"My life hangs by the threads of Keviar parachute lines. My hands fumble while changing lenses on the camera dangling from my neck. I’m afraid of dropping a lens and having it fall into the propeller whirling at my back. At 7,500 feet, I’m higher than I’d planned to go, but it’s the only way to gain the perspective I want on the immense volcanic crater below. Concentrating on my viewfinder helps control the fear.

I’m soaring above the central Sahara in a powered paraglider, a single-seat aircraft that looks like a flying lawn chair. Developed in France, it combines an inflated, parachute-like wing with a 50-pound motorised backpack. With three gallons of gas I can stay up for about two hours. But a sudden gust can cause its air-filled wing to collapse catastrophically. And there is always the danger of being blown so far off course that I would die of thirst or exposure before my companions found me. Deciding to use the motorised paraglider was difficult, but I had little choice. In country that counts few airplanes and no helicopters, I needed a portable craft that I could haul around the roadless desert."