Several U.S. airlines announced Monday that masks are now optional on their aircraft -- Delta Air Lines, American Airlines, United Airlines, Southwest Airlines, Alaska Airlines and JetBlue.
Delta Air Lines says it is making masks optional, and warned travelers they "may experience inconsistent enforcement during the next 24 hours as this news is more broadly communicated."
"Given the unexpected nature of this announcement, please be aware that customers, airline employees and federal agency employees -- such as TSA -- may be receiving this information at different times," the airline said.
United Airlines said in a statement that "masks are no longer required at United on domestic flights, select international flights (dependent upon the arrival country's mask requirements) or at U.S. airports."
Alaska Airlines similarly said face masks are now optional and asked for passengers to be considerate.
"While we are glad this means many of us get to see your smiling faces, we understand some might have mixed feelings," the airline posted on its website. "Please remember to be kind to one another and that wearing a mask while traveling is still an option."
American Airlines said "face masks will no longer be required for our customers and team members at U.S. airports and on domestic flights."
"Please note face masks may still be required based on local ordinances, or when traveling to/from certain international locations based on country requirements," it said.
Alaska Airlines said some of its passengers who were banned from the airline during the duration of the mask policy will continue to be prohibited from its planes.
Southwest Airlines, meanwhile, said on its website that employees and customers could "choose whether they would like to wear a mask, and we encourage individuals to make the best decision to support their personal wellbeing."
It also said it would "continue supporting the comfort of those who travel with us by offering additional layers of protection."
JetBlue said in a tweet Monday that mask wearing will be optional within the United States. "While no longer required, customers and crewmembers may continue wearing masks in our terminals and on board our aircraft," the company tweeted.
Meanwhile on the ground, Amtrak said it will no longer require face masks for passengers and employees.
Last week, the U.S. Centers for Disease Control and Prevention extended the mask mandate through May 3. The masking requirement applied to airplanes, trains, and other forms of public transportation. A Biden administration official says the order is no longer in effect while the ruling is reviewed.
- CNN's Gregory Wallace contributed to this report
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