Pilot deviations can occur in several different ways. Airborne deviations can result when pilots stray from an assigned, heading, altitude, or instrument procedure, or if they penetrate controlled or restricted airspace without ATC clearance. Ground deviations can happen while taxiing, taking off, or landing without clearance, deviating from an assigned taxi route, or failing to hold short of an assigned clearance limit. To avoid pilot deviations, follow these steps.