Although capable of impressive performance, the light weight and low power of these craft make them suitable only for indoor use. This is not necessarily a serious limitation, as a skilled pilot can have hours of enjoyment zooming through the house at terrifying speed, strafing the sofa, and practicing hot LZ drops on the coffee table. But acquiring that skill requires considerable practice.
One problem, common to all radio controlled models, is the control reversal which occurs when the orientation of the model is different from the orientation of the pilot. If a model which is facing the pilot is drifting to the left into the wall, the natural reaction (push the stick to the right) will quickly convert a potential crash into an actual crash. This will usually damage the model, often damage furniture, and occasionally damage the pilot. Damage to the furniture and pilot is unfortunate, but damage to the helicopter usually takes the form of broken blades or a bent rotor shaft, which must be replaced before flying can resume. Replacement parts are readily available, but the cost quickly adds up, and time spent repairing the craft is time taken away from practice.
If the helicopter knew where the walls (and the ceiling, and the sofa, etc.) were, it could simply refuse to get within a certain distance of them, giving the fledgling pilot time to realize his error and correct it. This is clearly an application for our localization system, but it is an especially challenging one: