I assume that local control, (i.e. tower controller/ground controller) would want to distinguish between an airport ops vehicle, fire apparatus, sweeper, plow, EMT, law enforcement etc v.s. an aircraft.
I could be mistaken.
Regardless, because I live within 1/4 mile of KFLL, my monthly statistics are skewed unfairly v.s. other participants whose setup is not in close proximity of an airport where they would, otherwise, pick up airport ground traffic.
It is common for that distinction to be made in a way that is specific to the airport - perhaps using a reserved address range, or particular callsigns. Vehicles don’t move from airport to airport so often so it doesn’t have to be a globally-agreed system. Setting the ADS-B category field doesn’t seem so common.
You could look at your aircraft.json for the “category” field to see how effective it would be in your area for distinguishing vehicles from aircraft.
Here in PHL, all ground vehicles have an ICAO code that converts to N7xxXB. Most of them even ident their actual vehicle number. Airports ops are A9, A10, A209, A219, A229 and others. There’s also MEDIC30 and F8 and F10 of ARFF. I forget what all the snow removal trucks use, but they all have ADS-B and show up on the map.
Actually, they’re not forgetting…they’re following the rules:
14 CFR 91.225 (f) Each person operating an aircraft equipped with ADS-B Out must operate this equipment in the transmit mode at all times.
There really isn’t a “standby” mode for ADS-B. You’re thinking of a mode C transponder or standard mode S (w/o ADS-B), however even those should be “ON” at all times, as explained in the AIM:
AIM 4-1-20 a. 3. Civil and military transponders should be adjusted to the “on" or normal operating position as soon as practical and remain on during all operations unless requested to change to “standby" from ATC
7. If operating at an airport with Airport Surface Detection Equipment - Model X (ASDE-X), transponders should be transmitting (on position) continuously with altitude reporting while moving on the airport surface.
8. Aircraft equipped with ADS-B (1090 ES or UAT) must operate the equipment in the transmit mode (on position) at all times while on any airport surface.
We are planning to use a ground vehicle icon in a future dump1090 map release. However, as already noted on this thread, this is dependent on the vehicle identifying itself as a ground vehicle “category” properly per the Mode S specifications.
There are no plans at the moment to filter ground vehicles from the statistics page.