3 ms·

I feel like I've seen lots of geophysical survey aircraft using ADS-B for their entire flights. Do you have a reference?

defrost 2y ago
Sure, we kept it off during aquisition on all 14 airframes for hundreds of millions of line kilometres gathered across multiple countries; Mali, Fiji, PNG, Central and Northern Australia, the DRCs, various 'stans, India | Pakistan and elsewhere. Perhaps others had different practices or flew different instruments such as optical photogrammetry. If you're seeing gridding at 80m ground clearence perhaps it's crop spraying or perhaps your software is infilling lines from turnpoint position blipping with nothing for the next 50km. EDIT: I note you submitted this article and have an interest in aerial surveillance programs, I'm simply recounting the practices of one rather busy Australian geophysics company thta was subsumed into Fugro some time past. We considered aircraft and crew safety and had a 20+ year no crash no lives lost record and regularly considered aircraft position signals .. that said we avoided "polluting" the spectrum with broadcasts when aquiring signal and largely relied on off grid checkins (even just three radio blips) ever few completed lines. I dare say some operators contracted for non EM work (say, radiometric survey) might broadcast during aquisition lines but I find it hard to believe that a good operator would broadcast during EM runs.
- jjwiseman 2y ago
  I was thinking of airborne electromagnetic (AEM) surveys (e.g., https://www.ramboll.com/projects/water/aem-mapping-california-s-groundwater https://www.ramboll.com/projects/water/aem-mapping-californi...) when I wrote that, but after checking my notes, I found that I had misremembered: I actually hadn't been able to find any ADS-B tracks that were clearly survey flights!
  - defrost 2y ago
    That tracks .. geophys surveys, whether active (sending out signal to ground and listening to the return) or passive (bat airs across the spectrums), are predicated on having as 'neutral' a recording post as possible .. blatting out radio spectrum data that would have to be removed from the record in post just isn't "the way". Aeromag and radiometrics tend to be low level and tight; 80m ground clearance, 200m line spacing (unless for regional levelling of multiple small infill surveys). Photogrammatic sureys are higher with much wider spacing, the frames are large and there's really only need for a 50m or less overlap to get a good broad area mosaic. I'm guessing you have routines to analyse and classify flight activity by path characteristics and coarsely bucket activity?

defrost 2y ago

Sure, we kept it off during aquisition on all 14 airframes for hundreds of millions of line kilometres gathered across multiple countries; Mali, Fiji, PNG, Central and Northern Australia, the DRCs, various 'stans, India | Pakistan and elsewhere. Perhaps others had different practices or flew different instruments such as optical photogrammetry. If you're seeing gridding at 80m ground clearence perhaps it's crop spraying or perhaps your software is infilling lines from turnpoint position blipping with nothing for the next 50km. EDIT: I note you submitted this article and have an interest in aerial surveillance programs, I'm simply recounting the practices of one rather busy Australian geophysics company thta was subsumed into Fugro some time past. We considered aircraft and crew safety and had a 20+ year no crash no lives lost record and regularly considered aircraft position signals .. that said we avoided "polluting" the spectrum with broadcasts when aquiring signal and largely relied on off grid checkins (even just three radio blips) ever few completed lines. I dare say some operators contracted for non EM work (say, radiometric survey) might broadcast during aquisition lines but I find it hard to believe that a good operator would broadcast during EM runs.

jjwiseman 2y ago
I was thinking of airborne electromagnetic (AEM) surveys (e.g., https://www.ramboll.com/projects/water/aem-mapping-california-s-groundwater https://www.ramboll.com/projects/water/aem-mapping-californi...) when I wrote that, but after checking my notes, I found that I had misremembered: I actually hadn't been able to find any ADS-B tracks that were clearly survey flights!
- defrost 2y ago
  That tracks .. geophys surveys, whether active (sending out signal to ground and listening to the return) or passive (bat airs across the spectrums), are predicated on having as 'neutral' a recording post as possible .. blatting out radio spectrum data that would have to be removed from the record in post just isn't "the way". Aeromag and radiometrics tend to be low level and tight; 80m ground clearance, 200m line spacing (unless for regional levelling of multiple small infill surveys). Photogrammatic sureys are higher with much wider spacing, the frames are large and there's really only need for a 50m or less overlap to get a good broad area mosaic. I'm guessing you have routines to analyse and classify flight activity by path characteristics and coarsely bucket activity?