rafowell ... thanks for posting some very interesting data on the visibility of mirror flashes. My takeaway is that I can count on about 20-25 miles for a mirror flash, but i might get lucky with much greater distances if the observer is in the same direction as the sun.

Incidentally, I have some independent confirmation from the Coast Guard. I asked one of their helo pilots what type of rescue signal they recommend. He told me that mirror flashes were by far the most effective signal on sunny days, and could be seen over 20 miles.

Your data have persuaded me that there is some value in having a larger mirror, such as a 3 inch x 5 inch device.

cheers,
Pete2