EWING -- Frontier Airlines will begin flying larger, more fuel-efficient planes out of Trenton-Mercer Airport this spring.

The low-cost carrier is replacing its Airbus A319s with A320s, a move that will bump the number of seats from 150 to 180 or 186.

"It allows us to better match capacity to the demand out of the Trenton market," spokesman Rich Oliver said Tuesday. "The number of flights will stay the same ... so it allows us to fly more people on the same schedule."

The transition will begin March 21 with one daily flight and by April 21, the larger aircraft will be used on all routes flying to and from Trenton-Mercer.

Oliver says Frontier will rotate between using A320s, which seat 180 passengers, and the newer, 186-seat A320neos.

The single-aisle A320neo -- or "new engine option" -- incorporates an engine that uses less fuel and sharklet wing tips that help reduce fuel needs.

Oliver said no changes had to be made at the airport to accommodate the larger planes, but extra flight attendants were required. The airline recently added 100 flight attendants to its crews in Trenton and Philadelphia.

"We know that several Frontier routes from Trenton-Mercer fly at maximum capacity and are completely sold out, which is positive news for the airline," county spokeswoman Julie Willmot said. "Increasing the number of available seats will give consumers greater opportunity to get where they'd like to go."

The current destinations out of Trenton-Mercer are Atlanta, Charlotte, Chicago O'Hare, Detroit, Ft. Lauderdale, Orlando, Punta Gorda, Raleigh and Tampa. The schedule runs through June 6.

Cristina Rojas may be reached at crojas@njadvancemedia.com. Follow her on Twitter @CristinaRojasTT. Find NJ.com on Facebook.