Glossary

Airspeed indicator. A differential pressure gauge that Alternate static source valve. A valve in the instrument static measures the dynamic pressure of the air through which the air system that supplies reference air pressure to the altimeter, aircraft is flying. Displays the craft’s airspeed, typically in airspeed indicator, and vertical speed indicator if the normal knots, to the pilot. static pickup should become clogged or iced over. Air traffic control radar beacon system (ATCRBS). Altimeter. A flight instrument that indicates altitude by Sometimes called secondary surveillance radar (SSR), which sensing pressure changes. utilizes a transponder in the aircraft. The ground equipment is an interrogating unit, in which the beacon antenna is mounted Altimeter setting. Station pressure (the barometric pressure so it rotates with the surveillance antenna. The interrogating at the location the reading is taken) which has been corrected unit transmits a coded pulse sequence that actuates the aircraft for the height of the station above sea level. transponder. The transponder answers the coded sequence by transmitting a preselected coded sequence back to the Altitude engine. A reciprocating aircraft engine having a ground equipment, providing a strong return signal and rated takeoff power that is producible from sea level to an positive aircraft identification, as well as other special data. established higher altitude. Airway. An airway is based on a centerline that extends from Ambient pressure. The pressure in the area immediately one navigation aid or intersection to another navigation aid surrounding the aircraft. (or through several navigation aids or intersections); used to establish a known route for en route procedures between Ambient temperature. The temperature in the area terminal areas. immediately surrounding the aircraft. Airworthiness Certificate. A certificate issued by the FAA AME. See aviation medical examiner. to all aircraft that have been proven to meet the minimum standards set down by the Code of Federal Regulations. Amendment status. The circulation date and revision number of an instrument approach procedure, printed above Airworthiness Directive. A regulatory notice sent out by the procedure identification. the FAA to the registered owner of an aircraft informing the owner of a condition that prevents the aircraft from Ammeter. An instrument installed in series with an electrical continuing to meet its conditions for airworthiness. load used to measure the amount of current flowing through Airworthiness Directives (AD notes) are to be complied with the load. within the required time limit, and the fact of compliance, the date of compliance, and the method of compliance are Aneroid. The sensitive component in an altimeter or recorded in the aircraft’s maintenance records. barometer that measures the absolute pressure of the air. It is a sealed, flat capsule made of thin disks of corrugated Alert area. An area in which there is a high volume of pilot metal soldered together and evacuated by pumping all of training or an unusual type of aeronautical activity. the air out of it. Almanac data. Information the global positioning system Aneroid barometer. An instrument that measures the (GPS) receiver can obtain from one satellite which describes absolute pressure of the atmosphere by balancing the weight the approximate orbital positioning of all satellites in the of the air above it against the spring action of the aneroid. constellation. This information is necessary for the GPS receiver to know what satellites to look for in the sky at a Angle of attack. The angle of attack is the angle at which given time. relative wind meets an airfoil. It is the angle that is formed by the chord of the airfoil and the direction of the relative ALS. See approach lighting system. wind or between the chord line and the flight path. The angle of attack changes during a flight as the pilot changes Alternate airport. An airport designated in an IFR flight the direction of the aircraft and is related to the amount of plan, providing a suitable destination if a landing at the lift being produced. intended airport becomes inadvisable. G-3