Boston West Fair Skies

​​Keep our skies fair

Glossary of Terms 

ATC – Air Traffic Control: these are the FAA personnel in the tower and other facilities that control the safe movement of aircraft in our skies. ATC is solely responsible for flights once they leave the runway.

BLANS – Boston Logan Airport Noise Study, for more information go to the Massport website:  http://www.bostonoverflightnoisestudy.com/index.aspx

CATEX – CATegorical EXclusions, refers to a category of actions that the FAA can use to establish or change procedures if they do not individually or cumulatively have a significant effect on the environment. A CATEX is not an exemption or waiver of NEPA review; it is however a greatly reduced level of NEPA review. As part of the FAA’s 2012 reauthorization – implementation of PBN and RNAV can be done under CATEX.

DNL – Day Night (average-sound) Level, the noise measuring metric system used by the FAA. DNL is the average noise in a 24-hour period. The noise between 10 p.m. and 7 a.m. has a 10 dB (decibels) “penalty” to reflect the community background noise decrease during that period. The DNL threshold used by the FAA is 65 DNL, which is extremely high. A reduction to 55 DNL would not be relevant for GPS guided planes following the narrow and precise RNAV routes. DNL does not take into consideration the engine noise impact on human ears. It was an appropriate system for radar navigation. It is an obsolete metric when used in conjunction with GPS navigation which sends planes over the same neighborhoods, every two minutes or less for long periods of time. RNAV requires a metric that considers dwell and persistency over the same targeted homes.

EA – Environmental Assessment, a 255 page report on the study done and FONSI prior to 33L RNAV SID implementation. The entire report can be found here:


EDR – Environmental Data Report, a report produced by Massport. The 2014 report is 447 pages long and can be found by here: https://www.massport.com/media/342451/2014_EDR_Web_Version_file1.pdf

Fair Skies – various coalitions have been formed at state and national level using the “Fair Skies” name; Fair Skies is now associated with citizens grassroots organizations fighting for a more fair noise distribution.

FONSI – Findings Of No Significant Impact. As part of NEPA - a FONSI is issued when environmental analysis and interagency review during the EA process find a project to have no significant impacts on the quality of the environment.

Logan CAC – Logan Community Advisory Committee represents those communities which have authorized representatives and which are, or may be affected by Airport-related aircraft noise, http://www.bostonoverflight.com/study_participants.aspx#CAC. It was formed as part of the BLANS process, it in Phase 3 and will be dissolved once this phase is completed (projected to be in 2016).

Massport – The Massachusetts Port Authority. The State Agency responsible for the operation of Logan Airport, Hanscom Field, Worcester Regional Airport as well as the Port of Boston.

Massport CAC  - a new CAC established in 2013 by the State Legislature to supersede the Logan CAC and which will include also Hanscom, Worcester and the Port Authority. The Massport CAC has 40 communities that can appoint representatives.

NAS – National Airspace System

NEPA - National Environmental Policy Act of 1969 (NEPA) was signed into Law in 1970. NEPA established a national environmental policy intentionally focused on Federal activities and the desire for a sustainable environment balanced with other essential needs of present and future generations of Americans.

NextGen - is an umbrella term for the ongoing, wide-ranging transformation of the United States' national airspace system (NAS). At its most basic level, NextGen represents an evolution from a ground-based system of air traffic control to a satellite-based system of air traffic management. Nov 3, 2009 https://www.faa.gov/nextgen/

Congressional Quiet Skies Caucus – a coalition formed in 2014 by Congresspeople in Washington D.C. Massachusetts is represented by Congresswoman Katherine Clark and Congressman Michael Capuano (who also serves on the House Committee on Transportation and Infrastructure and Aviation Subcommittee).

RNAV - or Area Navigation is a form of Performance Based Navigation (PBN) that makes use of satellite/GPS routing and waypoints and replaces conventional ground radar and ATC. 

Runway 33L – One of six runways at Boston’s Logan Airport (BOS). It is used in conjunction with runways 32 and 27 is the airport’s North-West configuration (http://bit.ly/LoganRunwayOperations).  In the winter months (Oct-March), when the winds frequently come from the NW, runway 33L can be used for as many as 3,000 departures per month. In the summer months, this goes down to 1000-1500 (detailed data available here: http://bit.ly/LoganRunwayUse). Over the course of 2014, 17% of the planes departing Logan used Runway 33L.  Runway 33L was extended to meet safety standards which meant that it was closed for most of the summer in 2011 and 2012 resulting in a lower % of use in those years.

Since 33L RNAV was implemented in June of 2013, departing flights travel to a waypoint (TEKKK) in Medford and then follow one of four narrow GPS-guided paths to their destinations.  The FAA has nicknamed RNAV flight paths “Highways in the Sky”.  In the case of 33 L RNAV one path continues northwest over Somerville and then Winchester – the other three paths head southwest and traverse Somerville, Arlington, parts of N.Cambridge continuing over Belmont and then Watertown.  These are the communities united under the Boston West Fair Skies coalition fighting a more fair distribution of noise generated by the changes that have been implemented as part of 33L RNAV.

SID – Standard Instrument Departure

SOP – Standard Operating Procedure