Transponders also use a lot of power.. assuming you are looking for 'real' aircraft to see them. Most of the hobby class drones don't have the payload capacity

Transponders also use a lot of power.. assuming you are looking for 'real' aircraft to see them. Most of the hobby class drones don't have the payload capacity for extra battery. Even a Cessna can't pull of a transponder if the alternator goes bad (for very long). The N number is there for when the drone crashes into something/someone. They had dropped the requirement for a while - looks like it is back on again.