The Federal Aviation Administration's leader stepped down on Jan. 20, months after Elon Musk demanded that he quit. The move by Michael Whitaker means the FAA has no Senate-confirmed leader for one of the biggest crises in its history because he quit before Donald Trump took office. Whitaker ran the FAA for just a year but announced in December that he would step down on Jan. 20, as the new president was sworn in. Nobody has taken his place.