Glossary

Item	Description
ACARS	Aircraft Communications Addressing and Reporting System
ADS-B	Automatic Dependant Surveillance - Broadcast
ADS-C	Automatic Dependant Surveillance - Contract
ANSP	Air Navigation Service Provider
ATC	Air Traffic Control
ATCO	Air Traffic Control Officer
ATD	Along-track Distance
ATM	Air Traffic Management
CI	Cost Index
DME	Distance Measuring Equipment
Feet	A unit used to measure pressure altitude. One foot is 0.3048m
Flight level	An altitude measured in hundreds of Feet
FIR	Flight Information Region
FMS	Flight Management System
Great circle	The shortest path between two points over a sphere
Geodesic	The shortest path between two points over an ellipsoid
GNSS	Global Navigation Satellite System
GPS	Global Positioning System
ICAO	International Civil Aviation Organization
ISA	International Standard Atmosphere
LADR	Location of an Aircraft in Distress Repository
Leg	The path between a pair of waypoints
LORAN	LOng RAnge Navigation a radio navigation system
MASPS	Minimum Aviation System Performance Standards
MOPS	Minimum Operational Performance Standards
NAVAIDs	Navigation Aids
Navstar	The original Global Positioning System (GPS)
OBPMA	On-board performance monitoring and alerting
OFP	Operational Flight Plan
PBN	Performance-based Navigation
PDE	Path Definition Error
RNP	Required Navigation Performance
Route	A sequence of waypoints
SIMD	Single Instruction, Multiple Data
VORTAC	Visual Omni-Range Tactical Air Navigation
WGS-84	World Geodetic System – 1984
XTD	Across-track Distance