Pan Am actress Karine Vanasse took to her twitter account to inform all her followers that ABC is cancelling her show. 

Well, we received THE call, #PanAm is only coming back for one more episode after Christmas. But up to the end, we’ll give it our all !

We will update this page as more information gets released.
UPDATE: There is a possibilty the show is still safe.
Here is the statement from an ABC rep: 

Nothing has changed. We are not cancelling Pan Am. We are still in production and will continue to be in production finishing the original 13 episodes plus one more additional one. We have one more original episode this coming week, Dec. 4 and then will return in January with new episodes, airing all of them. Pan Am is still in contention for next season.