UPDATED: See end for description of possible northern route
On Saturday, March 15, Malaysian authorities released an analysis of satellite data that dramatically narrowed the possibilities for where missing Malaysia Airlines Flight 370 had gone after it disappeared from radar on March 8. Over the course of the following week, Inmarsat released further information that not only showed where the plane went, but also indicated how it got there. The results are shown on this chart. We still don’t know if the plane headed north or south, but if it went north, it made landfall near the western India-Bangladesh border and proceeded along the Himalayas to Central Asia. If it went south, it passed over western Indonesia and out over the southern Indian Ocean.
How are we able to determine this? The procedure requires a bit of explanation. Inmarsat is a communications satellite in geosynchronous orbit over the Indian ocean. That means it remains in the same place in the sky, like it’s sitting on top of an invisible pole. Because it’s so high up, it has a straight line-of-sight to virtually the entire eastern hemisphere. That’s great for radio communications: if you can see it, you can send it a message, and it can send that message along to anyone else in the eastern hemisphere, or to a base station that can then relay it to anywhere in the whole world.
Every hour, Inmarsat sends out a short electronic message to subscribers that says, “Hey, are you out there?” The message contains no information as such; the satellite just wants to find out if that particular subscriber is out there in case it wants to talk. Kind of like picking up your telephone just to see if there’s a dial tone. On the morning of Saturday, March 8, MH370 replied seven times to these pings, saying, in effect, “Yup, I’m here.” The line was open for the plane to communicate with the outside world. But the system that generates the messages themselves, called ACARS, had been shut off. So nothing else was communicated between the satellite and the plane.
All the same, those pings tell us something important about MH370: they allow us to narrow down its location. Because light travels at a certain speed, and electronics take a certain amount of time to generate a signal, there’s always a length of time between the satellite’s “Hey!” and the airplane’s “Yo!” The further away the plane is, the longer it takes to say “Yo!,” because it has to wait for the signal from the satellite to travel that extra distance.
Imagine you and I are in a darkened room. You have no idea where I am, except you know that I’m holding one end of a taut, 20-foot rope, and you’re holding the other. Therefore I must be 20 feet away. You don’t know where I am, exactly, but you know that I must like somewhere along a circle that’s 20 feet in radius, with you at the center:
Now, it happens that in this room there are walls and pieces of furniture, so you’re able to rule out certain spots based on that, so instead of a whole circle, you have pieces of circle, or arcs.
MH370 was in an analogous situation. When Inmarsat pinged it at 8.11am, the amount of time it took the plane to reply allow us to calculate its distance from the satellite, just as if it was holding a taut piece of string. Instead of furniture, factors such as speed and fuel capacity provide other limitations of where it could be, so its range of possible locations is also not a circle but a series of arcs:
Note that these arcs do not represent the path that the plane took, but the range of possible locations at 8.11am. That particular ping tells us nothing at all about how the plane got to wherever it happened to be. So at this point all we know is where it started (it disappeared from Malaysian military radar at 2.15am at a spot between the Malay Peninsula and the Andaman Islands) and where it ended up. It could have taken any of a zillion routes to get from its start point to to its final recorded location somewhere on that last arc.
Remember, however, that Inmarsat received six earlier pings as well, and from them we can narrow down the range of possibilities dramatically. The first was received at 2.11am, just before MH370 disappeared from Malaysian military. Its length indicates that the plane must have been somewhere on the green circle at that moment:
Of course, thanks to radar we happen to know in this case pretty much where the plane really was at this time — around the area of the pink dot.
On Friday, March 21, an Inmarsat spokesman told me that “the ping timings got longer,” meaning that the distance between MH370 and the satellite grew increasingly bigger, and never smaller. That means that at no point during its subsequent travels did MH370 travel any closer to Inmarsat. So from the 2.11am ping data alone, we can rule out every spot within the green arc:
MH370 never traveled anywhere in the shaded area. (Of if it did, didn’t stay there for long; by the end of the hour it had to be outside.) We also know that it never was further away from the satellite than it was at 8.11am, so we can exclude everything east of that, as well. Finally, we can rule out some chunks close to its starting point for other reasons:
So just from the 2.11am and the 8.11am pings, we know that MH370’s route of flight must lie within either of these two broad swaths — one lying to the north, and the other to the south. Bear in mind, the reasoning that we’ve just gone through doesn’t tell us anything about whether the plane went to the north or two the south. Because of the symmetry of a circle, the possible paths are mirror images of one another. However, we’ve vastly reduced the range of flight routes that MH370 could have taken. For instance, a popular theory circulating on the internet posits that MH370 tucked in close behind a Singapore Airlines flight, “SIA68,” in order to hide in its radar shadow:
This new Inmarsat data rules out that possibility. It also rules out the idea that MH370 flew south through the middle of the Indian Ocean to avoid military radar. If the flight went south, it would have had to have gone through Indonesian radar coverage.
