The most crucial aspect of an orienteering course is that every control is exactly where it is meant to be. An incorrectly placed control will almost inevitably mean the cancellation of any course that uses that particular control.
One of the main tasks of the controller is to ensure that controls are correctly and fairly placed for an event.
There are a couple of basic "rules" that govern the placement of controls in general:
On easy navigation courses, there needs to be a control at every major change of direction. The controls need to be placed on the approach side of the feature so they can be easily seen by the beginning orienteer. When a control is placed at a track junction, then the control needs to be placed just into the beginning of the road or track that the competitor will be taking for their next leg. In other words, once the competitor is at the control, they are facing in the right direction to move off on the next leg.
For moderate and hard navigation courses, the competitor is meant to see the feature before seeing the control (providing the feature stands higher than the control stand and flag, which is not always the case). This means that the flag is generally on the opposite side of the feature from which the competitor is approaching.
Several points need to be remembered when actually placing the control:
The control must be where it is meant to be. This should not be a problem when the control site feature is a point feature (eg. a boulder, root mound, knoll, rock-face, etc.). However, there is the possibility of error when the feature is a contour feature or a linear feature. The likelihood of error with a linear feature is avoided by placing the control at a bend or corner (of a fence, track, watercourse). With a contour feature such as a gully or spur, then it is more difficult to determine exactly where the control should be placed. For example, how far up or down the gully should it be? Control descriptions allow for the planner to identify the site as in the upper part or lower part of a gully, but this is only really useful in a reasonably short gully (such as is common in the Pittwater sand dunes). In a longer gully, then the planner needs to locate the control where there is a good reference point such as a near-by point feature. It is likely that this feature will also be used by competitors as an attack point. If there is no reasonable point from which to locate the control, then there is the risk that this becomes a "bingo".
An important task of the controller is to make sure that the chosen control sites are accurately represented on the map. If for some reason they don’t quite match up eg. there might be an unmapped feature, or the relationship between the mapped features mightn’t look quite right, then the controller should possibly suggest to the planner that that control should possibly be moved to a nearby feature that they feel is better represented. Remember, mappers are human and given the large areas covered by our maps, there will be small errors or ‘misfits’.
The control must not be hidden. Once the competitor reaches the correct side of the control feature, the control should be clearly visible. After all, the challenge of orienteering is how to navigate to the feature, not a treasure hunt for the control once you are there. It is very easy for the planner and controller who might have visited a control site several times and become familiar with the terrain to feel that the control is too obvious, and want to tuck it away a bit. The role of the controller is to ensure that the control is fairly placed. It should not be tucked in tight against a rock. (How many of us at some stage have stood on a rock or rock-ledge and not seen the control just below our feet because it is tucked in tight?) A good guide here is that you should be able to comfortably move between the control stand and the feature.
A control can also be hidden by vegetation such as bracken or a fallen tree or a tree trunk, and this is not obvious to the planner and controller until they actually put the control I place. With low vegetation then you can generally trample it down a bit to improve visibility. If there is a fallen tree or tree trunk blocking the competitor’s view of the control, then it is best to ‘ease’ the control away from the obstruction to make it more visible.
If planners and controllers remember that our sport is meant to be enjoyable and fair, no one will complain if any control site is possibly a little easier to locate that is generally expected. Hidden and bingo controls are unfair, and no-one enjoys a frustrating treasure hunt.