5 ms·

To be clear, Flightradar24 and other ADS-B-based online services do not provide enough data to come to a meaningful conclusion about these kinds of accident. Th

To be clear, Flightradar24 and other ADS-B-based online services do not provide enough data to come to a meaningful conclusion about these kinds of accident. The resolution is often too coarse to even see how quickly a plane would've pitched down, assuming it did so quickly.

Scoundreller 8y ago
So they not provide? Not collected? Or is this kind of data not even broadcast in the first place?
- blackflame7000 8y ago
  This data is actually gathered by hobbyist and you can be a part of their network all it costs is about $25 for an ADS-B USB adapter. https://www.flightradar24.com/build-your-own https://www.flightradar24.com/build-your-own They also offer free membership (499/yr) if you share data. Every flight broadcasts this data kinda like GPS and all you need is an antenna to receive it. In fact the tracking is basically done via ground-based GPS(ADS-B) by measuring the time delays between different receivers in the vicinity. The problem is that there aren't many hobbyists in those parts of Africa so coverage is sparse. In America, its pretty spot on in most locations. A USB adapter can surprisingly pick up planes as far away as 400 miles.
  - semi-extrinsic 8y ago
    If someone wants to do this, for the more technical audience there is a selection of better (but still pretty cheap) hardware available e.g. from https://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/ https://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/ E.g. you can get an SDR with built-in ADS-B specific low-noise amplifier and SAW filter also for $25. (This can't do general purpose stuff though, unlike the one linked by parent.) Or you can get their general-purpose SDR and their broadband LNA for $40 total.
  - Scoundreller 8y ago
    So I guess the newly released satellite data was because nobody was running (enough of) these dongles where these incidents occurred?
  - garaetjjte 8y ago
    >by measuring the time delays between different receivers in the vicinity No, position (likely received from plane GPS) is just openly transmitted in ADS-B frame.
shittyadmin 8y ago
Well, the FAA here just drew this conclusion based on ADS-B data picked up from a satellite, so I'm not sure how you're getting that idea. At least, in areas where such sites have good coverage they may actually get closer to the ground data than the satellites are capable of picking up. I don't mean to dump on doing a quality analysis, just that the quality of data is not as drastically different as you're suggesting.
- js2 8y ago
  Not just the ADS-B data, but also from physical evidence collected from the wreckage.
skeletonjelly 8y ago
https://twitter.com/flightaware/status/1105918162451738624 https://twitter.com/flightaware/status/1105918162451738624
lysp 8y ago
Online services actually do have the data available, just their online graphing is a smoothed out version of the data. Generally data is received every 5 seconds. In cases such as Lion Air, they downloaded all the granular data from nearby receivers and provided some analysis in their blog. They also made available the raw data for the public to download: https://www.flightradar24.com/blog/flightradar24-data-regarding-lion-air-flight-jt610/ https://www.flightradar24.com/blog/flightradar24-data-regard...

Scoundreller 8y ago

So they not provide? Not collected? Or is this kind of data not even broadcast in the first place?

blackflame7000 8y ago
This data is actually gathered by hobbyist and you can be a part of their network all it costs is about $25 for an ADS-B USB adapter. https://www.flightradar24.com/build-your-own https://www.flightradar24.com/build-your-own They also offer free membership (499/yr) if you share data. Every flight broadcasts this data kinda like GPS and all you need is an antenna to receive it. In fact the tracking is basically done via ground-based GPS(ADS-B) by measuring the time delays between different receivers in the vicinity. The problem is that there aren't many hobbyists in those parts of Africa so coverage is sparse. In America, its pretty spot on in most locations. A USB adapter can surprisingly pick up planes as far away as 400 miles.
- semi-extrinsic 8y ago
  If someone wants to do this, for the more technical audience there is a selection of better (but still pretty cheap) hardware available e.g. from https://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/ https://www.rtl-sdr.com/buy-rtl-sdr-dvb-t-dongles/ E.g. you can get an SDR with built-in ADS-B specific low-noise amplifier and SAW filter also for $25. (This can't do general purpose stuff though, unlike the one linked by parent.) Or you can get their general-purpose SDR and their broadband LNA for $40 total.
- Scoundreller 8y ago
  So I guess the newly released satellite data was because nobody was running (enough of) these dongles where these incidents occurred?
- garaetjjte 8y ago
  >by measuring the time delays between different receivers in the vicinity No, position (likely received from plane GPS) is just openly transmitted in ADS-B frame.

shittyadmin 8y ago

Well, the FAA here just drew this conclusion based on ADS-B data picked up from a satellite, so I'm not sure how you're getting that idea. At least, in areas where such sites have good coverage they may actually get closer to the ground data than the satellites are capable of picking up. I don't mean to dump on doing a quality analysis, just that the quality of data is not as drastically different as you're suggesting.

js2 8y ago
Not just the ADS-B data, but also from physical evidence collected from the wreckage.

skeletonjelly 8y ago

https://twitter.com/flightaware/status/1105918162451738624 https://twitter.com/flightaware/status/1105918162451738624

lysp 8y ago

Online services actually do have the data available, just their online graphing is a smoothed out version of the data. Generally data is received every 5 seconds. In cases such as Lion Air, they downloaded all the granular data from nearby receivers and provided some analysis in their blog. They also made available the raw data for the public to download: https://www.flightradar24.com/blog/flightradar24-data-regarding-lion-air-flight-jt610/ https://www.flightradar24.com/blog/flightradar24-data-regard...