Glossary

This glossary contains information on terms, phrases and abbreviations used by the Aviation industry. While this list does not include all aviation terminology, it is the purpose of this glossary to aid the general viewer in better understanding aviation terms as it pertains to content on this website. A full list of aviation terminology can be found here.
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

R

Rapid decompression.

The almost instantaneous loss of cabin pressure in aircraft with a pressurized cockpit or cabin.

RB.

See relative bearing.

RBI.

See relative bearing indicator.

RCO.

See remote communications outlet.

Receiver autonomous integrity monitoring (RAIM).

A system used to verify the usability of the received GPS signals and warns the pilot of any malfunction in the navigation system. This system is required for IFR-certified GPS units.

Receiver-transmitter (RT).

A system that receives and transmits a signal and an indicator.

Region of reverse command.

Flight regime in which flight at a higher airspeed requires a lower power setting and a lower airspeed requires a higher power setting in order to maintain altitude.

Regions of command.

The “regions of normal and reversed command” refers to the relationship between speed and the power required to maintain or change that speed in flight.

REIL.

See runway end identifier lights.

Relative bearing (RB).

The angular difference between the aircraft heading and the direction to the station, measured clockwise from the nose of the aircraft.

Relative bearing indicator (RBI).

Also known as the fixed-card ADF, zero is always indicated at the top of the instrument and the needle indicates the relative bearing to the station.

Relative humidity.

The ratio of the existing amount of water vapor in the air at a given temperature to the maximum amount that could exist at that temperature; usually expressed in percent.

Relative wind.

Direction of the airflow produced by an object moving through the air. The relative wind for an airplane in flight flows in a direction parallel with and opposite to the direction of flight; therefore, the actual flight path of the airplane determines the direction of the relative wind.

Remote communications outlet (RCO).

An unmanned communications facility that is remotely controlled by air traffic personnel.

A specified level of accuracy defined by a lateral area of confined airspace in which an RNP-certified aircraft operates.