The Federal Aviation Administration has issued a nationwide ground stop for all U.S. airports following a “communication issue.”   While authorities have said they do not believe this issue is the result of a cyber attack, DHS Secretary Markwayne Mullin said he is not ruling anything out.  Airport staff are telling passengers to head home, or to find housing, releasing luggage from planes as there is no information as to when flights may resume.  This is only the third time in history the FAA has issued a nationwide ground stop.