<div>BREAKING: In an extraordinary move made only one other time since 9/11, the FAA orders ALL flights nationwide grounded, bringing departures across the U.S. to a halt.</div><div><br></div><div>The Federal Aviation Administration is directing all departing aircraft to remain on the ground until further notice, citing safety concerns.</div><div><br></div><div>International flights arriving in the U.S. will be handled on a case-by-case basis as questions mount over what triggered the sweeping order.</div><div><br></div><div>The FAA has not publicly detailed the cause of the emergency action.</div><div><br></div><div>Download the Fox News app or go to FoxNews.com for more.</div>