After 35 years of travel writing, I was on one of the strangest adventures of my life. I was crossing the southwestern US in a small but powerful two-seater aeroplane called an AirCam. It looks like a double kayak with cloth-covered wings, two humongous engines and flimsy-looking landing wheels. It has no cockpit. The plane is controlled, up to its maximum altitude of 17,500ft, by a joystick.