point are oxygen bottles useful.
Around 35,000 feet only someone with pressurised breathing apparatus can survive. This is not a question of oxygen bottles it is how the body works.
@PaulC
Ok, but I think it is important to note that MH370 was flying at around 30,000 ft during that critical stage:
https://www.atsb.gov.au/newsroom/correcting-records/inaccuracies-in-reporting-on-the-search-for-mh370/
It was at 35.000 at IGARI but thereafter steadily descending. It most likely was pressurised at least until that point of time (and the rest is conjecture) and it would take several minutes to bring cabin pressure to a critical state if the outflow valves were opened. If something catastrophic happenend, such as rapid decompression, it would be different, however.
@Enzyme – I am not so sure about negotiating since the PAX were already dead before the “loitering” so what sort of bargaining angle ZS would have? The loitering maybe wrongly used for the SIO.
@DennisW
“When DrB decries that some path shows a one-sided deviation in BFO errors, I cringe. I cringe because that is exactly the behavior one would expect.”
Are you suggesting / saying that DrB may have found GOOD candidate paths, but he has falsely rejected them BECAUSE he thought the one-sided BFO errors are wrong, and you think they are correct ?
If so, did you tell him, and explain why ?
@Nederland
Thanks for the reply. I understand what you are saying but my point is that either everyone survived, or, everyone died. Any suggestion that all the passengers were murdered but those with oxygen bottles survived, is a non-starter. If people were dying the only way to survive was with special breathing apparatus.
This site will tell you more than you probably wanted to know: http://www.pilotfriend.com/aeromed/medical/alt_phys.htm
@DennisW, I usually grab a nice beer, put my feet up and read your posts:) and G’s where my oscillation varies between fits of laughter and tears of sadness. Now I have to go read up on Gaussean and distribution of errors. Thanks!!
@DennisW, One would expect the data to have this same realistic appearance if it were generated by the same equipment — satellite, plane, SDU — but with erroneous terms fed into the Doppler precompensation algorithm, would it not?
@Jeff Jeff, let me try this again if I may. I would really like to hear your response:
Posted September 25, 2016 at 11:33 PM
@Jeff As I understand things, this is the first time anyone has used BFO data to recover a flight path. So the ‘perpetrators’ not only know how to modify the SDU but they also anticipated (apparently with some certainty) that these values would be used in this manner.
How many people could have made such a prediction? Surely that must begin to characterize the perpetrators..
@Shadynuk, Sorry, I thought I was answering your question but directed it to @Keffertje by mistake. What I wrote was:
“Victor and Gerry Soejatman looked into the question of who might have had the technical chops to spoof BFO data, and came up with a short list that included the US, Israel and Russia. Note that four months after MH370 another Malaysia Airlines 777-200ER was downed in an operation run by Russia’s GRU (military intelligence).”
@all
https://davidlearmount.com/2016/09/25/mh370-search-to-stop-just-short-of-hardys-predicted-position/
See also Hardy’s YouTube explanation, which was instructive for me.
Coincidentally, Hardy’s route is very similar to the route if you forget about the INMARSAT arcs, and just assume the pilot went down the NinetyEast mountain ridge. So my final change would be a turn over to Broken Ridge.
At the moment, I am collecting route logic theories, so Hardy’s is one I missed.
Question- Why do we need to assume empty fuel tanks, if the target was x,y he could just put the nose in right there?
Note the crowd funding proposal.
@jeff @Shadynuk
right after when “another Malaysia Airlines 777-200ER was downed in an operation run by Russia’s GRU (military intelligence).” it was suspiciously reported that Rajik was in communications with the rebels on “Secure Diplomatic Channels”… just wondering since when do rebels/terrorist have “Secure Diplomatic Channels” ?? It must be Malaysia and Russia GRU spoke directly to each other.
