Editor's note: Several reporters are pointing to tweets saying that they are the source of the bomb threat scare at Hartsfield-Jackson Airport. It should be noted that officials have yet to specify the nature or origin of these threats, other than deeming them "credible." - Aaron
Air travel is a form of travel in vehicles such as airplanes, helicopters, hot air balloons, blimps, gliders, hang gliding, parachuting, or anything else that can sustain flight. Use of air travel has greatly increased in recent decades - worldwide it doubled between the mid-1980s and the year 2000.