"Roy Smith" wrote in message
...

I need to fly around or over Potomac's airspace. So, I might start by
asking some questions:

"If I climbed up to 9000, would that help?"

Center comes back with, "Sorry, you'd need to get up to 13,000 to stay in
Center airspace on that route, can you make that?" (I'm making that up,
but
it sounds plausable).


As I recall from a conversation with a Washington ARTCC controller some
years ago, the forerunner of Potomac approach went up to either FL180 or
FL240.