Forget the ornithopter, and don’t even bother going down Icarus’ failed flight plan. The real way to fly, and really fly, is to strap on a paraglider and shoot straight for the skies. Granted, it’s not for the faint-hearted, but sitting in a plane or even a helicopter doesn’t quite cut the mustard.
Yes, no engines, and certainly no pollution, too. Paragliding is a non-motorised form of flight that uses a parachute and air flow for its motion, so all that’s involved are man (or woman), fabric, the elements and sheer grit.