5 ms·
I don't know if others here also read the really interesting technical report on how the searchers used very presciently recorded data from Inmarsat to figure o
by supernova87a 5y ago
I don't know if others here also read the really interesting technical report on how the searchers used very presciently recorded data from Inmarsat to figure out where MH370 may have gone. (not the government overall incident summary or similar, but the paper in the Journal of Navigation, which I didn't know was a thing)
It turned out that after the previous (Air France?) loss of aircraft, Inmarsat's operations team/executive decided that they should preserve data about the Burst Timing Offset (BTO) and Burst Frequency Offset (BFO) of every transmission to/from aircraft instead of discarding it as unneeded data (their disks were filling up). That data records the returned ping frequency and timing offset (hence the names) of the plane's transmissions to/from the satellites, even if it's just for a handshake, and no meaningful voice/data content is exchanged.
After all, if a perfunctory handshake message contains no content, why save something as esoteric as the Doppler-shifted frequency you received it back on, or the timing difference?
The executive in charge of that said, impressively, "we didn't exactly know why we might need it in the future, but we thought we should save that data." (paraphrasing, can't quite find the original quote right now)
That frequency + timing offset was the key information in figuring out what radial + distance the plane may have been flying on, for 7 hours after all other systems stopped reporting, based on the hourly handshakes/pings of the sat-phone system. All other data reporting systems had gone offline or out of distance. They tested it against other aircraft (in same geographic area, time, and of same type even!) whose positions were known, and had confidence it was trustworthy enough to base the search areas on.
It was a fascinating read to me at least.
https://www.cambridge.org/core/journals/journal-of-navigation/article/search-for-mh370/D2D1C4C99E7BFDE35841CFD70081114A https://www.cambridge.org/core/journals/journal-of-navigatio...
and more generally:
https://en.wikipedia.org/wiki/Malaysia_Airlines_Flight_370_satellite_communications https://en.wikipedia.org/wiki/Malaysia_Airlines_Flight_370_s...
- andi999 5y agoWhat surprises me about path reconstructed from immersat: the angle to the satellite is always the same, but the pilot didn't know (or care) the position of the satellite. So there is no reason to follow such a path (a straight path would change the angle) . This seems like a too big coincidence. To me the only explanation (except a huge coincidence) is either a stationary plane or of course faulty data.
- Someone 5y ago> The executive in charge of that said, impressively, "we didn't exactly know why we might need it in the future, but we thought we should save that data." Nowadays, that could be a GDPR violation.
- tpxl 5y agoI very much doubt plane ping time is covered under GDPR.
- TheManInThePub 5y agoI'm disappointed to find somebody so woefully misinformed about GDPR on HN. GDPR only relates to personal data. The data discussed here clearly isn't personal by any stretch of the imagination. This is the same mentality that thinks ordinary website cookies fall under the GDPR. They don't, unless you are using them to track me or identify me (advertisers take a bow), in which case, you need to ask my permission to do so. And so you should.
- iSnow 5y agoNo, GDPR deals with personal, identifiable data.
- Someone 5y agoI know complaining about downvotes is futile, but I said “could”. Also, if you google “are car number plates personal data”, I don’t think anybody can reasonably conclude that is incorrect for car number plates. Certainly, https://sapphireconsulting.co.uk/2020/07/17/is-a-car-registration-plate-my-personal-data/ https://sapphireconsulting.co.uk/2020/07/17/is-a-car-registr..., http://www.privacylegal.eu/personaldata.html http://www.privacylegal.eu/personaldata.html, https://ec.europa.eu/eurostat/documents/205002/10379059/DPR-EC-02566_privacy_statement_LUCAS.pdf https://ec.europa.eu/eurostat/documents/205002/10379059/DPR-..., https://ico.org.uk/for-organisations/guide-to-data-protection/guide-to-the-general-data-protection-regulation-gdpr/what-is-personal-data/can-we-identify-an-individual-indirectly/ https://ico.org.uk/for-organisations/guide-to-data-protectio..., https://www.whatdotheyknow.com/request/car_number_plates_personal_infor https://www.whatdotheyknow.com/request/car_number_plates_per... (to pick a few from google’s first result page) agree car number plates could be personal data. I don’t see why plane number plates would be different. Yes, few planes are privately owned, but some definitely are, and they store data that can be used to find out where your plane was. Also, if there is personal data in there, “we didn’t know whether it would ever be used, but started recording this information anyways” clearly is against the GDPR. So, I stand by my claim this could be a GDPR violation nowadays.