[TowerTalk] FAA & Private Air Strips

[Fred Kleber]

It is very important to determine if the airport is a private or commercial airport.  This can conveniently be done at:
 
https://oeaaa.faa.gov/oeaaa/external/searchAction.jsp?action=showCircleSearchAirportsForm
 
Private airports are just that and do not have the "protection" from the FAA that public airports do.  So why would people have private airports?  They are exempt from a LOT of FAA red tape.  
 
I would not talk to the owner of the private airport until you have your FAA approval in hand.  With this, the FAA has spoken and he/she can't go and raise a stink that could possibly cost you some time/money.  Believe me, I have seen it happen...
 
In the commercial wireless industry, it is nearly standard practice to have a surveyor provide a letter with coordinates.  Coordinates are generally at least "2C" (50' horiz & 20' vertical) accuracy and most of the carriers have moved to "1A" (20' horizontal & 3' vertical) accuracy.  I am guessing this is most likely due to potential liability issues.  Here's a link that will tell you about this...
 
https://oeaaa.faa.gov/oeaaa/external/content/surveyAccuracy.jsp
 
Per the FAA at the link above, 
 

"Experience has shown that submissions often contain elevation and/or location errors. Current directives require the FAA to apply accuracy standards to obstacles when evaluating effects on instrument procedures. These accuracy standards typically require a 4D adjustment of 250 feet horizontally and 50 feet vertically to be applied in the most critical direction. Normally, these adjustments are applied to those structures that may become the controlling obstructions and are applicable until their elevation is verified by survey. 
 
In these instances, the acceptable accuracy verification method will be requested by the FAA to pursue a favorable determination. A licensed engineer or surveyor must certify the provided survey accuracy and include the plus or minus accuracy required, as well as, the signature of the engineer/surveyor and the appropriate seal. A final determination based on improved accuracy shall not be issued until after the certified survey is received.
  
During the aeronautical study process, the FAA may request a certified survey with an accuracy of either 1A (+20 ft horizontally +3 ft vertically) or 2C (+50 ft horizontally +20 ft vertically)."
 
In reality, I'd use as many sources as you can and take your best guess.  It's probably not as critical as everyone thinks it is.  The reason the FAA would likely ask for a 2C or 1A survey would be if you are on the side of a very steep sloping hill.  Being off by 50 or 100 feet of horizontal distance could have a profound effect on ground elevation, versus if you were on relatively flat terrain.  Proximity to the limits of an airfield also can influence this decision.  
 
There are two glide-slope radios that are generally applied for a rough analysis:  1:20 and 1:50.  The 1:20 ratio is for airports with shorter runways, (3700 feet I think), and the 1:50 is applied to longer runways.  Whether the airport has a heliport also influences their analysis.  
 
The geometry of the "clear space" around an airport can roughly be described as follows:
 
*  Take an oval shaped football stadium with the runway axis running down the middle of the stadium
*  Lower the height of the rounded ends of the virtual stadium.  (These are the paths where the planes take off & land)  
 
There are several other approval portions of FAA filings which have not been discussed.  I think there are 7 or 8 of them.  (Historical, EPA, Intermod, etc.)  Regarding the intermod part, FAA filings also require submitting field strength ERP data for any frequency on which you may operate.  The FAA's presumably antiquated RF intermod modeling tools only dealt with discrete frequencies, so you can imagine their confusion when I said I would operate on any, and all, amateur frequencies with the maximum power permitted.  (1500w)  In San Diego they finally had me talk to the intermod analysis tech and agree that I would keep any VHF spurs on the tower frequency below -122 dBm.  I wrote a letter to this effect and they were fine with it.  
 
In Florida, the intermod tech also happened to be a ham.  Unfortunately he happened to be a shack-on-a-belt type.  I had three "hits" on 40m, 80m & 160m.  He said that if I would limit my ERP to 25w on 160m and 50w on 40/80m, he could issue a no-hazard determination.  He mistakenly was of the impression that "nobody uses those frequencies anyway".  
 
I asked to see their analysis model.  Why 160m I wondered?  LORAN, which is no longer in use, was the answer.  I think it was developed by Univ of MI, but the FAA would not back down.  I told them to cancel my request and that I would build my tower one foot below the "no-notice" height and run all the power I am legally allowed to.  BTW, a no-notice estimation tool is available at:
 
https://oeaaa.faa.gov/oeaaa/external/gisTools/gisAction.jsp?action=showNoNoticeRequiredToolForm
 
Any structure 200 feet, or taller, requires lighting and/or marking according to FAA requirements.  Shorter structures can also have this same requirement, depending on their proximity to an airport / flight paths.  Lighting can be any combo of the following:
 
* Painting the structure
* Constant red beacon
* Flashing red beacon
* White strobes - low intensity
* White strobes - high intensity
* Spheres on the guy wires (very seldom)  
 
Additionally, any structure that is required to be lit is also required to be monitored.  The FAA's national NOTAM center is required to be notified within 15 minutes of any lighting outage.  Also, any tower that is lit is also required to have a quarterly inspection to verify functionality of the lighting and alarm monitoring systems.  If the tower is at your house, visual monitoring is generally acceptable.  
 
To the person talking about the plane that hit the power lines, I have personally been through a tragic situation such as this.  An inexperienced pilot was taking his friend and his family to a college football game and evidently flew below the clouds as he was not instrument rated.  He yanked a guy wire off the tower and landed 1600 feet downrange in a twisted mass of guy wires & airplanes.  Unfortunately all on board the aircraft perished.  Dealing with the FAA and all of the lawyers was not a fun experience either. 
 
Hope this helps & hope to work the big AA7XT (why 7 land?) signal soon!  
 
Very 73,
Fred, K9VV / NP2X