Hi Matt,
when you check with AMA about a required membership, please also ask for third party liability insurance and whether it comes with AMA membership.
All German third party liability insurances, also the one I get from my German Federation, explicitly exclude coverage of model airplane activities in the US. In that case, assuming that Polish Insurances have the same policy, your fellow pilot from Poland may not be insured prior signing in to AMA, for instance when doing practise flights prior the competition.
Last time I competed in the US was in VSC in 2000 and signing in to AMA was possible at the circle. But 19 years have passed and I would like to do the NATS as well one day.
So please check with AMA and report back to us in this forum because it is of interest to many here over the pond.
Thank you!
Christoph