一直被问到国内运行规范C0039当中R、F、P、A机场的关系。比如，R机场是不是能当A用。以前都觉得是理所当然，没去找过出处。现在这个文件里说明了。

For Part 121 Operations, a Certificate Holder May Use a Regular, Refueling, or Provisional Airport. For part 121 operations, a certificate holder may use any regular, refueling,or provisional airport as an alternate airport, provided the airport is authorized for the type of aircraft being used. There is no need to dually（双重） designate an airport as an alternate for a particular aircraft type, if that airport is already authorized as a regular, provisional, or refueling airport for that aircraft type.

所以R、F、P机场本身就能作为A用。不需要重复说明。签派放行可以放行到R、F、P中的任何一个。

不过国内的法规里到没找到这么说过。