We were sitting on the porch when I noticed a falcon-like bird in a glide to my left.  Using binoculars I was not immediately able to identify it as we were looking toward the sun angle.  The bird turn toward us, remaining in a glide, and even more into the glare so I began taking what photos I could due to severe backlighting, making direct observation difficult.  The entire observation time was approximately 20 seconds and the bird was never observed to flap in that time.  It sailed over us at perhaps 100 feet high and disappeared from view.  At the time we easily ruled out PEFA due to a number of things including lack of a mustache.  The bird's size and shape easily ruled out AMKE.  At the time I was assuming it must have been a PRFA and the photos would be defining.  However, I took several days to process the photos and once I looked at them I ruled out all falcons and arrived at an ID of a MIKI.  The face and throat were whitish.  The breast and belly a muddy gray-brown color with paler vent.  The primaries were dark and P10 was very much shorter than the longest primaries with a clearly defined white patch at the base.  The trailing edge of the secondaries was dark.  The underwing was mottled brown-gray with no obvious banding or other marks.  The tail was dark with narrower pale horizontal bands.  I actually had to ponder the photo a bit before it struck me as a MIKI.  I have fairly extensive experience with the birds in Virginia and reviewed my own photos (historic) as well as several references to feel solid in the identification.  The bird was not heard to vocalize.  Based on plumage this is an immature bird - I don't see any obvious signs of primary molt and presume this bird to be a year old and of an age group known to wander.

See prior notes - photos eliminated all falcons from consideration

My own experience primarily along with my own extensive photos (historic).  I also looked at Hawks in Flight by Dunne, Sibley and Sutton.

Fairly extensive experience watching MIKIs during breeding season, including a nest and during migration.