"It would have us testing Americans on airplanes that we all know are safe to be on," American Airlines CEO Doug Parker said during the carrier's Q4 earnings call.
Executives from Southwest and JetBlue echoed that sentiment, explaining that a domestic testing requirement would be too costly and pose logistical challenges. Centers for Disease Control and Prevention officials said Wednesday that the conversation is "ongoing" and that the agency is "actively looking at it."
The domestic testing would expand upon the administration's mandatory requirement for U.S.-bound travelers, which went into effect Tuesday. All travelers flying into the U.S. must now provide proof of a negative COVID-19 test, taken no more than three days before their flight, or they will be denied boarding.
In Thursday’s earnings call, American Airlines said this new requirement has hurt demand for its short-haul international flying, mainly to Mexico and other Caribbean beach destinations.
American Airlines CEO Doug Parker said his airline would work with the government should they mandate domestic testing, but expressed concerns such a requirement could disrupt already volatile demand.
"We certainly want to make sure it is something that wouldn't restrict demand," Parker said. "No one has talked to us officially about doing that -- and if they do we will do our best to make sure we stress how safe it is to fly."
Southwest Airlines CEO Gary Kelly said in an investor call that the focus should be on the continued rollout of the vaccine and asked, "why pick on air travel?"
"We don't have adequate testing capacity for the country in the first place," Kelly said. "It's just unrealistic to expect that we can efficiently and effectively do testing on a larger scale."
JetBlue President Joanna Geraghty echoed this point in an earnings call Thursday saying, "frankly, we're concerned that it would actually reduce the ability to some people who legitimately need to get test for health reasons."
This also comes as public health officials are warning Americans against travel. Dr. Anthony Fauci, chief medical adviser to President Joe Biden and the nation's leading infectious disease expert, said "It is not a good idea to travel, period."
"If you absolutely have to travel and it's essential, then obviously, one would have to do that. But we don't want people to think because they got vaccinated that other public health recommendations just don't apply," Fauci said during a CNN town hall.
ABC News' Mina Kaji and Sam Sweeney contributed to this report.