What fire is to nighttime rescue, smoke is to daylight. The best way to get the attention of passing planes or helicopters is to do it the way the Native Americans did it, and how Boy Scouts are still taught to -- make a smoke signal. Once you get a good fire going, throw some green boughs (or wet) on top of the fire. This will create a tremendous amount of thick, white smoke that can be seen for hundreds of miles. When you get a good smoke plume rising, use a jacket, sleeping bag or blanket to signal. If there is water around, wet the fabric some. But if there's no water, you can still signal with it. Cover the fire with the blanket for about a second and pull it off three times in a row, making sure not to disturb your fire too much. This will send three distinct puffs of smoke into the air, which is the international signal for trouble. Keep repeating the three bursts of smoke until you're rescued.