Perry (Wagener, SC) Airstrip Review, Part II

In consultation with Al Tyler and Sam Zimmerman, I have come up with the following plan to tame the wild-and-wooly Perry database ;-).

  • Establish a boundary based on Al Tyler’s flights out of Perry, and remove all airstrips/airports “well outside” the boundary (items close to the boundary will probably be included for completeness). This should eliminate at least 50 airstrips, if not more
  • Remove all obviously abandoned/missing airports/airstrips
  • Add in airports within the established boundary that are in the Spartanburg database, but not in the Perry database – primarily along the I-85 corridor north of Atlanta, and the I-75 corridor south of Atlanta.
  • Correct waypoint displacements as necessary.
  • Verify the result in Google Earth
  • Publish the result as the ‘Perrry14a’ database
  • Post a review of the new database to highlight any ‘problematic’ airports/airstrips from my personal point of view – after all, that’s why I got involved in this mess in the first place! ;-).

As usual, I’ll generate my own ‘Perry14_minus’ database which will be the above database minus any airports/airstrips that I personally think would be problematic for new my 18m wondership.  By removing them entirely from my personal database, I won’t wind up doing a final glide to a 15-meter wide airstrip in an 18m glider ;-).

Establish a boundary

When I first looked at the Perry database, I was astounded by the geographical coverage, and the sheer number of airports/airstrips – yikes!  Then I realized that Al Tyler, OLC slut extraordinaire, probably covers most of the Perry expanse during his car-launch megaflights with his ASG-29. So, I decided to try and establish a boundary based on Al’s flight history.  I pulled a couple of years worth of his flights off OLC and plotted them all in SeeYou, as shown below.

Al Tyler's OLC flights in recent years

Al Tyler’s OLC flights in recent years

As can be seen from the above, Al’s flights cover a huge expanse of real estate, but doesn’t go much past Columbia to the northeast, or much past St. George to the southeast, and stays inside a line from Savanah to Macon to Athens.  Using this as my guide, I established a boundary as shown below.

Proposed Perry database boundary

Proposed Perry database boundary

As you can see, the boundary contains pretty much all the database items to the south, but cuts off a sizable number of airports/airstrips to the north and northeast.  Wish I had thought of this *before* I reviewed all 250+ airstrips! ;-).

Remove all Airports/Airstrips outside the boundary

One of the file types generated by John Leibacher at his wonderful Worldwide Soaring Turnpoint Exchange is a ‘Comma Separated Variable’ (CSV) format, which can be read directly into Excel.  Also, the ‘Soaring Turnpoint Exchange’ (STX) type used by ClearNav is a tab-delimited type which can also easily be imported into Excel.  I like to use Excel, because there is a nifty tool available at Earth Point (https://www.earthpoint.us/ExcelToKml.aspx) that can convert a properly organized Excel file to KML, which can then be viewed in Google Earth (GE) for verification purposes.

The .CSV file has the latitude and longitude data needed for the Excel-to-KML conversion, but unfortunately it has a lot of extraneous stuff in it as well.  So, first I had to create a modified version of the file with only the desired columns, as shown below (both at the same 50% zoom level).

Original Perry .CSV file

Original Perry .CSV file

Modified Perry CSV File

Modified Perry CSV File

Using the modified .CSV file, I removed all the lines corresponding to airports/airstrips outside the boundary marked in GE.  I started at Charleston AFB down in the far southeast corner, and worked my way counter-clockwise around the boundary.  I started with 266 items, and after several iterations, pared it down by 85 items to 181 – yay!!

Remove all obviously abandoned/missing airports/airstrips

After clearing everything outside the boundary, I went back through my original review and removed all the obviously missing/abandoned airports/airstrips. This got me down another 11 items to 170 .#26 Judge Wil airstrip was among the missing/abandoned, but it can’t be removed as it is a contest turnpoint.  For it, I simply changed the code from ‘TL’ to ‘T’.  Note that I *did not* remove anything remotely landable, even though I will probably remove them from my personal database.  At this point, the Perry database looks like the following (the default icons are the result of the Excel-to-KML conversion)

Perry database after removing out-of-bounds and missing/abandonded airstrips

Perry database after removing out-of-bounds and missing/abandonded airstrips

Add Spartanburg airports

Displaying Spartanburg airports along with the results from previous steps allowed me to see where the two databases overlap, and where the Spartanburg database can contribute to the Perry database within the previously established boundary.  From the screenshot below, it is clear a number Spartanburg airports/airstrips can be used to fill in the western corner of the Perry boundary.  As an unintended benefit of the default icon used in the Excel-to-KML conversion process, it is also easy to see where a Spartanburg database entry matches up with a Perry database entry.

