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ALTA "Conical Zones" and "airport proximity"
Posted by dmyhill on September 2, 2016 at 6:07 pmOn Table A, Item 21, the following was specified:
“show conical zones, the proximity of any airports and the heights of improvements which may be constructed in such a conical zone”Seems reasonable, but somehow I have never done this, does anyone have a comment how they have dealt with this in the past?
The site is located in Newcastle, Washington, if that makes any difference.
(I have looked at the FAA site, but it has been slow going finding appropriate resources.)
Thanks,
Davidjitterboogie replied 3 years, 7 months ago 15 Members · 19 Replies -
19 Replies
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been a while, but i did a site for a proposed hospital about 10 years ago that was wedged between a private and a military airport.
don’t remember exactly how it was dealt with, but yeah, it basically involved a bunch of notes quoting FAA info. of course this thing was also covered in multiple avigation easements and height restrictions, so that may have made it easier.
ed- the hospital project fell apart, btw. don’t think anything has ever gone in there.
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We’re lucky here in Oklahoma as “vertical approach” easements and ordinances are filed of record and easily obtainable.
Most (if not all) are either circular or begin at the end of the R/W and proceed at a stated slope. I believe the FAA has a publication on determining the physical center of an AP operation.
On ALTA surveys within these areas I have shown a large scale map of the easement concentrics also showing the subject property location, and noting whether or not there is any improvements upon the property that conflict with the vertical limits of the ordinance or easement. I’ve never gotten too excited about them as they are common in this part of the country.
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http://www.wsdot.wa.gov/data/tools/geoportal/?config=airport
There is this, which shows the information, but I have had a difficult time finding the FAA documents it is based on.
-All thoughts my own, except my typos and when I am wrong. -
I don’t know whether this is relevant but the FAA document describing obstructions to navigable airspaces is here: http://www.ngs.noaa.gov/AERO/FAA405part1.pdf
See section 2.
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The things a person can find on this site are downright unbelievable.
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dmyhill, post: 389403, member: 1137 wrote: On Table A, Item 21, the following was specified:
“show conical zones, the proximity of any airports and the heights of improvements which may be constructed in such a conical zone”Seems reasonable, but somehow I have never done this, does anyone have a comment how they have dealt with this in the past?
The site is located in Newcastle, Washington, if that makes any difference.
(I have looked at the FAA site, but it has been slow going finding appropriate resources.)
Thanks,
DavidI did an ALTA about five years ago on a site that had a large tower. It was no where near tall enough to ever worry about it, but I had to do the same thing your doing. I went to the airport and spoke with a very helpful fellow. He was able to get me all the info I needed and he was excited just to see someone. This was a small port and he was bored.
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Adam, post: 389472, member: 8900 wrote: Has anyone ever found anything obstructing their space?
Sure. Did a number of “obstruction surveys” for various APs around Oklahoma a few years back. Power lines, civil defense sirens, comm towers and even a couple of silos at an asphalt plant. Never did an ALTA that had any structures that impeded the airspace restrictions though.
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Adam, post: 389472, member: 8900 wrote: Has anyone ever found anything obstructing their space?
Adam,
I had to do a survey on a tower in Charlotte that got extended more than was approved and was causing problems for planes in the holding pattern around the Charlotte airport.
Ed
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A decade or so ago I did an obstruction survey for a small airport because of some trees. I guess someone at the FAA thought they looked like they might be in the flight path. My recollection is that they were clear of the critical lines.
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[USER=1137]@dmyhill[/USER]
I have had to show the approach zones on a drawing of the local airports back in the 70s and 80s when they were gathering grants for expansion.
We were installing the visual approach slope indicators (VASI) and other required upgrades.
Had to find out and show an arrow about the prevailing winds of the location. -
We’ve had to shoot church steeples and tall palm trees in the approach path. The bottom of the critical path is more of a wedge from the end of the runway, but it does flare out as well..
