One of the guys I fly with in a sheriff's aviation unit hit upon an interesting signal device. He was out in the mountains on a dark a$$ night, no moon, little illumination, looking for lost hikers. He was on NVGs. The lost hikers heard the helo coming and called 911 on their cell phone. They were just too tired or incompetent (they got lost after all) to direct the helo in any meaningful way. They had no flash lights or fire making material. So my buddy had him turn his cell phone in the direction of the aircraft noise. That little LCD screen blossomed in a bright flash on the goggles. He said it was similar to a mirror flash in the day. Lost guys rescued. Some of you have lots of hour on NVGs. Tuck this story away and someday you might find it useful on a civilian assist rescue or as a victim yourself. Remeber, even if you don't have cell coverage for a call, you can always turn it on and flash it like a mirror in the darkness.