Five main British Antarctic Survey stations were occupied throughout the year: Faraday and Halley (the two geophysical observatories), Signy (the main biological station), Grytviken (a multidisciplinary sub-Antarctic station and centre for the Offshore Biological Programme) and Rothera (the centre for earth sciences programmes). During the 1979 winter, routine programmes were maintained by 72 men who also made preparations for the forthcoming summer season. The two BAS ships, RRS John Biscoe and RRS Bransfield, with assistance from two Twin Otter aircraft relieved the stations, as usual, and assisted summer field workers. Valuable assistance was also given by the ice-patrol ship, HMS Endurance. John Biscoearrived in the Antarctic late in the season, having been delayed while her refit was completed. (The ship, which has been in continuous service since 1965, had undergone major repairs and modifications to ensure her continued suitability for Antarctic service and to increase her usefulness as a floating laboratory.) All stations were relieved without difficulty, but, because of this season's tight shipping schedules, Rothera was not reached by sea until the end of March 1980, although it had been relieved by air at the beginning of January. At Halley, the season was overshadowed by the death of the base commander, Miles Mosley, in an accident involving one of the aircraft. A second man was injured but made a complete recovery. At Faraday, good progress was made with the programme of modernization. Part of the main building was demolished and replaced by a new extension, and a desalination plant and new inflatable fuel tank were brought into use.