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jdunmyer
11-06-2009, 08:46 PM
I've noticed that radio towers seem to have either white strobes or red lights for aircraft warning, but with seemingly no rhyme nor reason. Short towers may have red lights, but others may have strobes. The smokestacks at the power plant have strobes, but tall radio towers seem to usually have red lights. A quick search didn't turn up anything useful, so I am turning to the vast knowlege base here.

Anyone know what the deal is?

SteveF
11-06-2009, 08:55 PM
All you ever wanted to know.

http://www.faa.gov/about/office_org/headquarters_offices/ato/service_units/systemops/fs/alaskan/towers/obstruction/media/AC70_7460_1K.pdf

Steve.

Evan
11-06-2009, 09:11 PM
There are several reasons. The location plays a part. Major airports are surrounded by a zone called the Terminal Control Area. Within that area a range of regulations pertain to anything that could be a hazard to air traffic including structure lighting and height and even how they are aligned with the runways. The restrictions are based on distance from the airport as well. A further consideration is the existence of migratory bird flyways in the vicinity. Birds are attracted to lights at night, especially strobe lights. It is thought that they use them for navigation but they then run into guy wires that surround tall towers. Those towers will usually be marked with red lights as they are not as attractive to birds and are less disorienting.

Most low towers will be marked with red lights unless they are close to a TCA or directly on a flight path. Really tall towers such as the LORAN C tower near us are marked with multiple strobes at several different altitudes since they may be mistaken for aircraft if marked with only a single light or strobe. The closer a structure is to the airport the lower the minimum height at which marker lights must be installed.

I gave up on the FAA document. Takes too long to download.

rdfeil
11-06-2009, 11:49 PM
Follow Steve's link and be prepared for some reading. Tower lighting and painting in the US is strictly enforced by the FAA and the FCC actually is submissive to them when it comes to tower issues. The type of lighting is determined by height of the tower. The strobe or red light is determined by the tower owners. Both types of lighting are legal in the US. Many towers are now lighted with strobes as the life span of the strobes greatly exceeds the incandescent light bulbs. Another thing is that some towers are actually lighted by both types of light. Usually strobes in the day and red bulbs at night. The strobes are easier to see in the daylight and the red bulbs are less annoying to the neighbors at night.

Robin

Paul Alciatore
11-07-2009, 01:05 AM
I am a TV engineer by profession and have been responsible for several tall towers in my career. No, I never climbed them.

In the US, any tower 150 feet high or taller must have lights and a means of knowing that at least the beacons are working. Any non-functioning lights must be reported to the nearest FAA office or airport ASAP. Most (all with tall towers) TV and radio stations have daily inspections of some sort. This may be a visual observation after dark or a current sensing circuit or whatever. This IS basically an FAA thing to protect aircraft. It is incorporated into FCC rules but the FAA will also require lights on other tall structures.

Red vs Strobes. Originally the lights were red as there were no strobes. Some, like the top beacon, blinked to better attract attention (wake up the pilots) and some were constant. Somewhere around the 60s or 70s they came up with strobes (the white ones). They are expensive - more so than the incandescents. Today, new towers have strobes. But the older incandescent lights (the red ones) were grand fathered in due to the cost factor. That's why you see both red and white ones.

I haven't been with a TV station for about 15 years now so some things may have changed. It is possible that some new shorter towers may be permitted with the red lights. But with the conversion away from incandescent lighting, I doubt it.

Other facts:

The number of lights is determined by the height of the tower. Basically, there is a maximum distance between lights, but I don't know exactly what is is. It could be determined form the charts in the regs.

The frequency of the top beacons' blinking was controlled so pilots would be able to tell which tower they were observing. And, no, I don't know if they ever actually used this, but that is/was the reasoning.

Tower crews, when changing bulbs just love to toss the old ones off the tower and watch them crash. The land around many tall towers is probably rich in tungsten.

macona
11-07-2009, 01:36 AM
So maybe someone knows this. How are the light and strobes powered on high tension towers? Do they just catch the bleeding electricity from the power lines?

Evan
11-07-2009, 03:43 AM
Do they just catch the bleeding electricity from the power lines?


That effect has been exploited to power lights in the big ball markers that are used to mark long spans over valleys and rivers.

BudB
11-07-2009, 06:18 AM
Many of the tall towers around here display strobes turing daylight and fog and blinking red at night.

jdunmyer
11-07-2009, 10:56 AM
Steve,
Thanks for the link, that was interesting (albeit tedious) reading. As Robin points out, it is kinda up to the tower owners as to which lighting they wish to use, within some general guidelines. That's why I was confused.

Thanks again, fellas!

<<Jim>>

mototed
11-07-2009, 12:19 PM
Many years ago when the station I worked at (we were using a subcarrier of of FM) the engineer told me that towers with strobes did not have to be painted. (red and white) They could be galvanized, but the strobes were lit 24 hours. Painted towers didn't have to illuminated during daylight hours. On a side note, I saw a tower being repainted once, they were using a fuzzy glove on one hand as the bush.