I imagine it means that the "combat area" will be larger for planes then when your on the groud. ie.you can fly further with a plane without leaving the zone and being hurt.
You appear to be spot on ...from the ign movies iv seen there are two red zones one darker than the other the jets and i assume choppers can fly into the lighter red zone but not the dark red zone.
was lucky, got a new PC for two week's ago
My pc is 1 and a half years old and still belting along fine it shall!! play bf2 no prob