Interestingly, on March 19, the website Antara News reported that “Indonesian Defense Minister Purnomo Yusgiantoro said the Indonesian military radar placed in the country’s western-most city of Sabang did not detect an airplane flying over Indonesian territory.”
On March 22, 2014, CNN reported that China, India, Pakistan, Myanmar, Laos, Kyrgyzstan and Kazakhstan have told investigators that “based on preliminary information, their nations had no radar sightings of missing jetliner.”
So far, we haven’t talked about what we can deduce from the remaining five Inmarsat pings, the ones received at 3.11, 4.11, 5.11, 6.11, and 7.11. It should be possible, based on the presumed speed of the plane and the distance between the successive arcs, to make some reasoned guesses about how the plane traveled from one to the other. I haven’t seen the data yet—I’m working on it—but earlier this week the Washington Post published a map that showed what appeared to be the results of just such analysis as applied to the southern route, carried out by the NTSB:
This appears to be why the nations assisting the investigation have poured so many assets into searching that particular stretch of southern ocean. If MH370 took the southern route, it would have had nowhere to land, so it must have crashed and its debris must still be floating somewhere in this area.
Of course, the information we glean from Inmarsat data about MH370’s flight route is, by itself, symmetrical around an axis that runs from the spot on the ground underneath Inmarsat to the point where the aircraft was last observed. So assuming that the NTSB’s interpretation of the southern route was only based on factors of speed and arc spacing, it should be applicable in mirror form to the northern route as well. I’m working on that right now.
UPDATED 3-23-14: Okay, I feel a little slow on the uptake on this one, but it turns out that if you flip the NTSB’s guesstimated southern route, you come up with a northern route that looks pretty much like this one published in the Daily Mail (I know, I know):
Basically, you make landfall in the vicinity of Bangladesh, skirt along the border between India and Nepal, then cut across northeastern Pakistan and Afghanistan before winding up in Uzbekistan or Kazakhstan. This may be why Malaysia recently asked Kazakhstan if it could set up a search center there.
Kazakhstan would not be a bad place to try to hide an airplane. It is larger than Western Europe with a population of just 17.7 million. Its expansive, sparsely populated steppe and desert terrain make it perfectly suited as a touchdown spot for Soyuz space capsules. The country gained independence from the Soviet Union in 1991 but its communist-era ruler, Nursultan Nazarbayev, remains in power. He is a close ally of Putin, and two days after MH370 disappeared told the Russian premier “that he understands the logic of Russia’s actions in Ukraine,” according to Reuters.
I said above that inmarsat proved the plane was near the southern arc – but there are assumptions for altitude and speed. Well there is one more piece of data we have that helps with the assumptions. They know how much fuel was in the plane (unless you believe someone on ground is complicit to add more). We also know the plane was flying 7+ hrs after take off. Unless you believe it landed and took off in between there – to fly 7+ hours straight on the fuel it had, it needs to be at approx normal altitude (35,000 etc). So even though it descended to 12000 it climbed back up (likely on autopilot with zombie crew). So the only unknown is the speed. So if it flew for 7+ hours at unknown speed not necessarily in a straight line – again could be anywhere along the south arc – but if straight line and normal speed – its where they say it is
Guys, before some of us go into conspiracy mode and assume there’s something basically wrong with the caluculations, think about it: We don’t have the necessary COMPLETE data nor the qualifications to make an informed judgement. All, we can do at the moment, is, trying to understand, if their arguments are sound in principle. I read Jeff’s last tweet. Apparently he is going over the recap provided for journos with an expert, who, at least for now, declared, that it adds up. I think, we can safely assume, the plane crashed into the Indian Ocean somewhere along the Southern arc after 08:19 am. There are margins of error due to the assumptions about speed,hight and possible deviations, the plane might’ve made from a linear direction. Maybe, there are still surprises in store. But I’m ok with the statement, the the plane crashed into the ocean somewhere along the Southern arc.
Of course, these calculations need to be peer reviewed as soon as possible. They have to open up.
@airlandseaman where did you find that data about what the AAIB gave to investigation team?
