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by jhugo 1613 days ago
Since 2020-01-01, ADS-B is a requirement in a lot of US airspace (FAR 91.225). Turning it off is allowed for govt / intelligence / law enforcement / military only. Many countries have similar requirements.

People often think an aircraft is flying with transponder off because it doesn't appear on FR24/FlightAware. In fact these companies allow blocking aircraft from their service; this is why ADS-B Exchange is better.
3 comments
motohagiography 1613 days ago
Not a pilot, but played with ADS-B tracking several years ago, and my impression was below something like 4-5000' the transponder wasn't required to transmit location. This meant that surveillance aircraft (usually single engine propeller craft and helicopters) didn't send GPS, only the fact that it was in the air.
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jhugo 1612 days ago
Yeah. It's a requirement in a lot of US airspace, but not all airspace. Even at low altitudes it's required near major airports though.

Surveillance aircraft, if operated by a government entity, would not be required to transmit anyway. (Though they may choose to for safety purposes if it doesn't compromise the mission, just as the military often do in busy airspace.)

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Naracion 1613 days ago
If turning ADSB off is only allowed for government / military / intelligence airplanes, would using a CV algorithm to capture these airplanes be against the law?

Recently there was a post of Google satellite cameras capturing a B-2 Stealth Bomber showing up on Google Maps [1]. Would such planes be captured by a vision system only, and would that be of concern to the government that might be trying to keep it undetected?

1: https://www.google.com/maps/place/39%C2%B001%2718.5%22N+93%C...

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brokenmachine 1613 days ago
I don't see a B2 at your link?
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Naracion 1611 days ago
Oh wow, they removed it. I apologize, I simply shared the link that had been shared before in December 2021. I should also have taken a screenshot.

Here is the HN post: https://news.ycombinator.com/item?id=29627105

Here's a Techradar post on this: https://www.techradar.com/news/eagle-eyed-redditor-spots-a-f...

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aqfamnzc 1613 days ago
In fact, ADS-B E has an option to filter only aircraft not shown on other sites :)
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