Category: Flying

Free aeronautical data

Because of the imminent death of DAFIF data, it is my intention to create a web site where people can create and edit aeronautical data, and use the data that they and others have created in their personal computers, PDAs and web sites for flight planning, navigation, flight simulation, or other uses. This data would be free in both senses of the word, both free from cost, and covered by a Creative Commons or similar license allowing them to use it and distribute it free from legal encumbrances.

My first thoughts on the design would be that it would import and export data in an XML format, probably an extension of GPX or possibly another custom format. I’d like to make the editing as interactive as possible, so I’m currently learning AJAX (Asyncronous Javascript And Xml) programming, and possibly I’d like to leverage the Google Maps API.

I haven’t decided on the back-end language, only that it must run on a Free operating system like Linux or one of the BSDs, and use an Open Source web server like Apache or Tomcat because that’s what my stuff is currently hosted on. But if a bunch of you say you’ll do programming work on the site only if it runs on .NET, I’d still want to be involved in the project, but you’ll have to find a different web host.

I’d like to get an idea of how many people out there would be interested in

  1. Participating in the design and construction of such a site
  2. Using such a site to enter or edit waypoints
  3. Use such data in programs or sites that they have

If you’re interested in participating in such a role, please comment on this post describing which you’d like to do. If the first, describe what sort of programming you’re interested in doing. If the second, describe what sort of data you would expect to enter – just one or two local airports, a whole state/province/country, or what?

If I get any interest, I’ll probably create a mailing list or wiki for this. In the meantime, I’m putting posts on this topic in a separate category which you can read here or you can RSS subscribe to here.

The Waypoint Generator is boned

It’s official – the National Geospatial Intelligence Agency (NGA) has decided to remove public access to the Digital Aeronautical Flight Information File (DAFIF). For more information about what DAFIF is, why it’s important, and why it’s being taken away from us, see this page.

I don’t think my waypoint generators will die, but they sure won’t be as useful for people outside of the United States as their data gets staler and staler.

This is a sad day for me.

Rules lawyers and old wives tales

The regulations concerning flying are dense, confusing, impenetrable, and where they aren’t self-contradictory they leave terms undefined and open to wrong interpretation. So it’s not too surprising that most pilots (and instructors) rely on a collection of old wives tales and wrong impressions, and that arguments are frequent and bloody on rec.aviation.ifr.

Last week, our flying club sponsored an FAA Safety Seminar on how to fly the new GPS systems. Our “rival” club Artisan just installed Garmin 530s on all their aircraft, and we’re all jealous as hell. So we got the guy who trained all of them on how to use the Garmins to give us a seminar on the basics. Now, he’s probably spent a lot more time studying the regulations than I have, but something he said looked just plain wrong to me.

The FAA has certain requirements that specify when you have to file an alternate airport, in case you can’t complete the instrument approach at your destination. It’s a bit of a stupid regulation, because in actual fact there is no regulation saying you have to actually divert to that airport if you decide you can’t make your destination, but I guess it serves the purpose of getting you to look at and think about alternatives in the area. In the GPS naviation world, the FAA recognizes that the reason you might not be able to complete the approach at your destination might be a GPS failure, either in your plane or in the system, which would mean that you can’t do a GPS approach at your alternative. So if you are required to file an alternate, that alternate must have at least one non-GPS approach that meets the criteria for being used as an alternate. (Not a big deal for me, since I always look for airports with ILS approaches for alternates.)

So far, that makes a lot of sense. You can see the reasons, and it adds redundancy and safety and eliminates single point of failure errors. But here’s the bit that looked dead wrong to me: He said that if you go to the alternate, you’re allowed to use the GPS approach if your GPS is working, but you’re not allowed to use the GPS to navigate the missed approach procedure if you have to “go missed” (abort the approach) there. I suspect he’s misinterpreting a rule that says you have to be able to navigate the missed approach procedure without GPS if your GPS fails.

I feel better about that decision

Friday I agonized over the weather decision. Today the TAF (Terminal Aerodrome Forecast) is calling for fairly strong gusty winds – nothing I haven’t dealt with before, but not conducive to passenger comfort – and the FA (Area Forecast) is mentioning widely scattered thunderstorms. The surface analysis map shows a not too wide or strong line of showers approaching, but a strong occluded front and a very low Low right behind it, so who knows what might be popping up during the day. So yeah, I probably wouldn’t have been happy with myself if I’d flown Vicki up here, knowing we’d be dealing with all that turbulence on the way home.

Yesterday and early this morning there was a lot of wind shear in the forecast – David Megginson comments on it (in context of Watertown’s forecast, which was similar to Rochester’s) over on his blog. It appears that whatever weather mechanism was making strong winds just above the ground yesterday is extending down to the ground today.