Seats are limited at these fares, and certain flights and days of travel may be unavailable, the company said.
Republic Airways Holdings announced Oct. 2 that it was selling Frontier to Indigo Partners L.L.C., a Phoenix firm that invests in low-cost airlines, including Miramar, Fla.-based Spirit Airlines, Singapore-based Tiger Airways, and Hungary's Wizz Air.
After the deal - valued at $36 million in cash, plus assumed debt - was announced, Indigo cofounder William Franke said that his firm wanted to make Frontier operate more efficiently to ensure it could offer lower ticket prices to leisure travelers looking for a bargain.
"There will be a push to be more efficient so that the airplanes fly more hours, we better manage maintenance, and we work on how to have fuel savings as we fly," Franke told Reuters news service. "In general we would be focused on the ultra-low-cost model."
An Indigo spokeswoman said Wednesday that Franke would not comment on plans for the two area airports where Frontier flies - Trenton Mercer and New Castle near Wilmington - until the deal closes in December.
Franke is the former chairman of Spirit Airlines and former CEO of America West Airlines, which merged with US Airways Group in 2005.
"By adding these new routes to Charlotte and Cincinnati, Frontier continues to strengthen its network for travelers in the Mercer County region," said Brian Hughes, executive of Mercer County, which owns the Trenton airport.
"As we gear up for the grand reopening of an improved Trenton Mercer Airport on Nov. 8, we eagerly welcome back Frontier, its loyal customers, and all those who are excited to fly Frontier," Hughes said.
The Trenton airport has been closed to commercial flights since last month for a runway upgrade. Military and corporate jets still take off and land. The large runway will reopen Nov. 8.
Frontier's strategy has been to use a mix of smaller secondary airports, where landing fees are lower but are close to large metropolitan areas, as well as flying from some major airports.
Frontier, whose planes' tails have pictures of animals, operates routes two or three times a week, instead of daily. That requires fewer crews and planes are full.