Kayak Lake Mead's Map & Compass
Practical Applications of Using the Altimeter

...Three things to keep in mind are; ( 1) Get a good one; on the rare occasions when you use an altimeter you’ll want accurate readings, (2) Its readings will vary with local atmospheric pressure changes; so occasionally reset it during your trek at known elevation positions such as on hilltops, and (3) if you are ascending or descending very fast your altimeter will not ”keep up with you”, there will be a lag time; stop, wait a couple of minutes and then read it. 
1. Descending a Steep Mountain in Limited Visibility Using Altimeter and Compass:

You are at the top, at WP 4, at 9960’, and in the clouds and descending to WP 5.  Visibility is 100’.  Your altimeter works just fine.  You need to know where WP 3 is; because that denotes the ridge leading to WP 5.  I don’t think time and distance will be a lot of help in finding WP 3; however always estimate the distance and keep an eye on the time you spend moving.  It is just too steep, too foggy, and there is just too much brush and too many rock bands to contend with; to have any realistic idea of your pace down.

Notice the elevations shown on the map are in meters not feet.

Altimeter: Your elevation right now is 3035 m. The elevation at WP 3 is about 2560 m.
using an altimeter in the mountains
using an altimeter in zero visibility
Altimeter and Compass: Execute your descent in legs (orange dots); (1) to the saddle, (2) @ 18° to 2850 m, (3) 0° to 2700 m, (4) 13° to 2560 m.  when your altimeter indicates  between 2570 and 2550 m,  always give yourself a “window”,  you should be able to continue your descent, on a bearing of 56° (the orange arrow), right down to WP 5 and out of the clouds. 

Notes: The ridge down to WP 3 is wide but be sure you stay on it.  If you change your direction to 56° too early you’ll end up in a drainage to the right of “your” ridge (pink circle) which also bears about 56° and will lead to WP 5.  If you overshoot WP 3 you’ll end up in a drainage (pink arrow) which will eventually bear north. In either case you should be able to think your way through it.
2. Hiking Down a Canyon Using Altimeter, Distance, Time, and Pace:

You are descending Long Valley again from WP 3 to WP6. You’ve got your altimeter with you.  You want to exit the valley at the red arrow. 

Distance: Your measurement is2.1 km.

Pace: You’ve been moving at 11

Time: You’ll be there in about 23-25 min.

Altimeter: At WP 3 you are at el. 7800’.  Your exit point is at el. 7440’.

So: In 23 to 25 min and when your altimeter reads between 7450’ and 7430 m you’re on your way up to WP 6. 
using an altimeter in a canyon
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Map & Compass - Practical Applications of Using the Altimeter
An accurate altimeter is sometimes invaluable...