Are there additional electrical grounding methods besides static wicks?
Many aircraft tyres conduct electricity which also dissipates charges.  The compound contains "carbon black" or graphites.

In the special case of helicopters using a hook to pick up a load from a hover, the wise ground handler will use a rod on the end of a grounded cable to earth the charge.  Helicopters can build up a lot of static and many a ground handler has been left with smoking underpants by not heeding this advice.