After further investigating into available models, everything turns out to be well designed. (wheels are also shifted to match the surface).
From this place I can only ask (feedback) to include Land_Wreck_C130J_3 that would be the destroyed plane, but would have tires on both sides on the same level and the stair piece was lowered a little, to allow placement without need to change the roll.

Original post below:
Stair for C130 and C130_cargo types, will always float if placed in straight position.

In vanilla it may be that wrecks are sunken into the surface, to imitate crash, which would make stair touch the ground, but from my experience it is hard to achieve positioning of mentioned models in a way, in which they would benefit from such stair placement. If you would lower the "plane nose", the chassis would not touch surface properly instead.