Notice to Airmen. NOTAMs are created and transmitted by government agencies. A NOTAM is filed with an aviation authority to alert aircraft pilots of any hazards en route or at a specific location. The authority in turn provides a means of disseminating relevant NOTAMs to pilots. NOTAMs are issued (and reported) for a number of reasons, such as: hazards such as air-shows, parachute jumps, kite flying, rocket launches, etc.; flights by important people such as heads of state (sometimes referred to as Temporary Flight Restrictions, TFRs); closed runways; inoperable radio navigational aids; military exercises with resulting airspace restrictions; inoperable lights on tall obstructions; temporary erection of obstacles near airfields (e.g. cranes); passage of flocks of birds through airspace (a NOTAM in this category is known as a BIRDTAM); notifications of runway/taxiway/apron status with respect to snow, ice and standing water (a SNOWTAM); notification of an operationally significant change in volcanic ash or other dust contamination (an ASHTAM); and software code risk announcements with associated patches to reduce specific vulnerabilities.