Before the flight, the crew found that one of the two main power generators was defective and had been so since 6 September. Also the mechanic who had inspected the aircraft was unable to repair it. In the Norwegian jurisdiction an aircraft is only allowed to take off if it has two operable sources of power. Also the aircraft's Minimum Equipment List required two operating generators. The first officer decided that he would run the auxiliary power unit (APU) throughout the flight so that the flight would have two sources of power and therefore be allowed to leave.