DCE  Data Communications Equipment 
DCGF  Data Conversion Gateway Function 
DCMF  Data Communication Management Function 
DCMS  Data Communication Management System 
DCN  (1) Drawing Change Notice (2) Design Change Notice (3) Document Change Notice 
DCP  Display Control Panel 
DCPC  Direct Controller Pilot CommunicationDCS Double Channel Simplex. A communication system using two rf channels for non-simultaneous communi-cation. One channel is disabled while the other chan-nel is used to transmit. 
DCU  Data Concentration Unit 
DCV  Directional Control Valve 
DDA  Digital Differential Analyzer 
DDD  Dual Disk Drive 
DDM  Difference in Depth of Modulation 
DDP  Declarations of Design and Performance. A control document required by the United Kingdom Civil Aviation Authority (CAA) for certification of avionics equipment. 
DDS  Direct Digital Synthesizer 
DDT  Downlink Data Transfer 
DECCA  A navigation system widely used by shipping in Europe. The ground facilities consist of a master sta-tion and several slave stations. 
Decimal  Base-10 counting system. Numbers include 0,1,2,3, 4,5,6,7,8,9. 
ded  Dedicated 
DEFDARS  Digital Expandable Flight Data Acquisition And Recording System 
DEFL  Deflection 

DEG Degree
Demand AN ACARS mode of operation in which communica Mode tions may be initiated by the ground processor or the airborne system.
D e s e n s i t i z a t i o n TCAS sensitivity level (threat volume) reduction
DEST  Destination 
DEV  Deviation 
DFA  Direction Finding Antenna 
DFCS  Digital Flight Control System 
DFDAF  Digital Flight Data Acquisition Function 
DFDAU  Digital Flight Data Acquisition Unit. The DFDAU sam-
ples,conditions and digitizes the flight data. 
DFDR  Digital Flight Data Recorder 
DFDU  Digital Flight Data Unit 
DFIDU  Dual Function Interactive Display Unit