Just did a search to verify the 400-foot limit. (That’s how I found out I asked this before.) Apparently the real reason there are no planes is the budget.
So apparently, aircraft can only be used for dogfights and airstrikes and action scenes. They’re completely useless for getting from Point A to Point B. The only aircraft that are not useless for getting from Point A to Point B are airliners that fly at Mach 0.85, so they’re much too fast for story lines that often depend upon characters taking a long time to get somewhere and towns like Defiance being isolated by distance. Little airplanes that fly at 130 mph and take days to cross the country don’t exist and have never existed. And even if little airplanes existed, it would cost hundreds of dollars to rent one for a day’s shooting.
So that explains why there are no airplanes or helicopters. But how can the writers be so bad at science? No, really. I understand that most people are not scientists. I understand that even writers and producers who are good at science and make every effort to be accurate, flub things up. When watching a work of fiction, sometimes you have to suspend your disbelief. But this 400-foot radiation layer… That’s really poor writing.
So the fact having been established, is it AGL or MSL?