@Aaron
Thank you for the insight. Actually my adopted expert theory is Ewan Wilson in the book Goodnight Malaysian 370. I just noticed SimonG seems to be on the same page as far as where a depressure may have happened. As far as final route I am going with the ocean mountain expert comments Peter Lee’s book. Just a starting position for me.
@PaulC
Thank you for that link. This is instructive. It sets to 34,000 ft the level above which positive pressure is required. I have found slightly different limits in other sources.
So, do you mean literally everyone on board the flight, including whoever was in the cockpit? The FI does not say that the cockpit oxygen masks are pressurised breathing apparatus. Does that mean whoever was in the cockpit would have died along with the others?
On the other hand, MH370 was quite probably flying below 34,000 ft and oxygen for passengers would have lasted 22 min, for flight attendants 75-110 mins, for flight crew well above that. Unlike passenger masks, portable bottles allow individual oxygen flow.
@Jeff Thanks. I am quite certain that there are people outside those three countries who have the technical knowledge. That could make for a very long short list!
Not to belabor the point, but it is not so much the technical ability that is remarkable to me, it is the prediction that the BFO data would play such a crucial role in setting the search area. If I were a suspicious person my first guess would be that someone who was a party to suggesting the use of the BFO data to help resolve the North/South ambiguity of the BTO data, was also a party to altering the data.
(I believe it is true that the BFO data essentially resolved the North/South ambiguity of the BTO data – perhaps that is not true.)
Also, is it not possible that this data could have been altered ‘after the fact’; that is, altered as it resided on some Inmarsat database somewhere? That does not change the fundamental premise, but it may change how an investigation is done.
@depressurization:
So a follow-up question must be: Could the pilot/s possibly have depressurized the cabin (except the cockpit) without noticing it, by mistake, already before Igari, and then hesitated about what to do before he/they finally decided to go down with the aircraft in an area at least one of the pilots knew from playing with his flight-sim?
And about the satellite image of contrails around FMT, was there really something like that? No?
@F4
“I think it is close to a fact, that they were unconscious or dead by that time, in any scenario, technical, suicide, political, you name it. We have no activity from the cabin what so ever. Explain why?”
Happy to.
I think the chandelle is a radar error due to the large slant range. If you look at the original plot in FI, the final outbound heading mates up almost perfect with the resumption of primary tracking on the return heading if the plane made a 25 degree bank turn with a 15nm diameter at 1.2 Gs.
It’s pitch black. Not a single passenger perceives the turn as anything more than normal navigation. All they know is that their IFE goes out, for which a pilot gets on the PA and apologizes.
They spend the next 6.5 hours flying along quietly until they notice it’s dawn and they’re over the ocean, which is weird. By that time it doesn’t matter because very soon they’ll be in a VNE+ dive for the water.
Yes. My version of the events is rather simple. Sorry about that.
@Johan,
No you can’t depressurise the cabin separately from the cockpit.
@Nederland
“…do you mean literally everyone on board the flight, including whoever was in the cockpit?”- yes!
Oxygen bottles are only of use if the atmospheric pressure is high enough to permit breathing. To ensure that the passengers were dead, rather than just unconscious, whoever was in control would have had to ascend to an altitude where normal breathing was physiologically impossible and they could only have done this (and lived) if they had pressurised breathing apparatus for themselves. At that altitude, simple oxygen bottles would have been completely useless.
If there was a depressurisation event that killed all the passengers, then ALL on board died – unless they had access to pressurised breathing equipment.
@Shadynuk, You wrote, “(I believe it is true that the BFO data essentially resolved the North/South ambiguity of the BTO data – perhaps that is not true.)” To put this in stronger terms, before the discovery of the Réunion flaperon, the BFO data was the only evidence — the only evidence! — that the plane went into the southern Indian Ocean.
@Nederland:
Well, thanks. It seems it will be difficult to harmonize all aspect in any event.
@PaulC
I think this is interesting.
There is also evidence to suggest that both pilots were smokers. If Zaharie, for example, was still smoking in his early fifties, I think that pretty much rules him out as the possible author of the deliberate depressurisation scenario as prolonged smoking is the number one risk factor in assessing individual resistance to high altitude exposure.
