One of the biggest mistakes day hikers make is assuming they don't need to plan for wilderness survival. After all, a hiker usually reasons, "I only plan to be out for a few hours. I'll be back long before sunset. There's no reason to carry more stuff than I have to." Unfortunately, hundreds of hikers die or become seriously injured every year by relying on this faulty reasoning. Wilderness survival requires planning ahead and making three basic assumptions.

The first assumption you should make is that you may be gone longer than you plan. If you're planning a day hike (a few hours or more), plan as though you'll be out overnight. Bring enough water for the hike, plus enough for the night and the following 24 hours. You may become lost or otherwise unable to get back to your starting point by sundown. Your body will already have lost a great deal of water from the exertion of the hike. The last thing you want is to find yourself stuck in the wilderness overnight with no water. It may seem like a hassle to carry so much water. However, your survival chances will increase exponentially if you have enough water to sustain you in case of emergency.

If you are stranded in the wilderness overnight, always assume that the temperature will drop. Even in the desert, overnight temperatures can be significantly colder than in the daytime. Exposure to cold or inclement weather can result in hypothermia and may even lead to death. Day hikers should never leave home without additional warm clothing. A sweatshirt, long pants, socks, and rainproof jacket or covering should be carried in a backpack. You also should consider carrying a thermal emergency blanket, which is lightweight and compact for easy carrying. They reflect heat, protect from weather and are fire-resistant.

The third assumption day hikers should make is that they may become injured. If you aren't prepared for the possibility of an injury, you could find yourself in trouble. Hikers should always carry a basic first-aid kit. Many hikers who have chosen not to carry one in order to save weight or space have regretted it later. Make sure the kit is fully stocked with band-aids, a sterile cleanser, gauze, adhesive tape and cloth bandages. Always replace items later if you use something from your kit.

Some other important things to remember:

* Take a buddy. Hiking alone is never recommended. It can be very dangerous, especially if you become injured. Hiking with a partner increases your chances of getting out of the wilderness alive if you get hurt.

* Take a cell phone. Dozens of hikers are rescued every year because they carried a cell phone. Having a cell phone may reduce your chances of injury or death by up to 50 percent.

* Make a plan. Be sure you know the area where you'll be hiking. If you haven't been there before, get a map of the area and mark the trail you'll take. Make copies of your map, and make sure every member in your group has a copy.

* Inform someone at home. Never go into the wilderness, even for a short time, without telling someone where you'll be, and when you plan to return. Leave a copy of your map with the person and explain your plans in detail. Tell them where you plan to leave your car. Arrange to call when you begin your hike and as soon as you return. This way, if you don't get back when you planned, someone else will know and have a good idea where you are.

Using your head ahead of time may very well save your life. It just pays to be prepared.