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Pilot/Controller Glossary 

10/5/23 

When equipment, capabilities, and controller workload permit, certain advisory/assistance services may be 

provided to VFR aircraft. 

(See AIR ROUTE TRAFFIC CONTROL CENTER.) 
(Refer to AIM.) 

EN ROUTE AUTOMATION SYSTEM (EAS)

 The complex integrated environment consisting of situation 

display systems, surveillance systems and flight data processing, remote devices, decision support tools, and 

the related communications equipment that form the heart of the automated IFR air traffic control system. It 

interfaces with automated terminal systems and is used in the control of en route IFR aircraft. 

(Refer to AIM.) 

EN ROUTE CHARTS

 

(See AERONAUTICAL CHART.) 

EN ROUTE DECISION SUPPORT TOOL (EDST)

 An automated tool provided at each Radar Associate 

position in selected En Route facilities. This tool utilizes flight and radar data to determine present and future 

trajectories for all active and proposal aircraft and provides enhanced automated flight data management. 
EN ROUTE DESCENT

 Descent from the en route cruising altitude which takes place along the route of flight. 

EN ROUTE HIGH ALTITUDE CHARTS

 

(See AERONAUTICAL CHART.) 

EN ROUTE LOW ALTITUDE CHARTS

 

(See AERONAUTICAL CHART.) 

EN ROUTE MINIMUM SAFE ALTITUDE WARNING (E

MSAW)

 A function of the EAS that aids the 

controller by providing an alert when a tracked aircraft is below or predicted by the computer to go below a 

predetermined minimum IFR altitude (MIA). 
EN ROUTE TRANSITION

 

(See SEGMENTS OF A SID/STAR.) 

EN ROUTE TRANSITION WAYPOINT 

(See SEGMENTS OF A SID/STAR.) 

eSRS

– 

(See ENHANCED SPECIAL REPORTING SERVICE.) 

EST

 

(See ESTIMATED.) 

ESTABLISHED

 To be stable or fixed at an altitude or on a course, route, route segment, heading, instrument 

approach or departure procedure, etc. 
ESTABLISHED ON RNP (EoR) CONCEPT– A system of authorized instrument approaches, ATC procedures, 

surveillance, and communication requirements that allow aircraft operations to be safely conducted with 

approved reduced separation criteria once aircraft are established on a PBN segment of a published instrument 

flight procedure. 
ESTIMATED (EST)

When used in NOTAMs “EST” is a contraction that is used by the issuing authority only 

when the condition is expected to return to service prior to the expiration time. Using “EST” lets the user know 

that this NOTAM has the possibility of returning to service earlier than the expiration time. Any NOTAM which 

includes an “EST” will be auto

expired at the designated expiration time. 

ESTIMATED ELAPSED TIME [ICAO]

 The estimated time required to proceed from one significant point to 

another. 

(See ICAO Term TOTAL ESTIMATED ELAPSED TIME.) 

ESTIMATED OFF-BLOCK TIME [ICAO]

 The estimated time at which the aircraft will commence movement 

associated with departure. 

PCG E