Frontier Airlines is selling a social distancing upgrade for $39. Some in Congress are appalled.

WASHINGTON - Democrats on Capitol Hill are blasting a plan by Frontier Airlines to sell a social distancing upgrade to passengers concerned about the novel coronavirus.

Frontier says that starting next week, customers will be able pay $39 to guarantee a spot on the plane next to an open middle seat as a way to maintain social distancing during the coronavirus pandemic

Other airlines are taking similar steps to spread passengers out, but they are not charging fees.

In a news release announcing the upgrade, Frontier said the idea builds on requirements that crew and passengers wear masks onboard its planes.

"While we believe the best measure to keep everyone healthy is to require face coverings, for those who want an empty seat next to them for extra peace of mind or simply additional comfort, we are now offering 'More Room,' " Frontier Chief Executive Barry Biffle said in a statement.

Democratic lawmakers condemned the idea.

Rep. Peter DeFazio, D-Ore., chairman of the House transportation committee, said he wants the airline to rethink a move he called "callous profiteering."

"I find it outrageous that an airline sees the imperative for social distancing as an opportunity to make a buck," DeFazio said in a statement. "Frontier's decision to charge passengers to keep middle seats empty is capitalizing on fear and passengers' well-founded concerns for their health and safety."

During a Senate Commerce Committee hearing Wednesday on how the aviation system is dealing with the global pandemic, Sens. Maria Cantwell, D-Wash., and Amy Klobuchar, D-Minn., both spoke out against the fee.

"I don't think it's appropriate for some passengers who can't afford to pay an additional charge for a seat to be less safe than other travelers," Klobuchar said.

She asked Nicholas Calio, president of Airlines for America, a major trade group, what should be done. Calio was quick to point out that Frontier was not a member of his organization and said none of its members were charging for such an upgrade, nor would they be likely to.

"I don't anticipate anything like that," Calio said. "Our members are making every effort to keep passengers as separated as possible."

In practice, aviation industry leaders say it has been fairly easy to follow social distancing guidelines because passenger numbers are down more than 90 percent from their typical levels. But airlines have advertised efforts to keep middle seats free as a way of ensuring passengers can spread out within the normally tight confines of economy class.

Frontier says it is taking other steps in line with the rest of the industry to clean planes using disinfecting fogging devices and emphasizing the air filtration systems on its planes.

Those filters are standard on modern planes, but there is evidence they can't completely prevent disease from spreading within aircraft cabins.

The pandemic has sparked other battles over passengers’ rights, with several airlines facing lawsuits alleging they violated federal rules that require them to offer cash refunds rather than vouchers when they cancel flights.