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Comment by phkahler | Hacker News Reader

>> I guarantee this is the mistake they made.

No. East-West runways are very common.

If I may speculate... the blanking of 5 displays is probably not a bug. Maybe it's a (misguided) feature meant to keep people from landing at certain restricted airports and they coded the logic incorrectly?

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My guess is that it's not just any old "Runway 27", but it's runways where the coordinates of the endpoints of the runways have precisely the same latitude down to whatever precision is in the database. It's probably quite rare to have a runway that's this perfectly east-west.

Looking at the coordinates of the runways in the FAA database, they are all perfectly east/west within about 2 feet of deviation N/S. This would round to zero if the calculations were done as lat/long as single precision numbers.

Are there other runways that are so dead-on?

Runway 27 just means a runway that runs east-west and you're approaching from the west. Landing the other way it would be Runway 9, it's a neat little system that gives pilots everywhere a surprising amount of information in a single name.

I doubt even the military would want the risk of a humongous plane landing blind on their runway, no matter how many secrets they had nearby.

That's why I said misguided in parenthesis. I have no idea what criteria or scenarios it may have been for, but a commercial airliner could conceivably have an emergency almost anywhere and potentially be cleared to land at the forbidden locations.

Just speculation on my part but clearing all displays seems like deliberate behavior being incorrectly triggered.

> the blanking of 5 displays is probably not a bug

If it’s not in the manual, it’s a bug.

Most likely, but manuals have bugs too like typos and missing information.

Then that is also a bug.

Unless the argument you’re making is “two bugs make a bug intended behaviour”

  > Unless the argument you’re making is “two bugs make
  > a bug intended behaviour”

When you start finding so many bugs, it's time to start closing Windows.

I don't disagree, but I think it sort of illustrates the fact that using the term "bug" for documentation mistakes is a bit too non-standard, even though I used it myself.

Why are you so sure the blanking is not caused by a bug? “On error clear screen” seems like a pretty good way of making it very clear to the pilot that something has gone wrong and they need to fall back to manual procedures (rather than looking at displays that may have gone stale or be showing bad information).

I don't know a single airplane that does that and I've flown quite a few types.

It's normal to have error detection and the way to show it is to cross out (red lines, black background) the failed information on the screen. Not blank the whole thing.

The units are fairly independent in a modern system, communicating via data buses. So this sounds like a case where the bug made a unit emit something really bad on that bus to make them all go blank.

Ah, that makes sense. Thanks for the detail!

I had this fleeting thought as well but, the list of affected airports are all very benign. There's nothing of note in Wayne County, OH.

This can't be the case -- the bug only affects specific runways at these airports, not all the runways.

I have to assume then that these are the runways that lead down into the secret Illuminati bases beneath the airports. Has somebody taken a closer look?

NOTAMs are safer, cheaper, and more effective for this purpose than blanking aircraft instrument displays without explanation.

And if you have an emergency you’re going to put the bird down wherever there is a runway, even if it’s area51. You may be asked to call the phone number when you land tho :/

Exactly. The bug doesn't prevent landing, just shuts down some automation: effective ways to prevent landings include missiles, not obscure bugs.

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