Wikipedia
Warflying or warstorming is an activity consisting of using an airplane and a Wi-Fi-equipped computer, such as a laptop or a PDA, to detect Wi-Fi wireless networks. Warstorming shares similarities to Wardriving and Warwalking in all aspects except for the method of transport.
It originated in Western Australia with the WaFreeNet (WAFN) group taking up a Grumman Tiger four-seater near Perth City in 2002, as documented on the weblog of Jason Jordan
Most warflying is harmless, as most of the people will just scan for the networks, either as an experiment, or just for the pure amusement, or to map out the wireless networks in the area. Due to the nature of flying, it is much more difficult to attempt to access open networks while warflying.