If it's a solid casting - I use a couple of screws into it and mount it all onto some epoxy (Including in the screw holes).
If it is hollow and large enough, I drill a large hole in the middle of the base (If there isn't one there already) and put a couple of pieces of hardwood inside where the screws mentioned above will go - then do the same thing.

Works for me when I use a figure.

Nowadyas, I prefer to go to tinted canopies and leave the pilot figure out altogether but I am also not a "scale" builder.