The only way to the strips is ___1_____by greatly simplifying controllers’ jobs, for nobody has found a way to h___2____ and share such complex information on computer screens. And s_____3_____ the controllers’ jobs has indeed begun to happen in places, by having planes stick to strictly d____4_____ flight paths in unvarying p___5______ order on courses that never cross. Even then, when computers have taken over, the controllers have continued to keep paper flight strips f__6____ backup and for a record in case of litigation.