Case Study III - another real-life example where mirror signaling accuracy was not so great ...

An article in a US Coast Guard Auxillary publication from Oct 2009
(October 2009 issue of "Northwind", page 10, downloadable here)
http://resource.d11nuscgaux.info/northwin/2009/09OctNW_Web_View.pdf)

reported on their search-and-rescue exercise (p. 10, per protocol on bottom of p. 9), where one group was in a boat, and another in a search plane. The group on the boat were to signal to the plane via signal mirror. The plane spotted the boat by its markings, and made two passes. To quote the article:

"Only one mirror flash was observed during this approach, even though the sun angle was good for signaling"

Only one flash? With the people on the boat healthy, not in distress, expecting the plane in a narrow time frame, the plane expecting a flash from the boat, and two passes?

Not so good. No indication of the type of signal mirror used, but I'm thinking the boat team needed all the advantages they could get.