like it or not the prospect of being able to use mobile phones on airplanes is inching ever closer. last week Ryanair, a European low-cost carrier, announced that it would equip its entire fleet of boeing 737s with small base stations, called picocells, provided by OnAir,a technology company backed by Airbus, Europe's aviation giant. the picocells will use satellite links to allow mobile phones to be used during flght without interfering with ground-based networks. (Such interference, rather than safety concerns, is the primary reason that in-flight use of moblie phones is banned at the moment.) Taking a cut of the resulting revenues will help Ryanair to keep its ticket prices down, according to Michael O'Leary, the firm's boss.