Has anyone recently done any work under the FAA Advisory Circulars for 150/5300-17B?
Yes I put 17C in the title but 17C supersedes 17B with the addition of LIDAR. I don't have a concern about that, but what I do need clarification on is the OPUS requirement for the Aerial target control, which has not changed from B to C.
The AC states that the position must be derived by OPUS and we have to provide a copy of that OPUS solution in the final report.
It does not state the time interval of the data collection. If not, I'm wondering if I can use OPUS-RS for the solution? Rather than using the standards for airport geodetic control, which this does not fall under those guidelines, 2 or 3 redundant visits to a point should be quicker than a full single 4 hour solution.
Anyone have any opinions? (Page 10 and 14 of FAA AC 150/5300-17C.)
I would be surprised if the FAA and NGS would accept something less than 4 hours' occupation for that important a position. They do multiple day's worth of observations just for benchmarks.
Any project that I've been involved with requiring OPUS solutions to be submitted has required a minimum 4 hr solution submitted to OPUS-DB. The deliverable would be the DB datasheet.
There's nowhere in the AC that states an occupation time. I just read AC 16A yesterday which clearly states a minimum of 4 hours for Geodetic Control AT the airport. PACS / SACS.
In AC 17C on pg 10 one of their examples of a "well defined" control point is the corner of a concrete driveway next to an asphalt road. That does not seem important for regular surveying standards to me.
Maybe I missed something in 16A about "non-geodetic" control.
4 hours for panel points is silly. It would be much better to have multiple occupations and connect them to control derived by OPUS. If you set on it only one time you will have no proof that you were over the point and that you measured the correct HI. It's a measurement that requires reduntant occupations. And if you need 4 hours I guess that would be 8 hours on each target. Waste of time, big waste of time!
Howdy,
If you examine the referenced document Linked here you see on page 6 that the required accuracy for these PHOTO control points is 0.3 meters in both horizontal and vertical.
This is NOT geodetic control. It is intended to assist the photogrammetrists who create the Obstruction Charts and related products.
What occupation time is required to achieve this accuracy? I do not see this specified. I would insure that my solution met OPUS quality solution requirements. If my peak-to-peak errors were all better than 5cm, I would be happy.
As for redundant observations, the requirement for multiple photo control points means they are checked against one another in the photogrammetric process.
For definitive guidance, contact the Remote Sensing Division folks at NGS.
HTH,
DMM
> Howdy,
>
> If you examine the referenced document Linked here you see on page 6 that the required accuracy for these PHOTO control points is 0.3 meters in both horizontal and vertical.
>
It's a good thing you referenced that. Did you know that 17B has been canceled as of Sept 30...
Anyway I printed off 17C (revised 17B) and read through it last night and today. I must have somewhere along the line got eye fatigue 😉 and just realized that I was missing page 18. This is the page that now has the accuracy standards in Circular 17C.
And yes, it is 1 foot (0.3 meters).
I think we'll shoot for a HARN (to be on the NSRS) and a redundant tie to each point.