Tower lighting We all are aware of the regulations concerning the care and feeding of tower lights. A recent article described both the actions that must be taken to notify the applicable powers that be concerning lighting failures and the requirements for their repair. However, the existence and logic concerning such lights still seems to be a mystery to some.
When a tower is planned, one of the initial pieces of paperwork is to file FAA Form 7460-1 with that agency. That form is a Notice of Proposed Construction and is used to initiate the formal study to determine if a tower is possible at the desired location and height without causing a hazard to air navigation. The filing is not always necessary. The Rules and Regulations contain the criteria to determine if such notification is required. If the tower is under 200 feet AGL and is not near any aeronautical facilities, it does not need to be lighted or marked, nor does the FAA have to be notified. That means that construction can proceed, if no FCC Construction Permit is required, without concerns about hazards.
Watch out for proposed facilities There is a kicker here. The requirement concerning aviation facilities includes those facilities which have been planned and for which notification has been filed with the FAA. Without a bit of a study, it is sometimes difficult to know just where such facilities may be proposed. Unless it is obvious that no airport facility could possibly exist in the vicinity of the tower (hills away from town, etc.) file the form. Remember, an aeronautical facility can be other things than an airport. For example, the FAA is a bit touchy about transmitters located near their navigation or communications facilities. Filing is acceptable insurance and covers your back just in case something has been missed. If notification is not necessary, the FAA will return the form with that notation and you can proceed without worry.
The forms are filed with the area FAA office that is responsible for your state. The form and the name and address of the appropriate office are available from the FAA website (www.faa.gov). On the form, you can indicate the type of marking and lighting that would be preferred, including "none" for short towers. Again, if notification is not necessary, no marking or lighting will be required. By the way, the term "marking" refers to painting the tower with the customary seven stripes of international orange and white. All painted towers now have seven stripes of equal width with the top and bottom being orange.
If the FAA determines that your notification was necessary, they will perform the study to determine the possible impact of the tower on aeronautical navigation. This will include the approaches to area airports, which also considers all instrument approach, departure and missed approach paths, proximity to airways and proximity to Visual Flight Rules (VFR) flyways.
A VFR flyway is anything that pilots may elect to use as a navigational aid in times of marginal flying conditions. If over noncongested areas, a pilot may legally fly at 500 feet above the ground. During marginal flying conditions, when the ceiling is over 1000 feet above ground and the visibility is three miles or more in controlled airspace, a pilot may elect to follow a road, river or railroad that he may know will guide him to a desired location. If the proposed tower is not over 500' AGL, the tower will not normally be considered to have any impact on such visual flight rule flights. Anything over 500 feet AGL will automatically be considered to be a hazard if within two miles of a VFR flyway and will require circularization to all concerned parties for comments. The two-mile margin accepts the fact that pilots have learned to stay to one side of such flyways. If they fly right down the middle, they run the risk of meeting another equally stupid pilot coming the other way.
Assuming that everything goes well with the FAA study, a Notice of No Hazard will be issued. The cute part here is that the FAA determination of whether or not a proposed structure would be a hazard is their opinion and acts to recommend to other agencies whether a tower should be approved. As an opinion, it is not subject to review in the courts. That is to say, if you receive a determination that a tower is a hazard, the FCC will not issue a construction permit. You are done at that site unless you make changes and reapply.
If a determination of no hazard is made, the FAA will recommend the desired lighting and marking. On many structures, the proponent is given the choice of either strobes or conventional (red) lights with painting. The FCC, when issuing the construction permit (if any) will often give that option to the applicant. Where no construction permit is required, as in those cases where a company is going to build a tower simply to lease space to others, the owner can rely on the FAA determination to pick the lighting and/or marking scheme.
Strobes vs. conventional lighting There was a period of time when strobes were considered to be the lighting plan du jour. Every tall structure was specified with high-intensity white lights. There was only one little problem with this scheme of things - the citizenry screamed like mad. It turns out that many people don't like looking out at strobes at night. During the day, such lights seem to be largely acceptable. But, at nighttime, a large portion of the populace finds them to be offensive. As a result, elected officials started getting lots of complaints. That resulted in cries of protest to licensees, the FCC and the FAA. The outcome was a tempering of the use of high-intensity strobes or medium-intensity strobes for shorter towers.
It was also thought for some time that high-intensity strobes aided aeronautical safety by making the towers more visible to pilots at night. It was later shown in some studies that the advantage was not as great as originally thought. It seems that pilots would fixate on avoiding a big strobe lit tower and miss other structures that had red lights. In other words, they would be so careful to watch out for the strobe lit tower that they were in danger of hitting other towers. They might be congratulated for missing the 2000-foot tower and only hitting a 1000-foot tower. Certainly, such pilots felt much better for their actions.
An additional reaction to the one time mass shift to high-intensity lighting has been the modification of building codes in many areas. Elected officials are highly responsive to complaints from the residents of their districts who vote for them. As a result, many building codes now require that towers have either red lights and paint or dual lighting systems that use red lights at night. Many broadcasters prefer such a system as well. They don't have the expense of maintaining the paint on the towers and they avoid the complaints of those who live in the vicinity of their towers.
One other major factor has become involved in tower lighting schemes: Environmental organizations have become largely resistant to strobe lights at night. There is a strong argument that such lights are hazardous to birds that may reside in the area or that may fly through the area when migrating. You haven't lived until you have listened to nature lovers who have found a bald eagle lying near a tower with a broken neck. That concern, while realistic, has been questioned in the past. For example, a two-year study of dead birds found around two tall towers in Iowa found that no birds were found that were listed as either endangered or concerned species. On the other hand, many of those birds where listed by the Department of Agriculture as disease carriers and common pests. Based on those results, it could be argued that the towers were providing a service to the community. It is an argument doomed to be greeted with scorn as happened when this author presented it at a zoning board meeting (with tongue planted firmly in cheek).
Still, the bird kill concern must be considered. In areas where birds such as the bald eagle are common or along well-known migratory flyways, special thought should be given to the use of dual lighting, even for very tall towers. These concerns have to be balanced with the high priority of aeronautical safety as well as the wishes of the public. As both the FAA and FCC are governmental concerns, they do respond to public input and to the comments of legislators (especially the latter). If at all possible, they will attempt to call for the use of the less obtrusive use of dual lighting when requested.
To summarize, don't hesitate to make your case for the type of lighting you would prefer on your proposed tower. Take into consideration the local requirements and the likely response of your management to complaints from the public. As a general rule, if you use straight strobe lights on your tower, you will receive complaints.