You have my vote.

It seems as though all the soldiers need training in parkour.

After further testing, this issue seems only to be able to be replicated while using the blackhawk. It does not vibrate if the rear wheel or the front wheels are on the metal grating surrounding the helipad. All three wheels must be on the helipad in order for it to vibrate.

So it may only be an issue with the blackhawk, not the helipad.

I have tested this on every helicopter, and only the Ghosthawk has instant bouncy-wheels when landing on the helipad.

Thanks Gekkibi for confirmation.

I'll look around for more helipads, and see if it is unique to only this one.

EDIT:

On my quest of finding more helipads, I randomly decided if I could land on a pier. Upon landing, the ghosthawk started exhibiting the bouncy wheels again.

The problem seems to be that the ghosthawk's geometry somehow interferes with specific terrain types.