The basic design of the SAS has remained almost unchanged in 50 years of use and all Soyuz launches carry it. The only modification was in 1972 when the aerodynamic fairing over the SAS motor nozzles was removed for weight-saving reasons as the redesigned Soyuz 7K-T spacecraft carried extra life support equipment. The uncrewed Progress resupply ferry has a dummy escape tower and removes the stabilizer fins from the payload shroud. There have been three failed launches of a crewed Soyuz vehicle, Soyuz 18a in 1975, Soyuz T-10a in 1983 and Soyuz MS-10 in October 2018. The 1975 failure was aborted after escape tower jettison. In 1983, Soyuz T-10a's SAS successfully rescued the cosmonauts from an on-pad fire and explosion of the launch vehicle. Most recently in 2018, the SAS sub-system in the payload shroud of Soyuz MS-10 successfully rescued the cosmonauts from a rocket failure 2 minutes and 45 second after liftoff after the escape tower had already been jettisoned.