Glossary

RF. Radio frequency. Runway edge lights. A component of the runway lighting system that is used to outline the edges of runways at night Rhodopsin. The photosensitive pigments that initiate the or during low visibility conditions. These lights are classified visual response in the rods of the eye. according to the intensity they are capable of producing. Rigging. The final adjustment and alignment of an aircraft Runway end identifier lights (REIL). A pair of synchronized and its flight control system that provides the proper flashing lights, located laterally on each side of the runway aerodynamic characteristics. threshold, providing rapid and positive identification of the approach end of a runway. Rigidity. The characteristic of a gyroscope that prevents its axis of rotation tilting as the Earth rotates. Runway visibility value (RVV). The visibility determined for a particular runway by a transmissometer. Rigidity in space. The principle that a wheel with a heavily Runway visual range (RVR). The instrumentally derived weighted rim spinning rapidly will remain in a fixed position horizontal distance a pilot should be able to see down the in the plane in which it is spinning. runway from the approach end, based on either the sighting of high-intensity runway lights, or the visual contrast of Rime ice. Rough, milky, opaque ice formed by the other objects. instantaneous freezing of small supercooled water droplets. RVR. See runway visual range. Risk. The future impact of a hazard that is not eliminated or controlled. RVV. See runway visibility value. Risk elements. There are four fundamental risk elements S in aviation: the pilot, the aircraft, the environment, and the SA. See selective availability. type of operation that comprise any given aviation situation. St. Elmo’s Fire. A corona discharge which lights up the Risk management. The part of the decision-making aircraft surface areas where maximum static discharge occurs. process which relies on situational awareness, problem recognition, and good judgment to reduce risks associated Satellite ephemeris data. Data broadcast by the GPS with each flight. satellite containing very accurate orbital data for that satellite, atmospheric propagation data, and satellite clock error data. RMI. See radio magnetic indicator. Sea breeze. A coastal breeze blowing from sea to land RNAV. See area navigation. caused by the temperature difference when the land surface is warmer than the sea surface. The sea breeze usually occurs RNP. See required navigation performance. during the day and alternates with the land breeze that blows in the opposite direction at night. RT. See receiver-transmitter. Sea level engine. A reciprocating aircraft engine having a Rudder. The movable primary control surface mounted on rated takeoff power that is producible only at sea level. the trailing edge of the vertical fin of an airplane. Movement of the rudder rotates the airplane about its vertical axis. Scan. The first fundamental skill of instrument flight, also known as “cross-check;” the continuous and logical Ruddervator. A pair of control surfaces on the tail of an observation of instruments for attitude and performance aircraft arranged in the form of a V. These surfaces, when information. moved together by the control wheel, serve as elevators, and when moved differentially by the rudder pedals, serve Sectional aeronautical charts. Designed for visual as a rudder. navigation of slow- or medium-speed aircraft. Topographic information on these charts features the portrayal of relief, Runway centerline lights. Runway lighting which consists and a judicious selection of visual check points for VFR of flush centerline lights spaced at 50-foot intervals beginning flight. Aeronautical information includes visual and radio 75 feet from the landing threshold. aids to navigation, airports, controlled airspace, restricted areas, obstructions and related data. G-26