Drones aren't yet licensed to carry passengers, but some may already be airlifting wounded personnel off the battlefield and could be employed for smuggling people Still from a promotional video for Skysurfer, a US company that sells "ultralight aircraft" for personal, recreational use The first passenger-carrying drones may already be in use. These aren't sophisticated urban air taxis, but crudely modified cargo drones transporting combat casualties and criminals. Heavy-lift drones are essentially scaled-up versions of the familiar quadcopters. Hair-raising videos of hobbyists carried by home-made drones show that the basic technology is simple enough. But meeting aircraft safety requirements for passenger transport takes years, and drone-makers, including Volocopter, EHang and Eve Air Mobility, are all aiming to get vehicles certified this year or next.

Learning reliably safe autonomous control is one of the core problems in trustworthy autonomy.