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How Satellite Company Inmarsat Tracked Down MH370
mdsolar (1045926) writes "Malaysian Prime Minister Najib Razak has announced that, based on satellite data analysis from UK company Inmarsat, Malayian Airlines flight MH370 ended in the southern Indian Ocean, and no one on board survived. 'Effectually we looked at the doppler effect, which is the change in frequency, due to the movement of a satellite in its orbit. What that then gave us was a predicted path for the northerly route and a predicted path the southerly route,' explained Chris McLaughlin, senior vice president of external affairs at Inmarsat. 'What we discovered was a correlation with the southerly route and not with the northern route after the final turn that the aircraft made, so we could be as close to certain as anybody could be in that situation that it went south. Where we then went was to work out where the last ping was, knowing that the aircraft still had some fuel, but that it would have run out before the next automated ping. We don't know what speed the aircraft was flying at, but we assumed about 450 knots.' Inmarsat passed the relevant analysis to the UK Air Accidents Investigation Branch (AAIB) yesterday. The cause of the crash remains a mystery."
We still have no idea exactly where the aircraft is, how it went down, or what to do now.
How come the frequency information of the signal received by the satellite was saved? What is the purpose of saving all that data in normal operations?
The communications system in question is likely based on TDMA (Time Division Multiple Access). While I have not worked with Inmarsat systems, all the other satcom systems I have worked with log each connection, and various pieces of information regarding the connection. One of these parameters that is logged is the frequency offset (ie the difference between the expected and actual frequency). This is useful from a troubleshooting perspective as it allows you to spot transmitter and receiver components that are drifting out of specification. Some of the more advanced satellite systems (iDirect) will actually log the geographic coordinates of the uplink site, as this plays into the timing requirements for the network. Unfortunately, Inmarsat isn't this aggressive with their timing, so time of flight isn't an issue).
And why did it take three weeks to do that analysis?
This is pure speculation on my part, but I would wager they had to go back through significant amounts of logs in order to characterize the transmitter and receiver components on that particular aircraft. The doppler effect is going to be subtle compared to the thermal drift of the transmitter, so they need to factor that out before they can get at the thermal drift. Also every oscillator and transmitter is different, so they would need to characterize the transmitter that is on that specific aircraft (which is now of course missing).
...si hoc legere nimium eruditionis habes...
CVRs on those aircraft are 2 hours, not 30 minutes.
What I want to know, is why my phone (the smallest model made) can hold 1100 hours of compressed audio ... but these aircraft using NAND don't hold more than 2 hours of uncompressed audio (you don't want any quality sacrifices or artifacts from compression to screw up your analysis later) in a redundant array ...
Someones going to tell me that for the 30-40k those black boxes cost ... they can't put some actual storage space in the fucking things?
Persistent Volume manager for Kubernetes - https://github.com/dwimsey/openshift-pvmanager
As a supervillian I prefer locations such as this, such as my base deep on the ocean floor. Hopefully they don't find it when they look for the damn plane.
I don't know why anyone would find that disturbing.
In Tres Roeder's "A Sixth Sense for Project Management," he shows a diagram of communications. This diagram shows information versus time.
In the beginning, information is unknown; then the information changes, back and forth. For example: a dollar estimate may be $3,000 for a project, then $85,000 when we realize we need to excavate cabling tunnels for a line, then $6,000 when we realize we can run this across our existing tunnel and have a new fiber optic pulled for $3,000, then $7,000 when we realize we're going to also need a new transceiver, then $4000 when we find out some of the other equipment is unnecessary, then $14,000 when we realize the scope of labor required is twice as big.
Finally, once we have enough information, that figure stays. Perhaps at $14,000. We also realize we've got the correct figure because we have a full analysis of scope and work required--or at least, the figure won't change until we've done a bunch of work and realized, deep into the project, that we missed something. In any case, it is now not likely to change simply because our information base is hot.
During the initial planning phase, communication should reflect this: the understanding of the situation--the lack of precision--and what is being done to pin that down is to be communicated; conclusive statements should not be communicated because the current understanding of the situation is inconclusive. Once the situation has reached a point of conclusion, then you communicate these conclusions.
What is disturbing about the Malaysian government here is they have been repeatedly saying, "We have no idea what's happening and there's a ton of information out there we're missing; but this is what happened." Then, five hours later, "Oh we found more debris, we think this happened instead." Then the next day, "Oh there was some satellite telemetry information we weren't done analyzing, but it's provided additional information, so we think the plane may have gone this way..."
In other words: They have piles of information they know they're missing, piles of information they have a plan for finding (i.e. "ongoing investigation"), and huge and visible gaps they know exist and expect to fill. They should not be communicating any conclusions at this time.
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While this has captured much attention, quite honestly it is a yawner. Did you know that approximately 150,000 other people died that day? I'm willing to bet more than 2500 were preventable in some manner, making that 10x more important than MH370.
When you step back and actually review numbers, many things seem insignificant, if you have no personal feelings or emotions tying you to the event. Like this post, discussion, and website.
I finally updated my sig, but now it's lame.