It is very important to determine if the airport is a private or commercial
airport. This can conveniently be done at:
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
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
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
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
* 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:
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!
Fred, K9VV / NP2X
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