Has anyone seen a cogent explanation of how the inmarsat data was analysed to show that it went south? All the doppler effect can show is whether at the time of the ping the plane was moving closer to or further from the satellite, correct? If the plane was changing headings and/or speed how do you eliminate the northern route. I’m not trying to push any particular theory, just curious.
If the pilot did,if fact, turn the jet in order to make an emergency landing, why didn’t he land it? This leads me to ponder, if someone wanted (for some unknown reason) crash a jet so that it would never be found, then what better place than the South Indian Ocean? Maybe that was quite simply the intention all along.
@JJinJupiter, read the report in The Malaysian Online. I posted the link today at 10:19 am.
This last and final “partial” ping is VERY intriguing. I would assume a ping at 0019 GMT would be unscheduled. Does it not stand to reason that because this was an “unscheduled” ping (and with the assumption the ONLY unscheduled ping), that everything was mechanically working on the plane until 0019?
I don’t understand how the analysis of the “earth shape” effects resolves the north/south ambiguity.
From INFORMATION PROVIDED TO MH370 INVESTIGATION BY UK AIR ACCIDENTS INVESTIGATION BRANCH (AAIB): “The Inmarsat technique analyses the difference between the frequency that the ground station expects to receive and that actually measured. This difference is the result of the Doppler effect and is known as the Burst Frequency Offset.”
Its “MH370: Burst Frequency Offset Analysis (450 knots)” attachment shows maximum north-south difference of around 90hz, with the correlating with the expected.
Consider a simple model of Doppler shift:
K * speed_over_ground * cosine(angle_off_the_perpendicular_COP) + …
The constant K includes the net effects of the angle off the satellite’s perpendicular and curvature of the earth’s surface to the circle of position, as well as an assumed a satellite communications frequency of 1.6ghz. A rough calculation shows K to be 1hz/mph.
With a 500mph track perpendicular to the derived circle of position (COP), the doppler shift would be around 500hz.
Changing my expectation to 300mph at 70 degrees off the perpendicular gives 103hz. But how did I come up with that course and speed?
This begs the question: How would the southerly conclusion based correlations of the actuals to the expected hold up with materially different set of course and speed expectations?
@littlefoot: I tried the link and it didn’t work. Is that link still live?
@Lee Schelinger @airlandseaman
The Inmarsat Doppler analysis to determine a N-S orientation (which is the only thing the the Times mentions today as leading to the Malaysian announcement) is untrustworthy because it will rely on faint second and third order effects in the response signal that are not fully understood theoretically. Inmarsat developed an alogrithm which they applied to known data from the past. It seemed to work.So they applied it to 370 and concluded that it was heading South. It’s too emperical and very questionable. It’s a first time effort.
(I am a mathematical physicist with no experience in this area, but I do know how reasonable but false assumptions can get you in a lot of trouble.)
It was great to see Jeff being given some real time without interuption on CNN this morning. He made the essential point that Inmarsat must share their analysis with other scientists for review and criticism if it is to be taken seriously.
@Littlefoot: I think this is the link you menat to share http://www.themalaymailonline.com/what-you-think/article/information-provided-to-mh370-investigation-by-uk-aaib
@JJinjupiter, yes, that’s the one. Did I make a mistake with the link? Thanks a lot for correcting it! I typed it into my mini tab. Sometimes it ‘swallows’ bits and pieces, very annoying. Good, that you found it anyway.
Unfortunately, we can’t correct our own posts here. But I hope, everybody here is clever enough to find it anyway.
@ Littlefoot :
Understood. But think back over the life of this story/investigation, and ask how many of the ‘facts ‘ which were made public during the first week still survive… yes, MH370 took off from KL with a flight-plan direct to Beijing. What other ‘facts’ are still ‘facts?’
Was there an ascent to 45 K feet?… followed by a 23 K descent within a minute down to 22K?… And did it hit those waypoints over the Strait of Malacca?
CNN got it from an “unnamed source close to the investigation” that it had flown for a while at 12 K feet… And why is that item so sensitive that this ‘source’ couldn’t identify himself?
And yesterday the Malay PM himself tells the world the flight ended in the So. Indian Ocean… with all souls lost … without even one piece of debris positively identified as being from MH370 or any Malaysian plane or any 777 found yet?
Family-members of passengers are rightfully suspicious… you also would be.
This ‘investigation’ smells. It’s not just that the Malays were out of their element to begin with…from what you guys are saying it sounds like Inmarsat has ‘massaged’ some of their data, has maybe employed some smoke and mirrors.
