Try to picture it: A fluke will dive when it is weighted, now when it is weighted on an angle, ie, not straight down, the fluke wants to get out towards the thing that pullin it, not go down. SO, steeper the inlcine, assuming that fluke is always placed 90* to horizontal, there is less snow holding it in for a given placement, less for it to move through and out. (nonscientist grasping at high school physics and math )
You'd hafta have pretty unconsolidated pow for this to occur, I'd imagine.