A big drop in airfares to several European destinations suggests airlines expect less trans-Atlantic traffic this summer.

Fares to select European cities from the U.S. have fallen dramatically — down as much as 68% — from January when airlines were charging steep prices, according to airfare shopping site Bestfares.com.

"We've seen real good drops," says Bestfares.com CEO Tom Parsons. "(Some who booked earlier) could be entitled to a voucher or refund for the difference."

The drop stems from airlines' aggressive pricing earlier this year in anticipation of robust travel that hasn't panned out, Parsons says. "Americans just weren't going to pay that kind of money," he says.(Read more...)