Want to make sure you get a decent seat on your next flight? How about a coveted exit row seat? If so, it may cost you an extra $10 to $30 round trip if you're flying on AirTran Airways.

The discount carrier recently began charging extra fees if fliers using its lowest fares want to pick where they sit in advance.

Previously, passengers using the carrier's sale or discount coach fares couldn't pick seats until they checked in for their flights --- either in person or online. They still have the option of doing that with no extra charge.

But AirTran fliers using those fares now also have the option of paying an extra $5 each way to reserve a seat at the time of booking. They can pay $15 extra each way for an exit row seat. Those seats, adjacent to emergency exits, have more legroom and often fill up well in advance.

An AirTran spokeswoman said many customers are glad to have the option, but Atlanta lawyer Jay Barber doesn't like the extra fee. Most big airlines don't charge for any advance seat reservations, and last week he took Delta Air Lines to Philadelphia rather than pay extra to reserve a seat.

"I'm just appalled by this and told them so," said Barber, an AirTran regular.

AirTran's seat fees don't apply to higher fare categories; those fliers, along with members of the frequent flier corporate travel programs, can continue to reserve seats at the time of booking with no fee attached, AirTran spokeswoman Judy Graham-Weaver said.