You probably also had to answer questions if you carry your pressurised breathing equipment in your hand luggage. That would barely go unnoticed in follow up investigations either.
So, perhaps best to bin the deliberate depressurisation scenario?
@Nederland
I do not know whether it is “best to bin the deliberate depressurisation scenario” or not. It remains possible but not as currently suggested.
It would not have been a simple matter and anyone wishing to pursue this idea needs to explain how it might have been accomplished – leaving at least somebody still alive.
Jeff states above: “[the] ghost flight scenario, …has essentially been ruled out” – so if anyone was still alive, perhaps everyone was still alive (unless they were incapacitated in some other way).
A number of theories rely on the passengers being dead – if they were not dead how would that change things?
@Paul C
Flght crew masks are FAA certified up to 40,000 feet, as are the drop down passenger masks and neither deliver pressurized O2. In fact, the FAA only requires pressurized delivery ABOVE FL400.
I personally have flown 4 hrs at FL220 on a cannula. It’s was illegal, but my pulse ox meter never went below 92 the whole time. And that’s a cannula where a good 1/2 of the air you’re breathing is natural air.
I guess what I’m saying is I don’t have a clue what you’re talking about.
@Matt Moriarty
I’d say, but I may be wrong, that they are safe if you descend from that altitude as quick as you can. You would not normally continue to fly on that altitude for a few hours.
@Jeff “…… so what did you understand had been planned? Who is the businessman, what was your connection to him, and what was his connection to this plot? The more detail you can provide, the more value your information will have ……”
Jeff, I’m sorry I can’t answer some of your questions for reasons of personal safety.
He did not know what actually happened to MH370 but he did know what was planned to happen.
He was quite categorical that Shah had no intention of committing suicide. Shah’s intention was to ensure the plane landed safely.
Details of the plan and implications as I see them were outlined in a score or so postings on this blog back in May this year.
Sorry for not being an expert myself so I have more questions than answers..I see that some of the theories put forward in posts involve a pilot influencing the flight from the e/e bay. Could anyone please explain if it is part of professional pilots’ training to be able to understand how the e/e bay works ? Would most pilots be expected to have devent k’owledge of this? Thanks!
@ Nederland
The reason you descend is because of the finite capacity of the 02 tanks and the 110 minute supply rule at 10,000′ for the flight crew. The advent of quick don masks for pilots removed the old FL250 restriction and now allows the PF to stay off the mask “at or below FL410.”
Part 121.333
@MH @JeffWise
Was there ever a definitive debunking or conclusion to the Beshtash Valley theory? I.e., did anyone ever travel to the site to examine for debris?
Apologies if I missed this in a previous thread.
@Matt Moriaty
So, “at or below FL410” means in a pressurised cockpit? The FI says crew oxygen supply would last for 13 hours (for two pilots) at 36.000 ft (unpressurised), why is it then required to do an immediate emergency descent?
@Jeff
“@DennisW, One would expect the data to have this same realistic appearance if it were generated by the same equipment — satellite, plane, SDU — but with erroneous terms fed into the Doppler precompensation algorithm, would it not?”
I don’t know of any way to tell if the data is spoofed just by looking at it. I am assuming a good spoof here. Not some random garbage.
@PaulC
The ghost flight is still possible if MH370 was descending at 18:40 rather than flying south. That seems to be Neil Gordon’s assumption of what happened.
So I’d say depressurisation occurred either after the FMT or not all.
Passengers would likely try to fight back or to find some way into the cockpit imo.
The portable ELT could have been removed at some point before or during the flight.
It has only been reported (by CNN) that there is no record for registered calls from mobile phones from the aircraft. A possible explanation is the plane was too fast or too high up. For example, the co-pilot seems to have switched on his phone again and may therefore have tried to call someone, but didn’t succeed. At least one other news article seems to suggest that other mobile phones connected as well. There was little chance to connect to a tower once MH370 had cleared Penang.
