Duplex  A communication operation that uses the simultane-
ous operation of the transmit and receive equipment 
at two locations. 
DVM  Digital Voltmeter 
DX  Distance 
Dynamic  Dynamic Pressure is the dif ference between pitot and 
Pressure  static pressure. 
Dynamic  RAM constructed of capacitor elements. Memory 
RAM  cells must be periodically refreshed to keep capaci 
tors from discharging and losing data (see “Static 
RAM”). 
E 
EADI  Electronic Attitude Director Indicator 
EAI  Engine Anti-Ice 
EANPG  European Air Navigation Planning Group 
EAP  Engine Alert Processor 
EAROM  Electrically Alterable ROM 
EARTS  En route Automated Radar Tracking System 
EASIE  Enhanced ATM and Mode S Implementation in Europe 
EATCHIP  European ATC Harmonization and Integration 
Program 
EATMS  European Air Traffic Management System 
EC  Event Criterion 
ECAC  European Civil Aviation Conference 
ECAM  Electronic Caution Alert Module 
ECEF  Earth-Centered,Earth-Fixed 
Echo  The portion of the radiated energy reflected back to 
the antenna from the target (WXR). 
ECL  Emitter Coupler Logic 
ECMP  Electronic Component Management System 

ECP  EICAS Control Panel 
ECS  (1) Engineering Compiler System. An automated data 
storage system. 
(2) Environmental Control System 
(3) Event Criterion Subfield 
ECSL  Left Environmental Control System Card 
ECSMC  ECS Miscellaneous Card 
ECSR  Right Environmental Control System Card 
ED  EICAS Display 
EDA  Electronic Design Automation