Pablo's Mission Planning Website

Home Links Tips Downloads MPSSF Tips

Greetings Mission Planners,

Well The Mission Planning Users Conference is just one week away and it looks like the place will be packed.  Registration has been cut off, but you have until March 8th to arrange attendee substitutions or cancel out.  After March 8th you won't be able to get a refund for your attendance fee.  According to the MPUC website alternative lodging will be arranged for folks who don't yet have room arrangements.    

RUMINT from the new NGA Headquarters search...

For those who are interested in SRTM DTED (and who isn't?) you'll be glad to know that there's going to be an SRTM Workshop in Reston Virginia from June 14th thru 16th at the USGS Headquarters.  

Not too much more Mission Planning news I can speak of.  I suspect everyone else is saving up their news for next week.

Mission Planning Tip - Vertical Obstructions Part 3, VO Database

Part 1 of this series discussed the process of plotting obstructions on paper charts and part 2 discussed updating that data using the Chart Update Manual (CHUM) process.  Now it's time to consider how that data gets to, and is maintained by NGA.

Over the last several years the size of NGA's CHUM database has grown dramatically.  While they're not distributed on paper anymore, the Acrobat version of the CHUM books has grown from two to three volumes.  The number of EChum items has grown at the same rate.  In most cases the obstructions were reported by various Government agencies.  NGA has gotten quite good at mining data from the FAA, FCC and similar agencies in other nations.  Unfortunately this cooperation doesn't extend to all nations.  If you start from Seoul and pan your map north you'll note a dramatic drop in CHUM when you pass 38N.  Are there fewer obstructions in North Korea?  I don't know personally, but remember that one man's vertical obstruction is another man's (Kim Jong Il) airspace denial measure.  

Why doesn't NGA gather a worldwide database of towers using their own sensors?  Unfortunately finding towers is hard work.  Most things that intel traditionally looks for (planes, tanks, armies in the field etc) cover a large area and look unique.  When you look straight down a tower is pretty tough to see - and it's even tougher to be sure exactly how tall it is.  

That's where you come in.  While it's tough for NGA's VOD team to see towers (they work in windowless offices in St. Louis) it's tough for you to avoid seeing them when you're flying low.  The normal reaction when you nearly hit an unplotted tower is "#@?&+^ NGA!  When are they going to start plotting these towers?"  After the exercise is over you return home, forget about the towers and repeat the cycle a year later.  The reality is NGA isn't going to plot the towers until you tell them where they are.  All you have to do is send and email to chum@nga.mil and they'll add your tower to their database as a "reported" obstacle.  Once they know there's a tower in the area NGA will refine it's location and height using other sensors and databases.  

How can you send the data to NGA?  They'll take any data you've got in any format, but the more information you can enter the better.  Knowing there's a tower at location X is nice, but if you can provide estimated MSL/AGL elevations and tower type that will help.  If you create a Manual CHUM file in FalconView you'll get all the needed information.  You can send in your Manual CHUM file or using the latest versions of Excel2FV you'll be able to export your CHUM data to a spreadsheet, which they'd like even better...

As these new towers come in NGA adds them to the Digital Vertical Obstruction File (DVOF).  Unlike CHUM, DVOF includes all the towers NGA knows about. That list includes towers that already appear on paper charts, towers that are in the CHUM and towers that aren't tall enough to meet minimum chart plotting requirements.  The CHUM for a given chart is a subset of DVOF.  A tower is included in CHUM if it meets the minimum obstruction height for a chart (150ft JOG, 200ft for TPC and ONC) and it's been added/deleted or changed since the chart was published.

Of course there's a lot of people who want all the towers.  Just this week I was asked:

Is it possible to get the All of the vertical obstruction CHUM information in a format that F-View can read (so that even obstructions that are "burned in" can be highlighted like ECHUM and Manual CHUM is?

The good news is that the answer is YES.  The bad news is that there's a big but that follows...

If you go to NGA's SIPRNET home page you'll find links to NGA's products arranged in alphabetical groupings.  If you click on the range that includes "D" you'll be able to go to NGA's DVOF website and download in a range of formats.  Most of the formats are tabular text files imported by software in the same way PFPS imports DAFIF, but you're also able to download DVOF as a ShapeFile - which can be displayed in FalconView.  Unfortunately FalconView can only plot the data as a series of lines (powerlines) and points (obstructions).  They won't look like towers or EChum.  When you download the data from SIPRNET it gets all that classified stink on it, so it can't be transferred to an unclassified PC.  Some of the data in the SIPRNET DVOF file is classified (can't tell you which part), but NGA also can produce an unclassified version.  According to the ECHUM FAQ:

This information may be obtained from the Digital Vertical Obstruction File (DVOF). You may contact Ms. Kelly Stohl by phone at (314) 260-5066 or DSN490-5066 or email stohlk@nga.mil.  He will ask you for your area of interest, and will send you the most current and complete data.

If you take a look at the FalconView Overlay menu you'll notice one menu choice is grayed out:

Although "Vertical Obstructions" appears in the menu the choice is disabled.  The Vertical Obstructions Overlay turns on/off all known towers on any map or image.  Unfortunately it doesn't quite work, and that's why it's grayed out.  In 1998 NIMA produced a VPF Vertical Obstruction Database (VVOD) prototype CD.  The Air National Guard (thank you Mike Bartgis!) funded a FalconView VVOD overlay, but when the prototype wasn't followed by VVOD production the effort was curtailed.  The decision was made to continue to display "Vertical Obstructions" in the overlay list as a reminder of how important this feature was.  Over the next several years the Services continued to raise this as a high priority to NIMA and then to NGA.  Last year NGA agreed to restart the VVOD effort and produced an new unclassified prototype covering Nevada:

Through some sleight of hand (and registry editing) it was possible to display the data using FalconView's Vertical Obstructions overlay.  Although the data worked, the shortfalls in FalconView were apparent:

  1. VVOD towers plot on obstruction centerpoint as shown above.  Just like CHUM towers, VVOD towers should put their "dot" on the obstruction centerpoint.
  2. Unable to display obstruction heights.  VVOD towers should display their heights in MSL and AGL just like CHUM towers.
  3. Unable to manage VVOD using the Map Data Manager (MDM).  Should be able to use the MDM with VVOD just as you can with other VPF data like VMap and DNC.
  4. Need to manually edit the registry for each VVOD library.  FalconView needs to work with any VVOD files.

Although these changes may seem relatively minor, neither FalconView 3.3.1 or 4.0 have been modified to display VVOD.  Hopefully this will be changing soon since a plug in can be added to FalconView 4.0 to enable VVOD and fix the problems listed above.  There's also a lot of enhancements that are needed - for example displaying individual towers can lead to an unbelievably cluttered display.  You need software that automatically replaces groups of towers with the "multiple towers" symbol when necessary.  Once you've got a database of towers you can also take the next step and automatically calculate Minimum Safe Altitude (MSA) and Emergency Safe Altitude (ESA).

Paul