Helmet fire is a mental state characterized by unnaturally high stress and task-saturation and loss of situational awareness. The term originates in the military where pilots wear helmets to protect their head and to muffle noise.
Pilots most frequently get task-saturated when flying instrument approaches, especially in actual instrument meteorological conditions. A complex procedure must be followed while making radio calls, changing the speed and configuration of the aircraft, and maintaining assigned altitudes, all while flying by reference to instruments. When the sum of these tasks exceeds the pilot's capability to deal with them effectively, he becomes task saturated and unable to perform any one of the tasks proficiently. The pilot may lose situational awareness, become confused, disoriented, may stammer on the radio, may forget how to fly the approach or what the last clearance was. This can rapidly develop into an unsafe situation, in some cases leading to a mid-air collision or crash.