Abbreviations and Acronyms
AC or A/C – Aircraft
AFTPro – Advanced Flight Track Procedures
AGL – Above Ground Level
AIP – Airport Improvement Program
ANMS – Airport Noise Monitoring System
ARFF – Airport Rescue and Fire Fighting Facility
ARTCC – Air Route Traffic Control Center
ATC – Air Traffic Control
ATCT – Airport Traffic Control Tower
CDA – Chicago Department of Aviation
dB – Decibel
DNL or LDN – Day-Night Average Sound Level
DOA – Department of Aviation
FAA – Federal Aviation Administration
FAF – Final Approach Fix
FAR – Federal Aviation Regulation
FOD – Foreign Object Debris
ft. – Feet
FPM – Feet per Minute
GIS – Geographic Information System
GPS – Global Positioning System
GRE – Ground Run-Up Enclosure
IFR – Instrument Flight Rules
ILS – Instrument Landing System
IMC – Instrument Meteorological Conditions
INM – Integrated Noise Model
KIAS – Knots Indicated Airspeed
MDW – Chicago Midway International Airport
MSL – Mean Sea Level
NAVAIDS – Navigational Aids
NOTAM – Notice to Airmen
OM – Outer Marker
ORD – Chicago O'Hare International Airport
PFC – Passenger Facility Charge
Part 150 – FAR Part 150 Noise Compatibility Program
RMT – Remote Monitoring Terminal
RNAV – Area Navigation
SEL – Sound Exposure Level
SID – Standard Instrument Departure Procedure
STARS – Standard Terminal Arrival Routes
TRACON – Terminal Radar Approach Control
VFR – Visual Flight Rules
VMC – Visual Meteorological Conditions
VOR – Very High Frequency (VHF) Onmidirectional Range
VORTAC – VHF Onmidirectional Range with Tactical Air Navigation
V2 -- Takeoff Safety Speed
Vs – Stalling Speed
Vfs – Final Segment Speed
Glossary of Terms
Day-Night Average Sound Level (DNL)
A noise measurement used to describe the average aircraft noise levels over a 24-hour period, typically an average day over the course of a year. DNL penalizes aircraft operations that occur between the hours of 10 p.m. and 7 a.m. an additional 10 decibels to account for increased sensitivity to nighttime noise. DNL may be determined for individual locations or expressed contours. DNL is currently the accepted measurement for aircraft noise analysis.
Decibel (dB)
A unit of relative loudness. The smallest amount of change that can be detected by the human ear is one decibel. A 20 decibel sound is 10 times as loud as a 10 decibel sound; a 30 decibel sound is 100 times as loud.
Federal Aviation Regulation (FAR) Part 150
FAR Part 150 was established by Congress under the Aviation Safety and Noise Abatement Act of 1979 for the purpose of developing a balanced and cost effective program to reduce the effects of aircraft noise on local communities.
Land Use Compatibility
The ability of land uses surrounding the airport to coexist with airport-related activities with minimum conflict.
NAVAID
Any facility used for guiding or controlling flight in the air or during the landing and takeoff of aircraft.
Noise Abatement
A procedure or technique used by aircraft at an airport to minimize the impact of noise on the communities surrounding an airport.
Run-Up
A routine procedure for testing an aircraft engine at a high power setting. Engine run-ups are normally conducted by airline maintenance personnel checking an engine following maintenance.
Stage 2 Aircraft
Aircraft which meet the noise levels prescribed by FAR Part 36 and are less stringent than those established for the quieter "Stage 3" designation. The Airport Noise and Capacity Act required the phase-out of all Stage 2 aircraft by the end of 1999.
Stage 3 Aircraft
Aircraft that meet the most stringent noise levels set in FAR Part 36.