A question from about 2 years ago. (Initially, I had sent this privately to Dr. Ulich who replied with a valid explanation.) However, based on the subject of this thread, I am asking everyone:
If the FFB is a “fudge” factor to get the BFO at a known location to match the measured amount, is there a reason why this value is fixed rather than being proportional or variable?
For example, years ago I purchased low profile radial ply tires to replace the bias belted tires on my car. I soon noticed these smaller diameter tires caused a speedometer error. 3000 rpm on the original tires indicated 60mph and was reasonably accurate. With the new tires, 3000 rpm still indicated 60mph but the true speed was about 54mph. Therefore, the speed offset was 6mph. At 1500rpm the actual speed was not the same fixed 6mph offset but 3mph. i.e. It was not 30-6=24 but rather 1500/3000*54=27mph or a proportional offset. Any reason that the “fudge” factor for all of the BFO errors is a fixed value.
@MP, No, pilots would not be expected to know how the E/E bay works, and some airlines explicitly forbid their pilots from going down in there. It’s sort of how like Apple doesn’t want you opening up the iPhone and tinkering with it.
I don’t recall if it was explicitly debunked but I think it’s rather far from the seventh arc. Of course once the BFO values came out everyone stopped talking about that sort of thing.
@DennisW, If you’re acknowledging that it is indeed possible that the BFO data could have been spoofed, I think that’s a significant area of agreement.
If forensic examination of the debris shows that it did not arrive at its discovery locations naturally — and I’m just saying “if” at this point — then this will become important.
@Lauren H
Perhaps to many “predictions of accuracy” creating everyone’s differentials. lol.
@Matt Moriarty
At FL220 you have 0.46 atm and blood saturation is 60%. Without oxygen, you might feel a bit short of breath but assuming you are reasonably healthy, you can stay there pretty much indefinitely. If you have to have your wits about you, then additional oxygen, to get your saturation back up to 96-98%, is achieved through a simple continuous flow system; nobody will die at 22,000 feet.
At 40,000 feet, air pressure is 0.19 atm and (un-pressurised) blood saturation is 0%. this is because the lungs cannot exchange O2 and CO2 at pressures of less than 0.2-0.25 atm.
You are right that the FAA regulations require certification to 40,000 feet but that is for emergency use and is easily achieved by slight pressure in the oxygen flow through the regulator. This is why the mask must fit quite tightly and why beards/moustaches are a hindrance.
I don’t see how this changes anything. Either everyone lives, or, everyone dies. For extended flying at or above 40,000 feet, a positive demand regulator is essential. At 40,000 feet, your cannula would simply not help you as you would be unable to make use of the oxygen due to the low pressure.
@Matt Moriarty
“It’s pitch black. Not a single passenger perceives the turn as anything more than normal navigation. All they know is that their IFE goes out, for which a pilot gets on the PA and apologizes.
They spend the next 6.5 hours flying along quietly until they notice it’s dawn and they’re over the ocean, which is weird. By that time”
No, it would not happen that way. But you are free to believe otherwise.
@PaulC
You are wrong on the O2 system. The cockpit crew oxygen system is different from the cabin system. Some parts from the manual.
OXYGEN SYSTEM CREW OXYGEN
B 777 35-11
Normally you breathe a mixture of oxygen and compartment air when you set the oxygen dilution control to N (normal). The percent of oxygen has a relation to the pressure altitude in the flight deck. At or above a preset pressure altitude the regulator gives you 100 percent oxygen. You breathe only oxygen at any pressure altitude when you set the dilution control to 100 percent.
Normally, oxygen flows only when you breathe (on demand). The flow indicator shows flow each time you breathe. If you set the emergency demand control to emergency, oxygen will flow continuously (pressure breathing). The flow indicator shows continuous flow.
The vent valve (not shown) is part of the mask. The valve lets air and oxygen flow from the mask into the goggles (not shown).