Active waypoint. The waypoint being used by the  FMS/RNAV as the reference navigation point for course  guidance. ADAHRS. See air data attitude and heading reference  system. ADC.  See air data computer. ADS-B.  See automatic dependent surveillance—broadcast. Advanced avionics information system. Any cockpit  electronic (avionics) system designed to provide information  or data to the pilot about aircraft status or position, planned  routing, surrounding terrain, traffic, weather, fuel, etc.  Advanced avionics systems are generally evidenced by visual  displays of integrated information in lieu of mechanical or  stand alone instruments for one or two data sets each. AHRS.  See Attitude Heading Reference System. Air Data Attitude and Heading Reference System  (ADAHRS).  An integrated flight instrument system that  combines the functions of an air data computer (the “AD”  short for ADC) and an Attitude Heading Reference System  (AHRS) into one unit.  Air Data Computer (ADC).  The system that receives ram  air, static air, and temperature information from sensors, and  provides information such as altitude, indicated airspeed,  vertical speed, and wind direction and velocity to other  cockpit systems. Altitude alerting system.  The system that allows the pilot  to receive a visual and/or auditory alert when the airplane  approaches or deviates from a preselected altitude. Altitude capture. An autopilot function that enables  the autopilot to level the airplane at a selected altitude  automatically. Altitude function.  An autopilot function that maintains the  present altitude of the airplane. Annunciator panel.  Grouping of annunciator lights that is  usually accompanied with a test switch, which when pressed  illuminates all the lights to confirm they are in working order. Approach mode/function.  An autopilot function or mode  that allows the pilot to capture and track any VOR radial or  localizer with a higher degree of accuracy. Area navigation (RNAV). A method of navigation that  permits operations along any desired flightpath within the  area of coverage of station‑referenced navigation aids (e.g.,  GPS, VOR/DME, DME/DME, eLORAN), or within the  limits of a self‑contained navigation system (INS, doppler  radar), or any combination. Armed.  A system mode or function that is set to become  actively engaged at a later time, when certain conditions  are met. Attenuation.  See radar attenuation. Attitude Heading Reference System (AHRS). An  integrated flight instrument system that provides attitude,  heading, rate of turn, and slip/skid information. Automatic dependent surveillance—broadcast (ADS-B). A surveillance system in which an aircraft or vehicle to be  detected is fitted with cooperative equipment in the form of  a data link transmitter. The aircraft or vehicle periodically  broadcasts its GPS‑derived position and other information  (e.g., velocity) over the data link, which is received by  a ground-based transmitter/ receiver (transceiver) for  processing and display at an air traffic control facility. Automatic mode change.  Any change in mode or system  status initiated by the system, rather than by a deliberate  mode change action taken by the pilot. G-1 Glossary