A strobe light should be an essential item for anyone travelling in wilderness areas. Unlike a mirror, a strobe is multi directional, works at night or in overcast, and is universally recognized as a "distress" signal.
Mirror flashes can be mistaken for accidental flashes from trash, and ignored by searchers.
There are many cheap strobes available from outdoor and camping stores, among the best is the single D cell powered one, a long life and cheap battery, but the downside is it is quite heavy for a small item, important if you are backpacking.
If you have one of the excellent USCG issued strobes, and the battery has died, it can be recharged, most Radio Shack stores will tell you how.
If you carry marker panels, draw the International Code patterns on the panel, as the way these are laid out can indicate everything from "We are OK" to "Serious Injury".
Kudos to Peoria 46 for the glint tape idea. I will be off to get some ASAP. Many police and air rescue aircraft are equipped with IR and thermal imagers and the glint tape could be a lifesaver, if other visuals are missed by search crews.
Never too old to learn.
