Frontier says the passenger in question was on a Denver-bound flight early Sunday morning and was removed for not complying with repeated crew member instructions.
Several Los Angeles police officers were called in to escort the man off the plane.
Frontier requires all passengers to wear masks when flying.
There is no federal mandate requiring passengers to wear masks onboard a plane, but all major U.S. airlines put policies in place in recent weeks stating that passengers and crew have to wear face coverings in order to fly.
Exceptions exist for kids, passengers eating and drinking and for those with certain medical conditions.
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