Low-Level Tower Q & A

What are the legal marking requirements for towers under 200 feet?

Under the 2018 FAA Reauthorization that President Trump signed into law, Meteorological Evaluation Towers (METs) between 50 and 200 feet with an above ground base of less than 10 feet in diameter in rural areas must be both marked and logged into a database accessible to aerial applicators. Communication towers meeting these same requirements have the option to be marked or logged into the database. The FAA is currently working on promulgating the marking requirements and establishing this database.
When will the database be up and running?
The 2018 FAA Reauthorization requires the database be accessible to aerial applicators by October 2019. NAAA is working closely with the FAA to ensure they meet this deadline, and to ensure the database will be a practical and user-friendly tool. 
Why are these towers subject to marking and/or database requirements?
METs are used for gathering wind data during the development and siting of wind energy conversion facilities. They are also used during wind conversion operations. The type of METs used before the construction of a wind site consist of sections of galvanized tubing that are assembled at the site and raised and supported using guy wires. They can be erected or removed in as little as three hours. The tower may be at one location for a short period of time and then moved to a different location, as the wind company checks the area for the best wind conditions for the placement of wind turbines. Since they are lightweight and portable, they do not leave a visible footprint on the ground. They may be found in cropland or non-cropland areas.
Much like METs, real-time kinematic (RTK) towers and communication towers are expected to grow exponentially. RTK towers supplement the GPS systems of automated ground-based farm equipment and as a result are found almost exclusively in rural areas. With the increasing popularity of automated and semi-automated ground-based farm equipment, RTK towers are anticipated to become more numerous each year.
Additionally in 2000 there were 60,000 towers for wireless communication in the U.S. Today there are 150,000; by 2025 200,000 are expected. In addition to advocating for the proper marking of communication towers, NAAA is also encouraging USDA to utilize existing infrastructure when it builds rural wireless networks, such as small-cell antennas that can be mounted on existing utility poles, the facades of buildings, and building rooftops. NAAA also strongly supports any communication systems that can be laid underground without adding obstructions to the National Airspace System (NAS).
All these towers tend to be narrow, and grey in color which makes for a structure that is nearly invisible under some atmospheric conditions. Sadly, aircraft collisions with towers usually result in fatal injuries. NAAA convinced Congress to act to make these towers’ presence known to low flying aviators.  As such, federal law now exists requiring towers fitting this description should be marked and/or logged into a database.
It is NAAA’s position that all towers between 50 and 200 feet, no matter what their function, need to be both logged into a database and  marked. However, Congress bowed to the powerful communication’s industries’ concerns over the cost of tower marking and gave non-METs the option to either be marked or logged into the database.
There is still hope to broaden the law to mandate marking for all towers fitting this description.  Shortly after Congress exempted non-METs from the same requirements as METs, the NTSB re-issued a newly revised Safety Alert “The Hazards of Unmarked Towers” (SA-016). This safety alert urged pilots to be vigilant for unmarked METs and other unmarked towers, such as GPS functionality and telecommunications towers. The original safety alert issued 7 years ago warned of only unmarked METs but the NTSB and low-altitude aviation industry has since realized other unmarked towers create hazards as well. This revised alert warns low-altitude pilots of this additional danger.
NAAA has brought this revised safety alert to Congress as further evidence all towers between 50 and 200 feet must be marked.
Suggested operating procedures regarding towers:
  • Ferry above 500 feet, even in sparsely populated areas.
  • Think inside the box: establish a box that contains the area where you are working plus the turnaround area. Make sure that you inspect that area for obstructions while still at altitude, then stay in that box while conducting operations including entering and exiting the area.
  • When working within or near wind turbine sites, do not become so concentrated on the large turbines that you miss something smaller such as a MET. Most operating wind conversion facilities have one or more MET testing towers located within them.
Other ways to mitigate this problem:
  • Work with your customer/landowner not to erect towers on their land, not only for your safety as an ag pilot, but also because it takes land out of production and a tower may prevent the cropland from being treated or put last in the queue for an ag pilot to treat due to its perilous nature.
  • If your customer/landowner signs a contract with a wind developer, let them know METs must be both properly marked and logged into the FAA’s database.