SAS bought Braathens in 2001, and from the following year, only SAS flew the Oslo route. Within months, Norwegian started a low-cost route to Gardermoen. SAS Commuter took over Norwegian's regional routes in 2003. The Norwegian Meteorological Institute closed its office at the airport in 2003 and all meteorological observations have since been carried out by Avinor. In 2004, SAS and Braathens merged to form SAS Braathens. The airline changed its name back to Scandinavian Airlines in 2007. The international arrival section was expanded with in 2005, followed by an extra story over part of the terminal, used as offices and allowed a doubling of the size of the duty-free.