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RADAR - On-board weather radar.

RADAR ALTIMETER - Device that senses aircraft`s height above the terrain. Different from normal (barometric) altimeter.

RADAR APPROACH CONTROL FACILITY (RAPCON) - A terminal ATC facility that uses radar and non radar capabilities to provide approach control services to aircraft arriving, departing, or transiting airspace controlled by the facility. This facility provides radar ATC services to aircraft operating in the vicinity of one or more civil and/or military airports in a terminal area. The facility may provide services of a ground controlled approach (GCA); i.e., ASR and PAR approaches. A radar approach control facility may be operated by FAA, USAF, US Army, USN, USMC, or jointly by FAA and a military service.

RADIO MAGNETIC INDICATOR (RMI) - An ADF-like display with a pair of pointers which might be attached to either VOR or ADF receivers.

RADIO NAVIGATION - Navigation relative to radio station, providing, for example, of relative bearing, range, lateral deviation, and glide slope; Examples include VOR, TACAN, and PLS. Radio navigation differs from other navigation in that the transmitter signals often dropout for a long period of time, like minutes. This can occur because of natural obstructions, or because the transmitter was shut down intentionally.

RADOME - A detachable nose cone made of plastic-type material, used to cover and protect an airplane`s radar antenna.

RAMJET - An aerodynamic duct in which fuel is burned to produce a high-velocity propulsive jet. It needs to be accelerated to high speed before it can become operative.

RATED MAXIMUM CONTINUOUS POWER - with respect to reciprocating, turbo propeller, and turbo shaft engines, means the approved brake horsepower that is developed statically or in flight, in standard atmosphere at a specified altitude, within the engine operating limitations established under Part 33, and approved for unrestricted periods of use.

RATED MAXIMUM CONTINUOUS THRUST - with respect to turbojet engine type certification, means the approved jet thrust that is developed statically or in flight, in standard atmosphere at a specified altitude, without fluid injection and without the burning of fuel in a separate combustion chamber, within the engine operating limitations established under Part 33 of this chapter, and approved for unrestricted periods of use.

RATED TAKEOFF AUGMENTED THRUST - with respect to turbojet engine type certification, means the approved jet thrust that is developed statically under standard sea level conditions, with fluid injection or with the burning of fuel in a separate combustion chamber, within the engine operating limitations established under Part 33 of this chapter, and limited in use to periods of not over 5 minutes for takeoff operation.

RATED TAKEOFF POWER - with respect to reciprocating, turbo propeller, and turbo shaft engine type certification, means the approved brake horsepower that is developed statically under standard sea level conditions, within the engine operating limitations established under Part 33, and limited in use to periods of not over 5 minutes for takeoff operation.

RATED TAKEOFF THRUST - with respect to turbojet engine type certification, means the approved jet thrust that is developed statically under standard sea level conditions, without fluid injection and without the burning of fuel in a separate combustion chamber, within the engine operating limitations established under Part 33 of this chapter, and limited in use to periods of not over 5 minutes for takeoff operation.

RATING - means a statement that, as a part of a certificate, sets forth special conditions, privileges, or limitations.

RAIL - runway alignment indicator light system.

REDLINE - For a given airplane, the airspeed above which it is unsafe to fly. Redlining the plane may over stress or even damage structural elements in the plane.

REIL - Runway End Identifier Lights.

REFERENCE LANDING SPEED - The speed of the airplane, in a specified landing configuration, at the point where it descends through the 50 foot height in the determination of the landing distance.

REPORTING POINT - A geographical location in relation to which the position of an aircraft is reported.

RESTRICTED AREA - Airspace designated under Part 73 within which the flight of aircraft, while not wholly prohibited, is subject to restriction.

RNAV - Area navigation device.

RNAV WAY POINT (W/P) - a predetermined geographical position used for route or instrument approach definition or progress reporting purposes that is defined relative to a VORTAC station position.

ROCKET - An aircraft propelled by ejected expanding gases generated in the engine from self-contained propellants and not dependent on the intake of outside substances. It includes any part which becomes separated during the operation.

ROLL AXES - One of the three axes of flight which specifies the action around a central point.

ROTOCRAFT - A heavier-than-air that depends principally for its support in flight by the lift generated by one or more of its rotors, including helicopters and gyroplanes.

RUDDER - The movable part of a vertical airfoil which controls the YAW of an aircraft.

RUNWAY INCURSION - Any occurrence at an airport involving an aircraft, vehicle, person, or object on the ground that creates a collision hazard or results in loss of separation with an aircraft taking off, intending to take off, landing or intending to land.