Acronyms

ACU
Analog Converter Unit
Aspen: Optional ACU provides compatibility between older, analog avionics and Aspen EFD systems. ACU units also outputs control parameters for the autopilot, suchs as desired heading and selected course.

ACU2
Analog Converter Unit 2
Aspen: Optional ACU2 provides same capability as ACU but adds ADF, Radio Altimeter and OAT inputs as well as heading synchro bootstrap (ARINC 407) and flight director capabilty. Using optional unlock card S-TEC 55X support is improved.

AD
Airworthiness Directive
Generic: Airworhiness Directives are issued by aviation authorities suchs as FAA and EASA. These include mandatory inspections or modifications.

ADAHRS
Air Data Attitude Heading Reference Systems
Generic: An ADAHRS consist of multiple electronic sensors to sense the attitude of the aircraft in roll, pitch and yaw as well as air data suchs as pitot and static pressure. These sensors are used to drive the basic T part of the primary flight display.

ADC
Air Data Converter
Air Data Computer
Generic: Air Data Converter measure pitot and static air pressure and convert these pressure values into electronic signals, which then can be used by other avionics for air speed and altimeter indicator, but also used in wind calculation etc.

ADF
Automatic Direction Finder
Generic: Radio navigation receiving systems which uses a loop and sense antenna, which can be combined into a single antenna, to find the direction towards and NDB beacon. The system has a relative low accuracy due and therefore is more and more abondoned.

ADI
Attitude Direction Indicator
Generic: Flight instrument which shows attitude as well as directional information in the form of a flight director. The attitude is show as an artificial horizon.

ADS-B
Automatic Dependent Surveillance – Broadcast
Generic: ADS-B is a supplementary system to transponders. It periodically broadcast data, such as GPS position. This gives ATC as well as other aircraft a much better resolution situational awareness then with regular radar systems.

ADS-R
Automatic Dependent Surveillance - Re-Broadcast
Generic: ADS-R is the re-broadcasting of received ADS-B data by a ground station. ADS-B data received on 1090MHz will be transmitted on the 978 MHz UAT frequency and vice versa. This technology is mainly used in the USA.

AFCS
Automatic Flight Control System
Generic: Auto pilot which can control either 1 upto 3 axis and might also include autotrim options.

AFM
Airplane Flight Manual
Generic: Airplane flight manual describes how to operate the system during normal and emergency operation. Modifications or optional equipment might have a seperate supplemental AFMS. On complex system there is often also a more extensive Pilot Guide.

AFMS
Airplane Flight Manual Supplement
Generic: Airplane flight manual supplement is a supplement of a system which was different to the orginal aircraft configuration. The aircraft could have have additional systems installed per STC or minor change. The supplement describes how to operate the system during normal and emergency operation. On complex system there is often also a more extensive Pilot Guide.

AGL
Above Ground Level
Generic: Height Above Ground Level is the height above the underlying ground surface.

AHRS
Attitude Heading Reference System
Generic: An AHRS consist of multiple electronic sensors to sense the attitude of the aircraft in roll, pitch and yaw. These sensors are used to drive the attitude indicator on the primary flight display.

ALI
Airworthiness Limitation Items
Generic: Airworthiness Limitation Items are mandatory safety critical maintenance and/or inspection requirements that are required to be performed at the listed intervals.

ALS
Airworthiness Limitation Section
Generic: Airworthiness Limitation Section is the section which contains airworthiness limitations for type certified products. In contains mandatory scheduled maintenance and/or inspection and/or replacement requirements which must be followed to keep in compliance with the type design.

ALT
Altitude
Generic: Altitude.

ALTC
Altitude Capture
Garmin: Autopilot modes, where an desired altitude is selected and the altitude capture is armed during climb or decent. The autopilot mode will switch from vertical speed mode to hold selected altitude.

AOA
Angle of Attack
Generic: Angle between chord and relative wind. AOA measurement are carried out to measure the lift reserve, which becomes more and more accepted in GA. AOA is often measured by rotating vanes, pressure differences or calculated using AHRS and ADC data.

AP
Auto Pilot
Generic: Automatic flight control system, available in one, two and three axes.

A&P
Airframe & Powerplant
FAA: Certified maintenance engineer under FAA regime.

APS4A
Altitude Preselect System
Avionik Straubing: Interface between Aspen EFD1000 and ARC 400B, 800B, 1000, Century 4, 41, 2000, Collins AP106, Bendix KFC200, KFC250, KFC300, S-Tec System 30, 50, 55, 55X, 60 or 65 autopilot systems. It adds altitude preselection and altitude hold functionality on the autopilot, controlled by the Aspen EFD1000 PFD.

ASI
Air Speed Indicator
Generic: Indicator which shows airspeed.

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