At one time prior to the 1979 revolution, Iran Air was one of the worlds most progressive airlines. It has been a long road back to viability since then. Because of embargoes, the airline has prohibited from obtaining new western aircraft forcing it to operate an elderly fleet of Boeing 727s, 737s, and even 747SPs, as well as early Airbus A300-B4s. Recent thawing of relations with the west have allowed leases to be taken up of late model A320s.