Herman, it has happened, but it is rare. But this is missing the point. Look at the statistics. Where and how do most aircraft crashes happen? As Aksar says, they mostly happen near airports on takeoff or landing, so rescue is quick and effective, right? Not necessarily. Again, as I have traveled extensively all over the world, I rely on my personal experience. There are many airports and even major cities around the world where you can be in rugged and remote terrain within 5 or 10 miles from the airport. Many countries do not have effective rescue organizations, and their hospitals would have difficulty with a mass casualty situation. So what are you trying to survive? Not a trek through the wilderness for days or weeks, living off of the land, but the first few hours until rescue. First aid, shelter, and signaling are very helpful in such situations.

You need to get out of the aircraft to survive, as most do burn. There may be injuries, to yourself or others. My bag does have trauma supplies such as tourniquets, compressed gauze and triangular bandages. They do not take up much room and are primarily focused on self aid, not dealing with a large number of casualties.

Also remember the rule of "3s": 3 minutes without air, 3 hours without shelter, etc. Along with injuries will come shock, and many aircraft incidents occur in bad weather, so shelter would be helpful. Many countries in the developing world will not be able to reach a crash site in rugged terrain for several hours. Winter in the mountains can be deadly in less than a few hours. The people most likely to reach you first are civilians, not professional first responders. You need to be able to take care of yourself for a while, so having some sort of shelter, such as a heat sheet, is useful. Dressing for the weather is a bit more difficult as you are sitting in a climate controlled aircraft for an extended period, it can be very uncomfortable. Carrying the appropriate clothing is not too burdensome. You just need to get it on before the aircraft goes down if possible. In winter travel, I generally have a wool overcoat that I carry. I extends down to my calves and has a collar that can be raised. Wool also does not burn and provides some protection. It makes a good pillow as well.

Yes, we all know that TV and movies are not real, Herman.