I’m not suggesting this IS what happened, but i’ll suggest it COULD have happened : Lets say MH370 went off-course due to either hijacking/commandeering/mech-failure/fire, wandered into some country’s sensitive airspace, got shot out of the sky, that country realized what happened, people at the highest levels of that government, and the Malay government, and Malay Air huddled together to put together a story of how something else happened, and needed even Inmarsat to cook up something scientific to help sell it.
Wars were started because the Maine blew up in Havana harbor, because a driver in Sarajevo in 1914 took a wrong turn enabling a failed assassination plot to succeed… Could governments conspire to cover up an accidential airliner shoot-down… and perhaps years from now the true story gets told….
It’s come to light lately that PanAM/Lockerbie was not planned by Libya but was planned by Iran, as pay-back for the US Navy’s shoot down of that Iranian airliner off Bander Abass.
Blow-back… no one wants it. So just pretend, for a bit, that some country accidently, mistakenly, shot down MH370. Would their governments let the real story come out, let their populations get in frenzy, or, would their governments attempt to cover it up, sweep it under the rug? I can’t answer that either… but not out of the realm of possiblilty.
@GWiz, I think, the only solution to this conundrum is, as Arthur T mentioned as well, that everything gets published and peer reviewed. Otherwise,as long as no debris from the plane is found, these findings won’t be readily accepted.
Let’s be clear here. The north and south arcs as they have come to be known are an urban legend. There is one continuous 08:11 circle, and the aircraft may or may not have crashed or landed sometime around 08:11, somewhere near that circle, including the possibility of due east of Malaysia. It all depends on the speed assumption. If the speed was 200 kts, it went east, not south or north.
@WhereInTheWorld, the last, incomplete ping was at 08:19 am Malaysian time. Jeff corrected me. It was the very last incomplete communication with the plane.
@airlandseaman, my link to the report wasn’t correct. JJinjupiter gave the working link at 02:57 pm.
I hope that in any case something of the plane is found. If not then questions will remain for days, weeks, months and years. For many it will be a curiosity solved either by reason and logic supported by math or imagined scenarios supported by conjecture. For the families of the passengers they will not be a questions of curiosity, but rather haunting questions that never leave them.
While I agree that there are multiple flight paths that could be constructed that would fit the satellite data, they are not infinite. The aircraft has both a minimum and maximum speed. Given that the time/return data and the doppler data match a relatively few southerly straight line routes south at normal cruising speeds, it seems reasonable to assume that the aircraft followed one of them.
Could the plane have flown S shaped patterns and hit the “ping” points at just the right time, speed and angle to match the data? Sure, it’s possible.
But it is more practical to focus on searching areas suggested by straight line flight at normal cruising speed. Resource deployment should follow the most probable scenarios.
@Littlefoot, I do understand that the final “incomplete” ping was 0019GMT/0819 Malaysia time. My question is that if all of the other pings were scheduled, and were happening at 11 minutes after the hour, then this one was perhaps a final “catastrophic” ping. If there was some sort of mechanical malfunction, then wouldn’t that support, though not prove, that there was no earlier mechanical malfunction hours earlier when the plane took its initial turn off course? Essentially, if there was some mechanical malfunction early on, why aren’t there unscheduled pings from early on too???
@WhereInTheWorld, the extra incomplete ping has hit some of the bigger media outlets now (BBC, The Telegraph), and your thoughts are indeed endorsed by some sources.This ping at 08:19 could indicate the final catastrophic event. If, true, that would be huge. You could pinpoint the time of the final crash pretty exactly. But I guess, it’s too early to draw such a conclusion. I’m sure, we will hear more about it soon. At the moment they are still investigating this event.
I would like to know if I am understanding correctly. Earlier today someone explained the plotting of the pings using a slinky as an analogy. So the distance to each arc is based on how expanded or contracted the slinky is. And the amount of vibration in the slinky determines whether it is north or south?
New time data. Quite a bit different from the pulic story.
Inmarsat Analysis
MH370 measured data against predicted tracks
Times of Doppler measurements
1. 00:30 ACARS Message
2. 00:41 Takeoff
3. 00:43 ACARS Message
4. 00:55 ACARS Message
5. 01:07 ACARS Message
GAP >1 hour gap in ACARS and Handshakes
6. 02:25 ACARS Message or Ping?
7. 02:27 ACARS Message or Ping?
8. 02:29 ACARS Message or Ping?
