There are few things worse than that feeling in the pit of your stomach when you realise that the ridgeline you were expecting to appear on your right after 1km has failed to show up, and there is a spot height on your left where a creek junction should be. You realise you are geographically challenged. Time for the OODA loop to kick in. Sit down, have a cup of tea. I have rather bemusedly watched other folks reactions in this situation which verge on panic. They may try to fit the map into the new reality that faces them, they may try to backtrack on some random bearing, or just simply race around full stop. Other times I have been somewhat less than bemused when the person making important decisions is panicking, possibly affected by stress and dehydration, and blustering when it's obvious they have no idea.
So, why the cup of tea? Well, you can't get more lost by staying still, so you may as well sit, relax, and work out what happened. First things first, you have all the tools to relocate your position from the Navigation section. So it's not so bad. Also, if you are separated from a larger group, you have the ability to shout or blow the whistle you should have convenient. It's better to look a bit sheepish to find you were only 50m geographically challenged, rather than stay quiet and let everyone else walk on without you. It is amazing the number of people who get separated from a group on a simple trail hike, then get 'lost' for a few days. If they had just made a bit of noise, the group could have reorganised. Similarly, it is amazing the number of people who wander away from the carpark and find themselves lost after blindly wandering around 'looking' without some sort of plan.
Second things second - if you are lost as part of a team, use them. Get each individual to do their own static relocation methods independently, then compare notes. Don't bully others, or be bullied by others. The best navigator in the team may be the meekest one. In the army at Section/squad level I always had my 2IC as check navigator. So at platoon level, there are 4 primary navigators and 4 CheckNavs. As an amusing (maybe) anecdote, I was on a jungle exercise where the three sections had been patrolling independently and we had RV'd to a night location where the Platoon Commander was supposed to have marched into to meet us. We all appeared, married up (got together without shooting each other), then the Platoon Commander came over the radio asking where we were. Well, 3 commanders plus 2IC's had from different areas independently navigated to the same location, but it was still hard convincing the officer he was in the wrong place. Officers. Humph... I digress
During your Route Planning you will have prepared your Navigation Data sheet with the legs, bearing, distances and notes. During the course of your travel you will have marked off on your map your leg points and RV points. If you didn't, you may be kicking yourself now. Mentally backtrack from your start point for the day. Which RV's were you definitely sure you went through? Were there any you were a bit uneasy about, maybe something didn't quite feel right, but it seemed close enough to not worry about the possibility you were mistaken. What distance have you travelled from your last sure-as-sure position? Draw a circle with the radius of the distance travelled since centered on that sure-as-sure point, and you now have the worst possible scenario. That's not so bad, is it? Feeling of panic subsiding - we have ascertained we are indeed somewhere on the map!
Now we have the worst possible scenario, let's narrow it down. Use your map and notes to mentally retrace your planned route, and look for what could have gone wrong. One of the most common errors occurs in terrain where there are similarly shaped parallel features such as ridges or creek lines. It is very easy to start off down the wrong spur from a spot height, particularly in mountains. Subtle changes in direction may be undetected for a while until your next control point fails to appear when expected. This could be the cause. Did you have route legs that involved contouring? If you are not paying close attention to your bearing relative to distant features, it is possible to track either too far, or not far enough around the contour. Did your route require following creek lines? These can change since the map was made. Mentally retracing your route will narrow down an arc of potential error, within which you should be.
Your continual practice at doing Resections should now help calm your nerves. You know where you are within the ballpark from your static backtrack. Go through the Resection process - distant features first, closer features to narrow down the triangle of uncertainty, then pinpoint your position with the reality check of the microtopography around you. Make predictions about what features you should see, at what distance, and in which direction to test whether you are correct.
It may be necessary to move to try to relocate your position. You may need to move to a higher point to ensure you are on the type of feature you think your are. For example, you might be on a false crest and not realise it. You may need to get higher to get a better view for a good resection. In close country a resection may not be possible, and you might need to try to map out the country in your immediate vicinity and try and align it with the arc on your map. DO NOT LEAVE YOUR PACK BEHIND AS A MARKER!
A basic search pattern could consist of simply pacing out a distance, say 50m, from your current position on each of the cardinal points; drawing a map as you go. This would give you a coarse map of 100x100m2. This map-on-the-move is important. If worst comes to worst, and you end up having to traverse larger distances to try and relocate your position, your map will begin to more closely resemble the terrain within which you are geographically challenged.
Personally, in more open and mountainous country I prefer to venture 100m from the radius - while still staying in visual range. Particularly in mountainous areas, some features that appear obvious from the map may be hidden from your view. Moving a few 100m may get that pesky mountain of of the way so you can see the big one hiding behind it. Always look at the relative elevation of features. This is a problem of intervisibility - you may not be able to see over a small feature blocking a bigger one.
It is an adage that when 'lost', the compass and map are generally right. YOU are probably wrong. However, sometimes things could happen. Check your compass against other team members compasses, and your backup. Sometimes they can get bashed a bit too hard and damaged. I have mentioned ferrous objects like rifles. High tension electric lines can cause deflections. High quantities of iron in the earth can cause local problems. However these are unlikely to propagate over a huge distance. If you are using a coarse scale map and have been navigating map-to-ground, it may be that you have been misinterpreting the map. Not really an equipment error. If you have satellite navigation of some sort check it is receiving enough satellites, that the estimated error is not totally outrageous, that is is set to the correct map datum, that the batteries are OK. Using the reported position, use the procedure outlined in the Static backtrack section to draw a circle around the Satnav Position with the radius of the circle being the expected error. Do a map study of this area to see if it agrees with the terrain around you. Hey, some government may have shut down the system for a wee while as a test. It happens (rarely). If you unexpectedly and inadvertently hitched a ride on an Intercontinental Ballistic Missile, your Satnav may not work due to some silly American military restriction. But you probably would have noticed that by that stage.
For whatever reason, none of this has worked and you are really not sure where you are. Onto Plan B. Revisit the OODA loop. What options are available? If you have filed some sort of hiking plan, then if you are overdue hopefully the cavalry will arrive. In which case it is probably best to set up camp, and make sure the rest of your other survival needs are taken care of. Now is the time to plan for Rescue