Saturday, May 26, 2018

Ask Us: Feds set rules lights on towers, smoke stacks

Q: Dear Mr. Ask Us Guy,

Just curious. A number of years ago a communications tower was built on the north end of lower North Mankato. It had an off/on red light at night and an off/on white light during the day. For about a couple years now, it has no lights flashing at all.

To the west on the top of North Mankato is another communications tower that has an off/on red light day and night. North of Mankato is another tower that has a steady red light. And the chimney at ADM has a strong flashing white light day and night.

Question: What's the reasoning and who regulates as to what lights on what structures?

A: The Federal Communications Commission regulates communications towers and consults with the Federal Aviation Administration when construction of a tower is proposed.

"If the FAA determines that the tower would be a physical hazard, the FCC will not approve the construction permit application," according to the FCC website.

If a tower is approved, specific requirements are imposed about the color of the tower and the placement of red lights at certain intervals to prevent the tower from being a "menace to air navigation."

Generally, the towers must be painted intermittently in white and red/orange to make them visible during the day, with paint tones (including white) specifically and precisely mandated by the federal regulations. One red light (an "L-864 red medium intensity beacon" in fed-speak) is required at the top of all towers, according to the website of Flash Technology, a Tennessee company that supplies tower lights. For towers taller than 350 feet, a pair of the red beacons are required at each 350-foot point in addition to the beacon on the top.

The FCC, however, frequently allows an alternative to the painting requirements and the red beacons — synchronized flashing white lights. A white beacon must be on top and a trio of white lights pointing in different directions at 350-foot increments from the ground, according to the Flash Technology website.

So, if you're wondering how tall a tower is, you could count the number of segments between the lights from the ground to the top and multiply by 350 feet and have a pretty good idea (unless the tower owner decided to add extra lights beyond what's generally required.)

As for the reader's suggestion that the lights are no longer flashing on the tower in lower North Mankato, Ask Us Guy can only guess that the tower owner received a waiver from the FCC. There is a special procedure for lighting requirements in residential neighborhoods.

Without a waiver, tower owners not only are required to have lights, they are required to record any problems with the performance of their warning lights, including the time and date of repairs.

Finally, the smoke stack at the ADM plant ... . Ask Us Guy decided against climbing it with a tape measure, and he's not sure if the FAA regulates it. But anything 200 feet or taller generally needs to be lighted under the guidelines of the FAA and the International Civil Aviation Organization. Shorter structures, including water towers, might need lights if they're in proximity to an airport.

Original article ➤

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