GAP > 1 hour gap in ACARS and Handshakes
9. 03:40 Handshake Ping
10. 04:40 Handshake Ping
11. 05:40 Handshake Ping
12. 06:40 Handshake Ping
GAP >91 minute gap in
ACARS and Handshakes
13. 08:11 Final complete Handshake Ping
14. 08:19 Final, “Partial” transmission (no Doppler yet)
15. 09:15 Final Ground Station attempt to shake (unsuccessful)
Way too much speculation about the importance of the 08:19 “partial ping”. Even if that does turn out to be the time of an impact (or closing the hanger door), that has no value at all if the speed assumption is way wrong. If 200 kts, it will just reduce the 1000-2000 mile error on position by 50 miles.
Interesting timeline – thanks. I’m no expert, just someone mystified by the facts (or lack thereof). So is it the ground/satellite that initiates these pings or is it the plane? I’m a bit confused b/c the timing went from :40 after the hour for several hours to :11 after the hour for the last “full” ping at 8:11, which is out of timing sequence – do we know why? It seems to me a satellite would request regular, sequentially timed transmissions, which makes me think the 8:11 ping could have been initiated by the plane?
WhereInTheWorld: I have been looking at that and about 15 other questions on this new data.
My understanding is that routine scheduled ACARS messages are initiated by the aircraft side, but the earth segment initiates pings if expected messages stop coming. The timing is not as periodic as publicly discussed. The pings were not at 4:11 — 8:11 as graphed everywhere now. Lots of things to explain.
I just went to this site
https://www.metabunk.org/threads/mh370-how-the-aaib-and-inmarsat-determined-the-southern-trajectory.3348/
Although it isn’t terribly detailed, it appears that the data correlates with the expected data from a sudden southerly turn and followed by the plane holding a relatively constent heading and speed. That does seem pretty compelling.
However, I don’t quite understand what it means that it doesn’t correlate with the “predicted” northerly route? What predicted route? I’d be curious if there is a northerly route with changes in heading/speed that might also correlate to the data. If the plane was still being intentionally navigated to avoid detection, it may very well not have been on a constant heading nor traveling at a constant speed. To be clear, I am happy to say that I find the southerly data pretty convincing. I was afraid that there it was mostly based on confirmation bias by those who didn’t want to believe the plane could avoid being detected by radar.
Anyone know the headings of those two predicted southerly routes? It would be interesting to see what the angle between the tangent of the arc and the planes heading were at each hour.
The constant speed and direction assumption is the critical assumption. If you assume the plane was circling at 200-250 kts after 03:30, you can still find a good fit to the data. That is how critical the ASSUMPTION is in affecting the solution.
So from that AAIB we see:
“If the ground station has not heard from an aircraft for an hour it will transmit a ‘log on / log off’ message, sometimes referred to as a ‘ping’, using the aircraft’s unique identifier.”
This doesn’t make sense with the 91 minute ping gap from 6:40 to 8:11.
The new timing data may not be complete. The times listed are only for those times when they were able to get a Doppler observation (and I assume a slant range, although I have yet see those). It is possible that there were other earth segment attempts to ping the aircraft that failed, thus no Doppler, thus left out of the list.
@airlandseaman What’s your source for this detailed timeline you’ve posted a few times?
Got it, thanks!
If the ‘handshakes’ are ICMP pings, it would be very simple to send manual pings (the last 3) on top of the set programme.
one source for the time line is here:
https://www.facebook.com/permalink.php?story_fbid=740971779281171&id=178566888854999&stream_ref=10
One theory, basically Goodfellow’s with an addition, Namely point 2. I’ll call it Betterfellow.
1. An accidental fire (batteries, tires, etc) sends toxic fumes into the cockpit. They cut some circuit breakers attempting to isolate it, which also cuts off communications. They turn left toward the closest airport Penang, and make a quick descent to insure oxygen.
2. Realizing they might quickly become incapacitated, they plot an autopilot route intended to prevent a crash landing in a populated area. The route stays over water through the Malacca strait, then south into the abyss of the Indian Ocean. As part of the Inmarsat calculations, I might also check if the paths they predict go through a waypoint in Antarctica they might have used (South Pole or otherwise). Can someone here confirm if Autopilot can be programmed to make multiple turns at a later point??? Seems like an option it would have, but some analysts seem to use a turn as evidence of a human at the controls
3. Within a relatively short time, fumes incapacitate the pilots (hence no attempt at communication) and it’s the ghost plane (at least in the cockpit) over water until running out of fuel.
