The flight data recorder aboard commercial airliners often yields important clues about the last moments before a crash. But the traditional shielded, twisted wiring used to collect parameters from remote sensors lacks sufficient sensitivity. Raytheon's Commercial Electronics Div. has come up with an alternative, designing a fiber optic data bus consisting of seven identical collection units placed near sensors. Each unit will be connected to a fiber optic ring that enables data to be transmitted in either direction to the flight data recorder.