Gas prices are expected to continue to fall in 2015, which could mean airlines might start lowering fares. The big question is "When?"

"It seems that airlines are a little bit hesitant to drop prices right away, because if prices do start to reverse course, then they will be stuck with those tickets that they will actually lose money on," said Stephanie Dembowski with AAA.

Dembowski said while it’s difficult to anticipate when airlines might transfer those fuel savings to passengers, she anticipates it will happen should oil prices remain low.