Yes:
Class 1 to 3 flights can be flown by Class 1 to 3 planes, as long as you have enough rank for both the flight and the plane.
Class 4 to 6 flights can be flown by Class 4 to 6 planes, as long as you have enough rank for both the flight and the plane.
Class 7 flights can only be flown by Class 7 planes, and obviously, you have to be Class 7.
Hope this clears things up. Oh, and it's in the operations manual