It occurs to me that the IOR Inmarsat S/C, with a significant inclination, could provide the means to solve for a crude absolute path, not just hemisphere ambiguous LOPs and Doppler. If one used a single “Grand Solution” for all the equations of motion, for all 12 observation sets, in a LSF/Kalman filter type solution, you get math not unlike what is used for older LEO navigation satellites like Transit. IOW…A single moving satellite is essentially like having 12 quasi independent satellites from which we can triangulate. Oversimplified, but it helps to visualize what is going on. Of course, the geometric dilution associated with a geo s/c moving a few degrees is much greater than what you get with a 15 minute Transit pass, but potentially informative. Note that this is apparently the information used by Inmarsat to conclude the aircraft went south, not north. But there may be more that can be squeezed out.
Some thoughts.
First we have two candidates for disambiguating the north v. south scenarios:
1 – earth curvature: seems right, given satellite not centered on the equator. Signals from a south-moving plane look different from those of a north-moving plane. Except … I wish I knew exactly how they would look different.
2 – moving satellite. Golden. The satellite itself is moving north and south by small amounts. All you need for a simple doppler-shift solution and you can get what they have without considering earth curvature at all. They calibrated it against other north-south planes in the area to account for atmospherics and possibly scale the exact magnitudes they were seeing.
Method 2 seems sufficient to me. Why do we need curvature?
Second, their two key assumptions: 400-450 knots and straight line flight. In the Malaysian govt release, the difference between 400 and 450 translate to a big difference on the ground. Plane could have been limping along at 200 knots. Especially if incapacitated in some way. That search could be way way off.
Maybe magnitude scaling gives the speed. If there’s only one speed that can produce a given doppler shift wrt a moving satellite. To get an actual speed (and not just a direction) you’d need to know exactly how fast the satellite is traveling south at the time. But with other planes to compare with — you know their speed — then just compare your mystery ship with theirs.
Hal: You are exactly right. People chatting here:
http://www.duncansteel.com/archives/362
…are closing in on it. All we need are a few numbers from Inmarsat and we could generate a Crowd Solution in a day. Nearly everything required is known. Let’s review.
What we have:
1. Exact NOC ground station location
2. Exact satellite location vs. time
3. Aircraft position on the runway immediately before flight (calibrates the total time delay bias).
4. Maps of the GPS integrated water vapor delay (small correction).
5. Physics
6. COTS and University Orbit and link models that are already close to what is needed.
What is needed for each of the 12 (13?) transmissions:
1. Inmarsat best estimates of the free space single path time delays between the satellite antenna and the Aircraft antenna. We do not want estimates ranges, which have additional propagation assumptions embedded.
2. Inmarsat best estimates of the contemporaneous net aircraft Doppler frequency after correcting for all known, calibrated sources of error. (Total Doppler for the satellite – Aircraft is OK.)
2. exact times for #1
It would also be nice if Inmarsat could verify or at least concur in the assessment that:
1. The first 4 samples were generated by standard ACARS messages.
2. The gap between 01:07 and 03:40 contained 3 emergency alerts (initiated by the aircraft radio) around 02:25-02:29 containing engine data (which includes ambient pressure sensor data?).
4. The next 4 transmissions were Pings initiated from the NOC ground station.
5. The final “partial ping” transmission was not innitaited by the NOC and was not, in fact a ping. Instead, it was a 4th emergency alert generated by the aircraft.
That’s about it. We could wrap this in a day if we had the data.
Even if this model only generates a 200-300 mile radius for the final 08:19 solution, if it did not rely on a fixed speed assumption, it might be far more realistic than what we have so far, based on a constant 400-450 kts assumption. And given the delay in finding debris, even if they do find debris at this point, the ocean models are not going to tell you where the aircraft went in to the accuracy that a Transit Navigation satellite style Grand Solution could yield.
When comparing MH370 to the sample flights were they comparing apples to apples? I am not mathematically or technologically savvy and therefore I try to visualize. So we have this satellite in an elliptical movement/wobble sending and receiving signals. Let’s say the satellite was in the 12 o’clock position when MH370 departed KL and at the time of the final pings it was in the 8 o’clock position. So wouldn’t the flights used as comparison have to follow the same timeline starting at 12 o’clock and ending at 8 o’clock? Or suppose some of the reference flights started at 6 o’clock and ended at 2 o’clock, what would that do to the calculations? Again, were they comparing apples to apples or apples to oranges?
@Gene
Guessing here, but I assume that they didn’t compare other flights to the exact route & time as estimated for MH370.
Rather, they compared their modelling system to the known routes of those other aircraft, to validate that the model using satellite data matches an actual route. IOW, apply the same method to data received from a known flight to plot its path, then look at actual path, and see if your method is reliable.
