Airport Evaluation

Sometime during the planning stages and prior to filing application with the Federal Aviation Administration (FAA) and eventually with the Federal Communications Commission (FCC), a Preliminary Airport Evaluation is conducted to uncover potential impact to air navigation at a location that proposes to construct a tower, pole, mass, water tank, windmill, wind turbine (FAA only), or any other structure that penetrates near airport, on airport, height or flight instrument restrictions.  The evaluation is conducted strictly as an analysis of the airspace and obstacles in the surrounding vicinity of the proposed structure and is not to be construed as an FAA final determination of no hazard to airspace.

Airport Evaluations should be conducted in accordance with the Federal Aviation Administration (FAA) Regulations FAR Part 77 and the Federal Communications Commission (FCC) Rules Part 17 rules and regulations.  The client (tower/structure owner or proponent) supplies the Evaluating Agent (Federal Airspace Specialist) with the following information: 

• Structure address or directions
• Structure type (tower, antenna tower, water tank, mass, pole, windmill, wind turbine, etc.)
• Latitude and longitude (usually depicted on a certified 1A or 2C survey)
• Ground elevation (also depicted on the certified 1A or 2C survey)
• Structure height
• Overall height (including all appurtenances, such as lightning rods)
• A 1A or 2C survey

The Federal Airspace Specialist then takes the provided information and conducts an analysis based on FAA/FCC standards, online programs, specialized software, U.S. Terminal Procedures, and various calculations.  Among other components, the Analysis should include the proposed structure's:

• Initial impact with the nearest Public-Use Airport, the nearest runway, and/or the nearest Heliport.
• Overall height of 200 feet (Above Ground Level) when compared to the FAR 77.13 (a) (1) standard.
• Airport slope or imaginary surface extending outward and upward at one of the following slopes:  (i) 100:1 for a horizontal distance of 20,000 feet from the nearest point of the nearest runway with at least one runway more than 3,200 feet in actual length, excluding heliports, (ii) 50:1 for a horizontal distance of 10,000 feet from the nearest point of the nearest runway with its longest runway no more than 3,200 feet in actual length, excluding heliports, (iii) 25:1 for a horizontal distance of 5,000 feet from the nearest point of the nearest landing and takeoff area of each heliport specified (FAR 77.13 (a) (2)).
• Nearest airport Instrument Approach Area (FAR 77.13(a)(4)).
• Height of 500 feet (Above Ground Level) when compared to FAR 77.23(a)(1).
• Height of 200 feet (Above Ground Level) or above the established airport elevation, whichever is higher, within 3 nautical miles of the established reference point of an airport, excluding heliports, with its longest runway more than 3,200 feet in actual length, and that height increases in the proportion of 100 feet for each additional nautical mile of distance from the airport up to a maximum of 500 feet (FAR 77.23(a)(2)).
• Near airport Initial Approach Segment, a departure area or a circling approach area that would impact the Required Obstacle Clearance (ROC) (FAR 77.23(a)(3)).
• Near airport En-Route Minimum Obstacle Clearance Area (MOCA) (FAR 77.23(a)(4)).
• Near airport Horizontal surface (FAR 77.25(a)).
• Near airport Conical surface (FAR 77.25(b)).
• Near airport Primary surface (FAR 77.25(c)).
• Near airport Approach surface (FAR 77.25(d)).
• Near airport Transitional surface (FAR 77.25(e)).
• Near military airport imaginary surfaces (FAR 77.28(a)(b)).
• Proposed location and height compared with existing FCC Antenna Structure Registration (ASR) registered structures within a three-mile radius.
• Impact with AM towers.

Although the FAA does not study Private-Use landing facilities, sometimes an efficient Preliminary Airport Evaluation will state the location of such a facility if it sits within three (3) nautical miles of the proposed structure location. The inclusion of Private-Use landing facilities informs the structure owner that new construction may produce inquiries and public comments related to air navigation at these facilities.

After a thorough investigation of the proposed structure has been performed, the resulting information is compiled into a report called the "Preliminary Airport Evaluation."  The report should include a summary of the results and suggestions/recommendations that pertain to (a)  the proposed structure exceeding/not exceeding FAR standards, (b) the structure owner's decision to file or not to file with the federal authorities, (c) further services provided by the Federal Airspace Specialist and Company, and (d) a signature and date by the Analyst.  Once completed, the Preliminary Airport Evaluation is then presented to the client for review.

Most Evaluations do not include a frequency or marking/lighting study.  As stated earlier, a Preliminary Airport Evaluation should not be interpreted as the FAA's final determination or opinion.   All new proposed structures should be filed with the FAA and later with the FCC (wind turbines and structures that do not radiate frequencies/power are not subject to the FCC ASR process) to determine structure height and air navigation obstruction impact through the airspace analysis process regardless of impact or no impact to air navigation.  Below are a few great reasons to file with the federal authorities (FAA/FCC):

• The plotting of structures on flight maps may prevent unnecessary airplane crashes.
• New structures are included in the FAA's and the FCC's online databases to view by the public, pilots, local and state officials. Search perimeters include by latitude/longitude, FCC ASR number, city/state, structure owner's zip code, or by overall height above ground.
• Potential prospects looking to co-locate on existing structures can search the online databases to locate structures, their overall structure height and lighting/marking and ownership information.
• Certain navigational aids may extend as far as 12 nautical miles from the nearest Public-Use landing facility (airport).
• Allowing the FAA to determine structure height and air navigation obstruction impact through the airspace analysis process prevents construction delays and post-build glitches between the new structure and the feds, public, local officials, and pilots.
• The FAA recommends lighting/marking standards for individual structures based upon their analysis that allow peaceful co-existence with the surrounding communities.  How would you like trying to sleep while a flashing medium or high-intensity white strobe light blinks through your windows?  Check out the FAA's Advisory Circular on Obstruction Marking and Lighting.
• The FAA conducts a thorough study of frequencies that are not contained in most Preliminary Airport Evaluations.

Acquiring a Preliminary Airport Evaluation can save time and money when constructing a new structure that may impact air navigation by any of the federal standards stated above.

AIR IMPACT EXAMPLE
You are proposing to construct a structure that is 150 feet AGL.  After reviewing the Preliminary Airport Evaluation, the proposed structure exceeds the airport slope by 45 feet at an airport that has at least one runway that is 3,200 feet long (100:1).   This information is critical, because you realize that the FAA may not approve the structure at 150 feet AGL, but may require the structure height be lowered to 125 to 130 feet AGL or be placed on Public Notice (which can take up to six months to finalize).  Even after Public Notice period is completed, you may still be required to lower the overall structure height of your proposal.  The resulting outcome of the Preliminary Airport Evaluation has produced a decision-making analogy: 

• Can we lower the structure height and still meet our objectives?
• Are we prepared to wait up to six months for FAA approval (after FAA determination is made, you will then file with the FCC for an Antenna Structure Registration number, which can take another 45 days)?
• Should we pursue this proposed structure location or make plans to relocate the structure to a more amiable location (for which a new Search Ring Analysis and Preliminary Airport Evaluation are generated)?

SUMMARY

As you can see, the Preliminary Airport Evaluation is detrimental to your timeline for constructing a new proposed structure.  The Analysis virtually prevents added time and cost to the construction budget, exposes potential construction obstacles, and offers professional advice for alternative plans.  For these reasons, the Preliminary Airport Evaluation is essential to the long-term operation of your project.

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