Spartanburg airports added to the mix

Spartanburg airports added to the mix

Unfortunately for the home team, the Spartanburg database files don’t include a .CSV version, so moving Spartanburg airports into the modified Perry .CSV file wasn’t as straightforward as I would have liked.  The modified Perry .CSV file uses decimal degrees for latitude and longitude, and most of the other file formats use some variant of D:M:S – bummer :-(.  Oh, wait!  there is a .MXF version that *does* use decimal degrees – yay! (anyone know what nav system uses a .MXF file?).  OK, so using the .MXF file from Spartanburg in conjunction with GE, I can copy Spartanburg airport info into my modified Perry CSV file, and the review the results in GE after going through yet another Excel-to-KML conversion.  This was a bit tedious, as the .MXF format doesn’t include elevation or ICAO data.  So, I got the lat/lon from the MXF, and the elevation and ICAO code from the STX file – wonderful :-).

After slogging through the Spartanburg database, I wound up adding 22 airports, and the Perry count is back up to 192.  The Perry database with the Spartanburg airports added (all with the default icons) is shown in the following image.

Perry database after adding Spartanburg Airports

Perry database after adding Spartanburg Airports

Correct waypoint displacements as necessary

Looking back at the waypoint review in Part I, there are several waypoints where the waypoint symbol is significantly displaced from the actual geographic feature.  A 1 mile displacement doesn’t sound like much, but it can be a real problem if a pilot is low and under pressure, especially for airstrips like Holt (see below) where the airstrip location isn’t obvious.  Knowing that the symbol on their nav display is precisely located can mean the difference between being able to concentrate on getting away, vs a panicked search for a place to land.

Waypoint symbol is about 1 mi east of actual airstrip

Waypoint symbol is about 1 mi east of actual airstrip

So, the task here is to identify which waypoint symbols are displaced from the corresponding geographical features (already done in Part I), and adjust the waypoint symbol coordinates to move them appropriately.  Again I’ll use GE and my modified Perry .CSV file, as this allows me to rapidly check the result in GE by running it through the Excel-to-KML converter.

From Part I, the following waypoint symbol locations were corrected to line up with the actual geographic features

  • #10 Caraways Airstrip
  • #26 Judge Wil – note that the symbol displacement isn’t particularly relevant for this waypont, as the runway is no longer there, but…
  • #42 Wexford Mills
  • #43 Williston
  • Eliot Barrow
  • Green Pond
  • Holt
  • Sexton
  • Williamsport

After making the modifications to the .CSV file, I ran it through the Excel-to-KML converter and reviewed them all in GE. The following screenshot shows the ‘before’ (red) and ‘after’ (turquoise) symbol placements for #10 Caraways.

Caraways airstrip showing the 'before' (red) and 'after' (turquoise) symbols

Caraways airstrip showing the ‘before’ (red) and ‘after’ (turquoise) symbols

 

OK, so that’s it. I’ve sliced, diced, folded, spindled, and mutilated the current Perry database. The only things left to do are to work with John Leibacher to get it published on the Worldwide Soaring Turnpoint Exchange, and to generate my own personal database that has ‘problematic’ (read – too narrow/short for my 18m wondership) airstrips removed.

Publish the result as the ‘Perrry14a’ database

The ‘final’ CSV version was sent off to John Leibarcher a few minutes ago, for his review and processing.  Hopefully I’ll have the complete ‘Perry14a’ file set to play with in the next day or so (knowing, John, it will probably be in my in-box by the time I finish typing this!).  The next step is to re-review everything to make sure I haven’t screwed up too badly, and then to produce my personal ’18 meter friendly’ version of the NDB (for my SN10) and STX (for my ClearNav) files.

 

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