The EU reportedly is testing an aviation security system that would put a network of cameras, microphones and sensors on commercial airliners. All the data would be aggregated by a computer, which would signal an alert in the cockpit if a threatening behavior pattern was detected. "What we are doing is extending technology which is already used at airports and railway stations and placing it on an aircraft," says James Ferryman, who is heading the government-sponsored research at Reading University in England. But some civil libertarians have expressed alarm, especially when it comes to eavesdropping. "The day the airlines install hidden microphones on planes is the day that all trust in the airlines is destroyed," says Simon Davies of Privacy International.