Below I'm listing Doug Ritter's top '10' list of survival items that he presented on a radio show a while back. Now, people can argue long and hard about the details and order of each, but I for one whole-heartedly agree that a mapping GPS w/ spare batteries AND a PLB can be true lifesavers if the worst happens.
So many people get into trouble because they simply get lost and can't find their way back to a key location. Yes, map & compass navigation skill are important and EXTREMELY useful, but when the stuff has hit the fan I'd much rather rely on a mapping GPS for navigation than a map & compass. A good mapping GPS with an on-board electronic compass makes navigation so simple that quite literally an 8-year old can do it.
If the time has come where you need to stay put and call for help, then a PLB will - without much question - bring help to you. Yes they are expensive, but how much is your life worth to you???
Downsize/trim your key survival gear so that you can keep it with you at ALLLL times - even when just stepping away from the campsite to do some personal business. It won't help you if you don't have it. Accidents don't come with a 3-minute warning light.
As others have said, pre-trip planning, preparation, and notification are keys to keeping you safe and making sure you get home.
1. Navigation - a mapping GPS w/ spare batteries, or secondarily a map & compass, AND the knowledge to use them together
2. Knife - one-hand opening
3. Fire starter & Tinder
4. Water & water purification
5. Whistle
6. Signal Mirror
7. Duct Tape
8. Shelter - large garbage bags or AMK Heat Sheets blanket
9. Flashlight or Headlamp - LED, lithium battery, with constant-on switch
10. Sunscreen and/or Insect Repellent
11. Personal Locator Beacon