Over the 1960s, the airline saw significant growth, concerning both its route network and fleet of Soviet-built aircraft. The Ilyushin Il-18 turboprop airliner became the backbone of Interflug's short haul flights during that period. The company had been the intended primary operator of the Baade 152, an early jet airliner constructed in East Germany. The development never went beyond the prototype phase, though, and was abandoned in 1961. In 1969, the Tupolev Tu-134 was introduced, the first jet airliner operated by Interflug. It was operated on the airline's European routes. The long range Il-62 became part of the fleet in 1971. In the same year, the number of annual Interflug passengers reached 1 million.