When I was in the USAF, I spent some time riding in the helicopters at Sea Survival School. That convinced me to forget about the smoke flare - worthless The projectile flare for night will work only if the rescuer is looking right at it when you fire it, unless you have a pretty big one. A mirror is the best day attention getter if you're in the open and you have sunlight.
This is one reason why I carry a rather powerful laser pointer...
Now let me say first off that this is NOT to be used in anything other than an actual, life or death type survival setting!!
A laser pointer can be seen by aircraft miles away, day or night... Currently the FAA and local authorities have had a hard time with idiots flashing these lasers at aircraft, and I do believe it's a felony to do so.
However, if your family is sitting on the roof of your house (which you accessed with a hatchet THROUGH the roof) and the water is rising quickly, the bloated bodies of your neighbors are floating by, and another storm is on the way..... Helicopter after helicopter pass you by... something a like a powerful blue or green laser might be the ticket to get your family out alive. Disaster settings is the primary idea here...