@Gene @David
Exactly – I do not know what flights they compared, but as I said earlier in this discussion, they could have compared Malaysia Air flight 125 (KL to Perth) vs. a normal Malayasia Air flight 370 (KL to Beijing). Beijing is approx 40N 116E and Perth is approx 32S 115E. you could use other flights to other N & S places as well but these flights are nice since they closely mirror N vs S and flight to Perth would be close-ish to where they think the missing 370 ended.
Why all the suspicion? do we really think the UK version of the NTSB and a private company like Inmarsat is going to put their reputations on the line by faking this all? For what? to protect Malaysia or Indonesia from the wrath of China for mistakenly shooting the plane down? Or to hide that the plane is in Kazakhstan? I dont buy it. we had a north and a south arc. Inmarsat proved the plane was on the south arc. THERE IS NO LAND along the south arc – other than indonesia and christmas island. The plane ended in the water – period. The plane flew for 7+ hours – so it had to have climbed back up to altitude (I dont get why the commentators on CNN keep talking about 12000 ft – that was only for the turn around to try to land at the emergency airport or to evade local traffic and radar – you pick). Given the south arc, given the altitude, we just dont know the speed and we dont know if the plane went in a straight line. so technically it could be anywhere on the south arc – but in all likelihood, especially with the more debris being seen – its basically where they said it was. which is still a huge area and it may take yrs to find the actual wreck and black boxes. some folks have suggested that we could maybe even retrieve cell phones and see what was on them – last outgoing text messages or videos. Alas the voice recorder will only have the last 2 hrs worth.
The plane is where they say it is – why this all happened we do not know
@Lee
I question it because it can be questioned. After my previous post I had a look at flights by Malaysia airlines and it currently has both 6pm and 12am departures from KUL to PEK. Now if the wobble occurs at regular intervals of 2,3 and 6 hours then my question is irrelevant. If not, then there is some uncertainty. What that means I don’t know…
https://www.google.ca/flights/#search;f=KUL;t=PEK;d=2014-04-11;r=2014-04-15
@Gene
OK – how about this:
Malay Air flight 125 KUL-PER departs 9:30a
Malay Air flight 376 KUL-CAN departs 9:35a
Now Guangzhou is not quite as good a mirror of Perth – its 23N/113E – so not nearly as north as Beijing (40N) but Perth isnt that far south (32S) so really Guangzhou is just 9 degrees off from a mirror of Perth and Beijing was 8 degrees. And they depart at the same time. From the sounds of it inmarsat has taken ALL of this into account. Its fair to question them and any work that has been done, but they strike me as being thorough and straightforward. I do not think there is any intentional misleading here.
I agree that the circumstances of this plane disappearance are strange / coincidental
– lost contact and transponder exactly when they did the hand off from KL to Vietnam
– several turns reported that MAYBE were to evade Malay and indonesia land mass
– drop in altitude that MAYBE was to evade radar
– ACARS is off
– plane disappears – perhaps to the deepest roughest, hardest to get to place it could
Though I think there could be explainations and coincidences for lots of those. Maybe it was a fire or depressurization and emergency handling and then loss of consciousness, maybe it was a hijack and a fight, maybe a test run of a hijack or a cyber take over, and the plane was hidden in deep ocean to cover up. Maybe the pilot – whose wife in some reports had just left him and he was somewhat distraught, decided to commit suicide but instead of nose down – he essentially went for a joy ride – like some people just get in a car and drive mindlessly if something is on their mind – well he flew and flew until he was out of fuel. Ive suggested all those ideas on this thread way above (as have others – not unique to me of course – though few people seem to buy my suicide joy ride).
But what I dont get is the desire to suggest conspiracy by inmarsat & the UK govt. You seem to be suggesting conspiracy. If you are just suggesting that inmarsat folks made mistakes and didnt take into account the position of their own satellite, time of day of flights, etc, well sure anyone can make mistakes, but sounds to me like inmarsat folks were very thorough and worked hard this past weekend to prove their hypothesis.
Seems to me theres plenty to question here (speed of aircraft, why this happened, who did it, how the search & recovery is being handled from a people and science point of view, what country has radar, all sorts of wrong early reports) but of all the things – inmarsat had not release data before – errors in reporting was the fault of the networks – inmarsat seems to be very precise in what they say and when they say it. Of all the sources, they seem the best – and yes of course in a conspiracy that would make them the perfect place to execute a conspiracy since they are credible. but really?
@Hal
Doppler shift is a function of speed and direction. The shift seen a particular speed moving directly away from the satellite can be equal to the shift seen at a higher speed moving away at an angle.
