Aiming off is a cross-country navigation technique for finding a destination like a shelter or a landmark that is located along a natural or man-made landscape feature (also called a linear feature) like a stream, a ridge, or a path. Instead of setting a bearing directly for your target destination, the idea is to follow a bearing that is deliberately set to the right or left of it, so you know which way to turn when you reach the linear feature.
This is a particularly useful technique in bad weather such as mist or rain when you can’t see your destination, when your view of the destination is blocked by tree cover, or the contour of the land is relatively flat and you can’t use slope angle to determine which way to turn when you reach the linear feature.
Most off-trail hikers also experience a 0-4 degree drift when following a compass bearing that makes it unlikely that you’ll hit a point on the map dead-on instead of walking past it to the side. Aiming off helps negate the impact of this variability and puts you at a known location close to your target
To illustrate, let’s say we’re standing on top of a peak named Ragged Jacket and we want to hike off-trail to the Blue Brook Shelter*. If we set a direct course to the shelter, we’d be walking along the 330 degree true bearing on the left, above. If we miss the shelter by walking past it on either side and reach the trail it’s on (dashed line), we don’t know whether to turn left or right to get to it.
If instead we aim off, and follow the right-hand 350 degree true bearing shown above, we’ll intersect the trail that the shelter is on to its right, and from there we know then to turn left to reach the Blue Brook Shelter.
* This is an old map and should not be used for navigation purposes. The Blue Brook Shelter shown here has been dismantled and moved to another location in the White Mountain National Forest.