I assume you must be talking about the skills that are NOT mentioned in the brief job descriptions 
Finding professional, experienced Software Developers, who are BOTH seasoned developers, WITH the required Aviation background knowledge & experience, must be difficult.
Tempting any away that are already on a career path in the aviation industry, to join a Games Dev Company, with very different development methods, on a limited time project with an uncertain future, might be a challenge.
It’s not a career path change I would ever have considered !