Unfortunately the “Content.XML” trace was a red herring too. It worked for me for a few hours, then the problem came back as per usual. I’m investigating this kind of issues on and off since months and this is really time consuming, so I could use some help:
Do you guys have “Use generic plane models…” set to “OFF” for either AI traffic or multiplayer (or both)? If so, does putting both back to “ON” let you load a “problem airport” (at least for a while)?