WASHINGTON — Cabinet secretaries, top congressional leaders and an exclusive group of senior U.S. officials are exempt from toughened new airport screening procedures when they fly commercially with government-sanctioned security details. New heightened security procedures by the Transportation Security Administration, which require either a scan by a full-body detector or an intimate personal pat-down, have spurred passenger outrage in the lead-up to the Thanksgiving holiday airport crush. The senior government officials can opt out of such measures if they fly accompanied by government security guards approved by the TSA. The agency would not explain why it makes these exceptions, but...