± . . . . . . . . . . . . . . . . . . . . Plus or Minus
°C . . . . Degrees Celsius (or Centigrade)
°F . . . . . . . . . . . . . . Degrees Fahrenheit
A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Air
A/C . . . . . . . . . . . . . . . . . . . . . . . Aircraft
A/D . . . . . . . . . . . . . . . . Analog-to-Digital
A/FD . . . . . . . . Autopilot / Flight Director
A/P . . . . . . . . . . . . . . . . . . . . . . Autopilot
A/T. . . . . . . . . . . . . . . . . . . . . Autothrottle
A429 . . . . . . . . . . ARINC 429 digital data
communication standard
AAC. . . . . . . . . . . Auxiliary AC Contactor
AAC. . . . . . . . Aeronautical Administrative
Communications
AAL . . . . . . . . . . . . . .Above Airport Level
AC . . Advisory Circular - FAA publication
AC . . . . . . . . . . . . . . . Alternating Current
ACARS . . . . . . . Aircraft Communications Addressing and Reporting System