Glossary

Automated Surface Observing System (ASOS). Weather Axial flow compressor. A type of compressor used in a reporting system which provides surface observations every turbine engine in which the airflow through the compressor minute via digitized voice broadcasts and printed reports. is essentially linear. An axial-flow compressor is made up of several stages of alternate rotors and stators. The compressor Automated Weather Observing System (AWOS). ratio is determined by the decrease in area of the succeeding Automated weather reporting system consisting of various stages. sensors, a processor, a computer-generated voice subsystem, and a transmitter to broadcast weather data. Azimuth card. A card that may be set, gyroscopically controlled, or driven by a remote compass. Automatic dependent surveillance—broadcast (ADS–B). A function on an aircraft or vehicle that periodically B broadcasts its state vector (i.e., horizontal and vertical Back course (BC). The reciprocal of the localizer course position, horizontal and vertical velocity) and other for an ILS. When flying a back-course approach, an aircraft information. approaches the instrument runway from the end at which the localizer antennas are installed. Automatic direction finder (ADF). Electronic navigation equipment that operates in the low- and medium-frequency Balance tab. An auxiliary control mounted on a primary bands. Used in conjunction with the ground-based control surface, which automatically moves in the direction nondirectional beacon (NDB), the instrument displays the opposite the primary control to provide an aerodynamic number of degrees clockwise from the nose of the aircraft assist in the movement of the control. to the station being received. Baro-aiding. A method of augmenting the GPS integrity Automatic terminal information service (ATIS). The solution by using a nonsatellite input source. To ensure that continuous broadcast of recorded non-control information in baro-aiding is available, the current altimeter setting must selected terminal areas. Its purpose is to improve controller be entered as described in the operating manual. effectiveness and relieve frequency congestion by automating repetitive transmission of essential but routine information. Barometric scale. A scale on the dial of an altimeter to which the pilot sets the barometric pressure level from which the Autopilot. An automatic flight control system which keeps altitude shown by the pointers is measured. an aircraft in level flight or on a set course. Automatic pilots can be directed by the pilot, or they may be coupled to a radio Basic empty weight (GAMA). Basic empty weight navigation signal. includes the standard empty weight plus optional and special equipment that has been installed. Aviation medical examiner (AME). A physician with training in aviation medicine designated by the Civil BC. See back course. Aerospace Medical Institute (CAMI). Bernoulli’s Principle. A principle that explains how the Aviation Routine Weather Report (METAR). Observation pressure of a moving fluid varies with its speed of motion. of current surface weather reported in a standard international An increase in the speed of movement causes a decrease in format. the fluid’s pressure. AWOS. See Automated Weather Observing System. Biplanes. Airplanes with two sets of wings. Axes of an aircraft. Three imaginary lines that pass through Block altitude. A block of altitudes assigned by ATC to an aircraft’s center of gravity. The axes can be considered allow altitude deviations; for example, “Maintain block as imaginary axles around which the aircraft rotates. The altitude 9 to 11 thousand.” three axes pass through the center of gravity at 90° angles to each other. The axis from nose to tail is the longitudinal axis Bypass ratio. The ratio of the mass airflow in pounds per (pitch), the axis that passes from wingtip to wingtip is the second through the fan section of a turbofan engine to the lateral axis (roll), and the axis that passes vertically through mass airflow that passes through the gas generator portion the center of gravity is the vertical axis (yaw). of the engine. G-5