It’s a matter of vectors, which is why the speed assumption is crucial to the doppler analysis.
Re the Inmarsat correlation discussion:
My understanding is that they used other flights with known positions to verify that they could resolve the north south question by exploiting the satellite’s high inclination (+/- 1.67 degrees). See this site for a graphic of the spacecraft motion during the time of the MH370 flight:
http://www.duncansteel.com/archives/362
There are simple and more sophisticated ways to use the information, but I’m satisfied that exploitation of the fact that the satellite was ALSO moving in a precisely known way can be used to improve the model of where the aircraft went. In fact, the high inclination angle may turn out to yield more than just the general direction. In theory, the fact that the satellite was moving significantly could yield a path without assuming the speed, but the errors will be high compared to a Transit solution. Question is, will they be low enough to put a finer point on the final position at 08:19? It all depends on the measurement errors? I am hoping that the entire Inmarsat system is well sync’ed to GPS clocks, in which case, the precision and accuracy of the time delays and Doppler may be so good that the path is more accurate than anyone is expecting. We just need the Inmarsat data.
If Inmarsat can rule out a path based on the data, then there should be a way to work that equation backwards and, using the observed data, come up with other possible flight paths which would fit the data. (they’re already giving 2 possibilities)
As I understand the data, there are specific times at which the distance between the satellite and the plane is known, and the speed at which the aircraft and satellite were traveling with respect to each other.
A given Latitude (X), Longitude (Y), and Altitude (Z) would result in a distance from the satellite of D.
Given the satellite as the only known reference point, would it not be possible to create the same measured Distance using differrent X,Y, and Z inputs?
Doppler would also be affected by changes in X,Y,Z so that can’t directly be used to check the values.
Assuming that the plane took a linear path after leaving radar coverage is inconsistent with the way it behaved throughout its known course. I think that any path which can match the data should be considered scientifically, without regard to any denials of radar tracks, etc by those territories it might include.
Notwithstanding the repeated sightings of ocean debris over the last few days, there are still multiple solutions to the Doppler ping pattern.
In my lay opinion, it looks to me like the first peak in the graph is a controlled but fast descent at 12:58 or so from 35000 to 12000. The second peak looks like it occurred during a much sharper dive. To me, this looks like a dive from 45000 to 29500 to intercept SQ68.
The remainder of the graph indicates that the satellite was moving south until about 7am. The northern path, assuming 450 knots, would create a much higher Doppler offset than the southern path. But that’s assuming 450 knots.
The real question is, what other speeds at 3:40 could produce the same Doppler effect heading north that the model predicted heading south at 450 knots? Are there any?
I don’t know the answer, but based on the “valley” in the offset, it would appear that this was also the local minima in the relative speed between the satellite and the plane.
This could indeed be because both were heading due south. But it could also mean that the plane was compensating for the satellite’s southern motion by heading west and approaching it. Not due west, because that would drastically lower the offset, but northwest, so that the relative speed was minimal.
Once MH370 reached 8:11, it appears that the satellite was moving north and the plane was moving south. This would be problematic for a ghost flight north, but not for an approach, for example, heading SW.
To clarify, I am not suggesting the plane planned its trip around pings. I am suggesting that by coincidence, a northern solution to the pings seems to work with a heading of 310 degrees or so. Not quite the mirror of the southern path but very close to the typical navigation routes.
@airlandseaman
While well synced clocks would be nice, I’m not sure they are actually necessary, as long as the clocks can maintain accuracy for 8 hours. All of the calculations are made using timings and frequencies as between the satellite and the aircraft. They have ping data from the ground before the aircraft took off, at which time they know the exact location, and the speed is 0. Using those pings, they can determine any offset between the satellite and aircraft clocks and the respective radio frequencies. With that offset as a baseline, as long as the clocks or frequencies don’t drift too much during the flight, syncing shouldn’t matter. (I’d actually be more concerned about frequency drift than clock drift, given the thermal changes through the flight, but I don’t have any hard data about the radios used or their compensation methods)
@JS asks: The real question is, what other speeds at 3:40 could produce the same Doppler effect heading north that the model predicted heading south at 450 knots? Are there any?
My first answer was “no” because a southerly moving satellite will stretch all northerly plane signals and compress all southerly plane signals. But on further thought … the chart the Malaysians released shows a cross-over point at 22:45:00 so at different speeds you might find cross-over points at different places. Intuition tells me the trends over time would still be distinguishable but I don’t have the math to prove it off the top of my head.