A computer-driven weather data collection and reporting system that does not depend on human operation. Many small airports have ASOS or AWOS which report the current weather conditions at the airport using a synthesized voice over the radio.
A portion of ATC that manages the air traffic operating outside the boundaries of airport Towers and applicable Approach / Departure facilities. Officially called Air Route Traffic Control Center (ARTCC).
A radio facility which provides distance information from a particular station. DME transmitters are most often co-located with VORs which allows the pilot to determine the aircraft's distance from the VOR.
Company or business at an aiport that provides services and products to pilots such as fuel and oil, flight training, aircraft rental, hangaring, and maintenance, charts and maps, and other supplies.
A service available to VFR pilots from ATC on a load permitting basis where ATC will provide advisories regarding nearby air traffic and other information pertinent to the flight.
Facility that provides various services to pilots such as weather briefings and reports, filing of flight plans, search and rescue, and in some cases clearances from ATC.
A navigational system in which the reciever triangulates its position using syncronized signals from transmitters in a constellation of 24 satellites that orbit the earth. Unlike LORAN, can also provide altitude information along with position. Compare with LORAN
A procedure to 'hold' an aircraft from proceeding further along its route which involves the aircraft flying a 'racetrack' pattern around a particular point in space (at a specific location and altitude).
The set of regulations governing flights in limited visibility, 'bad weather' conditions. An IFR flight is always in contact with and under the control of ATC. Compare with VFR
A radio navigation system used for 'precision' approaches to an airport which offers both vertical (altitude), as well as horizontal (bearing) guidance to the pilot. Consists of two components: the localizer which provides the horizontal guidance, and the glide-slope which provides the vertical guidance. Compare with VOR
A unit of speed equal to one nautical mile per hour, written as 'knot' or 'knots.' Statute miles per hour is roughly equal to 1.15 times nautical miles per hour. (mph = 1.15 x knots)
Reference to height above sea level. Using this means of measuring altitude gives pilots, Flight Service and ATC a common height measurment without regard for the local height above the ground. See AGL
A measure of distance that is equal to 1/60 of a degree (one second) of latitude on the face of the earth. One nautical mile is equal to 6080 feet, or roughly 1.15 times that of a statute mile. (nautical mile = 1.15 x statute mile) See knot
An electronic navigational system in which the reciever triangulates its position using syncronized signals from geographically distant, low-frequency transmitters. Compare with GPS
Specifically designated airspace that is closed to civilian aircraft unless permission is granted by the controlling agency. Generally used by the military for high speed tests, training, and gunnery, among other purposes. Compare with MOA
A 'special' set of regulations that allow a VFR pilot to fly in reduced, but not limited, visibility conditions without resorting to an IFR flight plan. SVFR rules can only be used when a request is made to and approved by ATC. Also see IFR
A device that detects electrical activity in the atmosphere which is plotted on a screen showing direction and distance from the aircraft. Used to avoid areas of high electrical activity, which indicate the presence of thunderstorms at that location.
The local airport ATC facility that controls aircraft take-offs and landings, and the immediate runway environment. Depending on the amount of air traffic at a particular airport, there may also be Approach / Departure facilities.
A piece of radio equipment aboard an aircraft that replies with a preset code when interrogated by ATC equipment on the ground. Using the preset code, ATC's computers integrate their radar data with identification data reported by the transponder to give the controller more highly organized information on their radar screens, simplifying their work. The reply signal from a transponder is referred to as 'the squawk'.
The 'time-zone' at 0-degrees longitude that passes through England, and also called Greenwich Mean Time (GMT). UTC provides aviators a time reference that can be used with ATC the world over to describe departue times etc., without the confusion that would result by using the time in their local time zone. In aviation, UTC is also referred to as 'Zulu.'
A term used to describe instructions from ATC that are simply headings and altitudes to fly without reference to radio navigation stations. Used by controllers to direct air traffic onto final approach, avoid other aircraft, etc.
A navigation radio facility that transmits signals on each of the 360 degrees allowing the pilot to fly to or from the station on a specific heading. Also used for 'non-precision' approaches to airports, by providing horizontal (bearing) guidance. VORs often have DME co-located at the site. Compare with ILS
The set of regulations governing flights in 'good weather' conditions. A VFR flight, at the pilot's discretion, may or may not be in contact with ATC, nor is the flight under the control of ATC except when operating at high-traffic, towered airports. Compare with IFR
