Which airline, with the abbreviation DAT, operates two daily flights to Oslo Airport, Gardermoen? 
Stord Airport, Sørstokken:  Danish Air Transport operates up to two daily flights to Oslo Airport, Gardermoen. Danish Air Transport: Danish Air Transport A/S, often abbreviated DAT, is a Danish airline headquartered in Vamdrup, Kolding Municipality, operating scheduled and chartered passenger and cargo flights.
Danish Air Transport