The Official Website of The Massachusetts Department of Transportation - Aeronautics Division

Airspace Review Process

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Review Process Overview

Submitting a Request

According to Massachusetts Law, the farthest possible distance away from an airport that an object can be considered an obstruction, if tall enough, is 2 miles. Therefore, if the construction or alteration is being completed within two miles of a public-use airport in MA a request for airspace review must be submitted.

  • You can submit a request for Airspace Review electronically by going to:
  • Make sure you have the following information available when filling out the application:
    • Sponsor and sponsor’s representative information including name, company name, address, phone number, and e-mail address
    • A detailed project description including the FAA Obstruction Evaluation Number if you have one
    • Name of the Nearest Airport and location of the city of the proposed construction
    • Latitude and Longitude coordinates in NAD 83 or NAD 27 of the proposed construction
    • The site elevation above mean sea level (MSL), the maximum height of proposed construction above ground level (AGL), and the maximum elevation of the proposed construction above MSL — these elevations are required to be in feet

Requestors should allow 30 days for the study to be completed, however on average it takes approximately 2 weeks for a determination to be made.


Airspace Reviews, or Obstruction Evaluations, are performed by the MassDOT Aeronautics Division and the Federal Aviation Administration (FAA), respectively, to determine if a type of construction or alteration of a structure in the vicinity of an airport will penetrate an imaginary surface and become an obstruction.

Imaginary Surfaces are three dimensional surfaces surrounding a runway and airport that determine safe altitudes for aircraft approaching or departing an airport. The Commonwealth of Massachusetts defines imaginary surfaces based on Massachusetts General Law Chapter 90 Section 35B and the Code of Massachusetts Regulations (702 CMR). The FAA defines its imaginary surfaces based on Title 14 Code of Federal Regulations (14 CFR part 77).

Obstructions: An obstruction is any object, natural or man-made, that penetrates above the imaginary surface and may interfere with a pilots ability to safely fly an aircraft. Obstructions may be temporary or permanent and some examples include:

  • Crane
  • Wind Turbine
  • Building
  • Light/Flag/Utility Poles
  • Solar Panels

Public-Use Airport: According to 14 CFR part 77 a public-use airport is “available for use by the general public without a requirement for prior approval of the airport owner or operator.” List of Massachusetts public-use airports

FAA Obstruction Evaluation Program

According to the FAA Website any construction/ alteration that meets the following conditions must submit for an obstruction evaluation:

  • Any construction or alteration exceeding 200 ft AGL
  • Any construction or alteration:
    • Within 20,000 ft of a public-use or military airport which exceeds a 100:1 surface from any point on the runway of each airport with its longest runway more than 3,200 ft.
    • Within 10,000 ft of a public use or military airport which exceeds a 50:1 surface from any point on the runway of each airport with its longest runway no more than 3,200 ft.
    • Within 5,000 ft of a public-use heliport which exceeds a 25:1 surface
  • Any highway, railroad or other traverse way whose prescribed adjusted height would exceed the above noted standards
  • When requested by the FAA
  • Any construction or alteration located on a public use airport or heliport regardless of height or location

To submit a request for an obstruction evaluation go to: to e-file. The information required is similar to that needed for a MassDOT Airspace Review.


No Hazard to Air Navigation

If the proposed construction/alteration does not interfere with imaginary surfaces you will receive a letter from MassDOT and a postcard from the FAA stating that no hazard exists and you may begin construction. The FAA evaluations expire and will need to be re-submitted if the construction does not start in the allotted amount of time stated in the determination. The FAA also requires follow-up forms to be submitted during construction, or if the project is abandoned. If any changes occur in location or height you must notify MassDOT and the FAA.

Hazard Determination

If the proposed construction/alteration is determined to be a hazard to air navigation you will receive a detailed response from each agency describing the measures that would need to be taken for the construction or alteration to proceed. There are several actions that could be required including, but not limited to:

  • Lighting the obstruction
  • Flagging the obstruction
  • Moving the obstruction out of the imaginary surface
Marking Information

You can get more information on Obstruction Lighting and Markings from the FAA Advisory Circular 70/7460-1K on the FAA Website.

Additional Information

Solar Panel Projects

If you are thinking about installing solar panels on or around an airport there are risks beyond that of obstructing airspace. Reflectivity can cause glare and a brief loss of vision to pilots. Solar panels, no matter the height, need to be submitted for Airspace Review to analyze any potential hazard to air navigation. More information can be found in the FAA Solar Guide.

Other Resources
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