Are you sure it is not flying at night? That is how cargo operators like Farnair and Westair operate. They leave the outstation in the evening timed so they can reach the hub so the the freight can get sorted and put back on the aircraft. The aircraft then fly back home to the outstation, in this case SXF
where it arrives early in the morning 4-5 am in time for early delivery. The few times I have observed Farnair operations they tend to keep the same aircraft to the same routes. It nakes it easier for maintenance to plan ahead.
139, 306, 319, 320, 321, 332, 34A, AN2, AT4, AT5, AT7, 733, 735, 73G, 738, 739, 146, AR1, BH2, CN1, CR2, DH1, DH3, DH4,