ABC says its new airline drama ”Pan Am” is not canceled, despite a seemingly alarming Tweet from cast member Karine Vanasse.

Ratings for the 1960s-themed show, which also stars Christina Ricci, have dropped about 50 percent, from 11 million viewers to 5.6 million, since its September 25 debut. The series is based on a real airline, which went bankrupt in 1991, and airs on Sundays 10 p.m. ET, around the same time as NFL games and the CBS series ”CSI: Miami.”

”We are not cancelling Pan Am,” an ABC spokesperson told on Tuesday, November 29. ”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.”

Vanasse, a 27-year-old Canadian actress who plays one of the flight attendants, said on her Twitter page hours earlier: ”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!”
She later corrected herself, Tweeting: ”Sorry for the confusion #PanAm fans; there are still 5 new episodes to air until February :)”
ABC recently released its 2012 midseason schedule, which shows that ”Good Christian Belles,” a new series starring Kristin Chenoweth, will air in the Sunday 10 p.m. time slot ”Pan Am” currently occupies, starting on March 4.
”Pan Am” is ”still in contention” for a second season, but an announcement about its future will not be made until the network’s annual upfront announcement, which takes place in May, the ABC spokesperson said.

Ashley Greene, known for playing the vampire Alice Cullen in the hit ”Twilight” films, is set to appear on ”Pan Am” for at least four episodes, beginning on December 4, ABC said in a statement, following a previous report that said she was hired for three. Her character, Amanda, is described as ”a debutante with a past connection to Ted,” the First Officer of the show’s main airline crew.