sentences:  Although long-coveted, Business Express was unable to operate the BAe 146 on the lucrative Boston Logan-Washington National sector due to landing slot restrictions on four-engine aircraft, and a primary reason these units did not succeed as significant revenue generators for the airline.In an effort to establish a larger regional identity, Business Express launched the 'Fly BEX Jets' program in 1994 on the Boston-Baltimore-Washington sector.The aggressive marketing scheme offered free round-trip flight vouchers for every round-trip flown on BAe-146 aircraft.