UFO over active USAF B-52 base, controllers ask civilian pilots to identify...

I was working as a non-scheduled, on demand, commercial pilot for a company that was based in Wenatchee, WA.  I haven't checked the actual date in my logbook that this occurrence happened yet, but I estimate that it was late fall in 1992 (I'll verify).  Another pilot and I were paged at roughly 11:00 and informed that we would be picking up a United Airlines maintenance crew and tools at SEA and flying them to GEG to repair a 747, standby and then return them if they completed their task.  We were wheels up before 00:00 from EAT, picked up the maintenance crew/tools by 01:30 and arrived at GEG estimated 03:00.  After standing by for roughly 1.5-2.0 hrs, we were released to return as the crew would not be able to complete in a known duration.
It was my leg as captain and we departed approximately 04:30-05:00.  It was a very low ceiling inversion that was only 200-300 ft and CAVU weather above. Immediately after departure, GEG tower informed us to contact Fairchild AFB instead of the usual/expected issuance of departure frequency.  The first officer contacted Fairchild and immediately after affirmation they advised us of traffic at 6:00 type/altitude unknown, unusual call in that we it was not just IMC conditions, but we were transiting over an active military airfield.  Several call and responses were delivered as they reported traffic rapidly moving from the 6 position to obviously overtaking us on the right side of out aircraft.  First officer didn't see until it was at out 3  position out of the eyebrow window above his seat.  At this point it was estimated to be several hundred above our altitude (we were still in a climb) and moved at such a rapid rate, later conversation between us confirmed that no typical aircraft could move at this rate.  When the UFO was off our nose and above us and in plain view, it literally went vertical and was gone in what we estimated to be 5 seconds.
My first officer was very disturbed by this event and pursued getting civilian and military ATC tapes, but the military apparently doesn't need to release these transmissions unless requested from an entity other than a civilian.  He was a very devout Christian and had a difficult time post incident accepting what we had witnessed that morning.
This was not my only incident, just one of them.