I was just looking at the adsbexchange website, and was wondering if it was possible for smaller, private aircraft to turn off their ADS-B? I was wondering this because id figure that maybe not everyone wants to have their live flight info publicly available online, especially if its a smaller flight.

I know its illegal to do but in theory is it possible on smaller aircraft in general? And if so, would the only way to track them if they turned off their ADS-B and their Transponder be to use radar?

I'm not a pilot so I may not be too well versed on this subject so thank you.

  • 1
    $\begingroup$ What country, and what airspace? Press Edit to add this info please. $\endgroup$
    – ymb1
    Oct 19 '21 at 19:32
  • $\begingroup$ Welcome to aviation.SE! You said you know it isn't allowed, so I assume you aren't asking about regulations. Are you asking about physically turning it off? If so, this question might have some useful information. $\endgroup$
    – Pondlife
    Oct 19 '21 at 19:34
  • $\begingroup$ In the US it's only illegal in certain types of airspace. In most of the US you don't even need to have a transponder, or in fact even an electrical system in a plane. $\endgroup$
    – TomMcW
    Oct 19 '21 at 19:56
  • $\begingroup$ @Pondlife Hi, Yes I am talking about physically turning it off. $\endgroup$ Oct 19 '21 at 20:38
  • $\begingroup$ @TomMcW In the US, if you have a transponder or ADSB installed, you are required to operate them at all times, even in airspace where you’re not required to have it in the first place. $\endgroup$
    – StephenS
    Oct 20 '21 at 0:16

Yes, it is very possible. As you say, it may be against the rules, but it is possible. ADS-B Out may be integrated in a "standard" 4096-code Mode A/C transponder (which can be disabled), or it may be wired in to another system on the aircraft, such as the anti-collision strobe (which can also be disabled). A standalone ADS-B device may even be plugged into a 12V accessory outlet, though I believe that's more common for an ADS-B In setup (where various data, most importantly nearby traffic, is fed in to a display device)—I'm not sure if that counts as a valid Out setup.

In any case, as the answers at the linked question describe, every electrical device on an aircraft should have the capability to be powered off. In an emergency, especially a fire onboard, the immediate safety of the aircraft and its occupants is prioritized above the generally enhanced safety situation afforded by ADS-B.

But there are other reasons you may not see an aircraft on a flight-tracking website:

  • Pilots can make a request, both with the FAA and with the website, to have their aircraft hidden. This is very common. However, this will not be the reason you do not see an aircraft on ADS-B Exchange; they are very clear that they do not filter or block any aircraft from their data.
  • The website may not have any data feeds nearby. Official ATC displays use ADS-B receiver antennas that are installed and maintained by the government or other appropriate organization; third-party sites may have an arrangement to access some of this data, but if not they must rely on a network of volunteers with privately-owned receivers. There may not be any such volunteers within range of the aircraft.
    • In particular, in the United States, many ADS-B transponders broadcast on a frequency of 1090 MHz, the same as in the rest of the world. But smaller aircraft that will not operate above 18,000' MSL nor outside of the United States may use a cheaper "Universal Access Transceiver" which broadcasts on 978 MHz. Fewer aircraft use this technology which means fewer volunteer receivers are set up for it; if your aircraft of interest has an ADS-B Out device that uses 978 instead of 1090, it is less likely to appear on third-party sites.
  • The aircraft may not have ADS-B Out installed at all, and that may be quite legal. In the United States, 14 CFR 91.225 lists the airspace where ADS-B Out is required, and it is not "all airspace" by any means (though it does include the airspace in and above busier airports, as well as all airspace above 10,000' MSL that is at least 2,500' above the ground).

And yes, if the the aircraft's ADS-B is turned off the only way to track them would be by using their transponder (secondary radar) or listening for an echo bouncing off the physical aircraft (primary radar). And if the pilot turned off the transponder as well, primary radar would be the only automated means of tracking the aircraft. This would still be quite possible, as long as the aircraft was high enough; one of the benefits of ADS-B is that the cheaper receiver sites allow for greatly increased low-altitude coverage, which the expensive primary radar antennas do not always provide (see: Can someone actually "fly under the radar"?).

Note that even in non-radar airspace known aircraft can be "tracked" if the pilot reports over a known location at a known time, and ideally provides an estimate of when they will be over the next location.

  • $\begingroup$ There are no ADSB-Out devices that plug in to your accessory outlet. They all have to be permanently mounted and comply with FAA regs. faa.gov/documentLibrary/media/Advisory_Circular/AC_20-165B.pdf $\endgroup$
    – JScarry
    Oct 19 '21 at 22:33
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    $\begingroup$ @JScarry There actually are ADS-B Out devices that plug in to your accessory outlet. The FAA isn't the only aviation regulation body in the world, and there are countries where portable units do meet local regulations. $\endgroup$ Oct 20 '21 at 4:55
  • $\begingroup$ @HiddenWindshield A popular example being the "SkyEcho" which is a portable device for use in the UK $\endgroup$
    – Dan
    Oct 20 '21 at 7:36
  • $\begingroup$ @HiddenWindshield Good to know. $\endgroup$
    – JScarry
    Oct 20 '21 at 16:06

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