Have you seen the size of a transponder? You're not going to put that in a drone doing 1h flights. They're about 1/2kg. 4G is more likely, but coverage can be a

Have you seen the size of a transponder? You're not going to put that in a drone doing 1h flights. They're about 1/2kg. 4G is more likely, but coverage can be an issue. The bigger drones that could carry one are much bigger, and they fly for several hours, but they do not have the same ease of use as the smaller ones. Flarm and Adsb (mostly in for now, out is more difficult/heavy but there are a few prototypes) are seeing some use. Companies are also trying to standardise around existing aeronautical standards, or to create new ones where needed. But it's a free market and it's not clear which solution will win in the end. The regulators are also closely following.