Category: Rant

When does a unit test become a system test?

In my part of the big project I’m on, I have a class called a Playlist, and a corresponding database table. Based on my analysis of how many Playlists are likely to be used in the lifetime of a system, I decided that an int would be more than adequate storage space for the sequential internal id number. Actually, a short would probably be adequate, but there isn’t any compelling reason to use shorts on modern systems since they don’t save much storage and they’re slower to process (is that true in Java? I know it is in C/C++.) And so I happily used this id all over the code.
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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.