Frontier Airlines
The same equity firm that helped turn Spirit into a fee-heavy ultra low-cost carrier could do the same with Frontier Airlines. Tumblr

Starting this summer, Frontier Airlines' passengers will pay a $100 fee for overhead bin carry-on bags at the gate.

If they pay in advance, it's $25. There's a way to avoid the fee, however. Customers who book at Frontier's website will be exempt from the fee. Frontier's elite-level members of its EarlyReturns frequent-flier program also won't have to pay the fees. The carrier said carry-on bags that can fit under seats ride free.

Travelers purchasing tickets from third-party vendors such as Orbitz are subjected to the new fee.

Frontier is the third big U.S. carrier -- behind Spirit and Allegiant-- to add a carry-on baggage fee. In addition to that fee, Frontier Airlines will also charge non-elite passengers and those who don't book on its website $1.99 for coffee, tea, soda, and juice, though coffee refills are free. They will also only accrue 25 percent of the normal frequent flier miles.

“With this change, we are ensuring that our most loyal customers – Ascent and Summit level members of EarlyReturns, those who book Economy, Classic and Classic Plus tickets, including all customers who book through, will have more space onboard the aircraft for their carry-on bags,” Frontier CEO David Siegel said in a statement released on Wednesday.

Frontier said the changes are in response to complaints from its top-tier fliers about overhead storage bins filling up before they can stow their carry-ons. Some industry watchers, however, also see the move as a bid by the carrier to drive more ticket sales to its website.

In November, Spirit Airlines raised its fee to $100 for carry-on bags at the gate.

"I know this is hard for a lot of us to swallow, but airlines have the right to charge as they please," aviation consultant Michael Boyd told USA Today about the growing trend of airlines tacking on extra fees. "They are not a public service."