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If there is an avigation easement, the restrictions should be stated. If not, you will need the FAA approved Airport Layout Plan (ALP). The ALP will define the glide slope and runway protection zone. These are not standard, as it will be based on the Class of aircraft for which the airport was approved. I recommend coordinating with the Airport Manager’s Office to determine the specific requirements. The AP Manager is always interested in anything near the end of the runway. In some cases, we had to actually locate the threshold on each end of the runway. This may require coordination with FAA and a formal aircraft advisory and or runway shutdown. At a commercial airport, you may need to increase your insurance, have your crew obtain who knows how many safety certificates and pass an extensive security check. It may be as simple as getting a copy of the ALP and getting on the same horizontal and vertical datum. The Airport Engineer that prepared the ALP has always been very helpful. However since 911, all airports have become very sensitive about security and releasing information.
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Nice presentation plenty of graphics on airport obstruction charting here:
http://www.wsdot.wa.gov/NR/rdonlyres/2CFA42E4-2718-4884-8FD3-AD2000491AE6/0/FAA_Part77_Basics.pdf
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Conical zones and the Trapezoidal runway protection zone (wedge) are illustrated on page 32 of FAA no 405 “Standards for Aeronautical Surveys” (part 1). See also FAR part 77.17 – Obstruction Standards
My airport is dealing with trees in the approach for which they have to maintain a safe height. Best I can come up with is I will locate the trees and measure height of each tree then create a 3d CAD model of the zones and identify which trees penetrate the approach surfaces and how much they need to be trimmed off the top in order to comply.
Anyone have any better ideas?
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Posted by: @david-kendall
Best I can come up with is I will locate the trees and measure height of each tree then create a 3d CAD model of the zones and identify which trees penetrate the approach surfaces and how much they need to be trimmed off the top in order to comply.
I’d say that’s the easiest way. When I did AGIS surveys 5-7 years ago, the analysis was done in GIS (we had points that had been extracted from aerial photogrammetry), but we built all the surfaces in C3D.
Build the surface, then bring in your points, run the “elevations from surface” command on the points, export them back out again as a different file, and then compare elevations in Excel. Negative values indicate a penetrating tree, plus the amount to be trimmed.
“…people will come to love their oppression, to adore the technologies that undo their capacities to think.” -Neil Postman -
Done several airport surveys involving calculating clearance of the approach/takeoff wedge(s) for adjacent development height obstructions, it’s easy 3D math and the airport provided the model. Also have done proximity surveys to determine whether a prohibited business would be too close to the approach/takeoff pattern, a movie theater for example.
But the craziest airport work I’ve done was as a sub for a mega engineering outfit rehabbing the concrete on one of the 4 strips at LAX. They were required to hire local for a percentage of their contract, i.e., us; we had to get special insurance, drug testing, submit to personal wage & time reports, etc. Had to go through the airport’s safety training (just like working on railroads). Everybody’s badges were checked out at the special gate and a quick look see of our rigs was done. Was always accompanied by two flagger trucks who shepherded us like children. Of course no cones or flagging allowed, only paint & tags, and they were real jumpy about FOD.
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Perhaps the following might be useful. https://wsdot.wa.gov/sites/default/files/2006/12/13/aviation-far-part-77-basics.pdf
You mention surveying approaches; what about transitional surfaces. The page linked above includes many useful graphics. The NGS Remote Sensing Division includes links to their obstruction charts in .dgn format.
https://www.ngs.noaa.gov/AERO/uddf/info/405change1.pdf
https://geodesy.noaa.gov/web/AERO/aerodata.shtml
https://www.ngs.noaa.gov/AERO/charts.shtml
Are your obstruction heights wrt the runway height?
Looking at the NGS site reveals many broken links.
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This will be onerous, but what isnt at the federal level. I’ll browse my files at the office in the morning, I’m working in this environment now for the forseeable future.
http://www.faa.gov/documentLibrary/media/Advisory_Circular/150-5300-13A-chg1-interactive-201907.pdf
and the rest of the flotsam:
https://www.faa.gov/search/?omni=MainSearch&q=conical+zones
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