If something goes wrong, the information you provide your emergency contact will be the starting point for the information Search and Rescue groups use to look for you. Much of this information will remain the same for multiple trips and some will be trip-specific. The items I list won't be comprehensive, but rather a selection of items from an online trip-report form that was created for just this purpose. Thus, you can prepare in advance a packet with most of the information and just update the trip details each time you head out.
- Name, age, sex, height, weight, hair and eye color.
- Any medical conditions, medications, or allergies?
- A recent picture of yourself.
- Are you a skilled hiker, a novice kayaker, regularly climb 5.13 trad or stick only to trails?
- How much first aid knowledge do you have? What about navigation and survival knowledge?
Your emergency contact can always call the local emergency number, but contact information for the Sheriff's office (or appropriate local agency) where you'll be starting your hike may be more useful.
Are you taking a car, bus, train, plane, or llama to the trailhead? For personal vehicles, the make, model, color, and license plate number are helpful. (If you take a bus, the driver or other passengers might remember you.)
A map with your expected route highlighted is most convenient. Alternate routes, expected campsites, and potential side trips should also be noted. You should have a rough idea when you'll start, when you'll return, and generally how quickly you cover ground.
What navigation or signalling equipment do you have? If a PLB, is it registered? If a cell phone or two-way satellite messenger (InReach, Spot, etc.), what type is it and what's the contact information? Is there a URL where it displays its location?
You don't need to list every item, but larger items are easier to spot and smaller items may be found by searchers. An easy way to inventory is to simply lay everything out on the floor and take a picture. While you're doing this, it's also good to note your shoe size, model, and include a picture of the soles.