After high school, he joined the U.S. Navy where he was an air traffic controller, training and working at bases in the Philippines, Brunswick, Georgia, and Virginia Beach.
In June 1973, after being discharged from the Navy, and while waiting to transfer to civilian air traffic control, Shannon attended broadcasting school in Minneapolis where he graduated "with honors".
[3] In 1995, Shannon reported on false information posted on AOL related to the Oklahoma City bombing, provoking the harassment of Kenneth M. Zeran, a Seattle resident.
Zeran subsequently sued Diamond Broadcasting, Shannon's employer at the time, alleging defamation, false light invasion of privacy, and intentional infliction of emotional distress.
[3] In October 2000, Shannon was diagnosed with chronic lymphocytic leukemia, a slowly progressing cancer of the blood.