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Radial Error Probability: A probability that a percentage of one-dimension measurements will lie on a radial (line) of given length, with the origin centered at truth or mean of the measurements; used to specify test cases for measurement errors of sensors of one dimension, such as vertical velocity.

Radio Navigation: Navigation relative to radio station, providing, for example, of relative bearing, range, lateral deviation, and glideslope. 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. In hostile territory, a PLS can locate a downed pilot, who would be foolhardy to be continuously transmitting, but would transmit infrequently with small bursts of data. The Radio- Navigation system accommodates this phenomenon by simulating range and bearing to the fixed site when it is not transmitting. After reacquiring a mobile transmitter, the mobile station's position is re-determined. The navigation component supports wash-out filters on output data. 

Real time: Time in a computational process which runs at the same rate as a physical process.

Reasonable Care: The standard of care in negligence cases; the duty to act reasonably so as to avoid harming others.

Reasonableness: A test to determine if data is reasonable, for example, radar altitude must be positive and two devices should return similar data within known limits of each other.

Remand: The decision of an appellate court to send a case back to the trial court with instructions on how to correctly decide the case; often used with the term “reversed.” Reversed means that the appellate court overturned the trial court’s decision.

Remedies: Relief that the plaintiff receives from the defendant in a lawsuit. Often this will include monetary damages or equitable relief (i.e. injunctions).

Respondent: The party that won at trail.

Rudder: A control surface on fixed-wing aircraft, usually mounted at aft end of the fuselage sticking up (like a dorsal fin), that controls yaw (heading), and is controlled by the pedals.