The Boeing B-17 Flying Fortress was a four-engined heavy bomber developed in the 1930s and primarily employed by the United States Army Air Forces (USAAF) in the daylight bombing campaign of World War II against German industrial and military targets.

The Messerschmitt Bf 108 Taifun (German for "typhoon") was a German single-engine sports, touring and communications aircraft developed by Bayerische Flugzeugwerke (Bavarian Aircraft Works). The experience gained by Messerschmitt in developing this aircraft led to the most important German fighter of World War II, the Messerschmitt Bf 109.

Many USAAF aircraft landed in neutral Sweden during WW2. The Swedish authorities arranged to buy many of these from the US, to supplement their limited and ageing aircraft stocks. The B-17 Flying Fortress was selected for conversion to an airliner, and Saab undertook the work.