Friday, March 13, 2009

It's in the Cards

I sat down with my instrument student and started point out the features on the enroute chart of our local area. He had just done a good job with the infamous Pattern B, and it was time to start to learn to navigate.

"Now, here at Pocatello they also show the localizer."

"Why's that?"

"Because it helps define TYHEE. If the localizer is part of the enroute structure they show it." I showed him the legend, which obscurely notes "ILS Localizer course with additional navigation function."

"I thought the localizer course was 211." Look closely: the chart says 208. The change was made about five years ago; the ILS chart has the correct bearing.

I have always been impressed with the way the chart makers work. There are so many details, and so many tiny decisions that can make a big difference in readability. Chart errors, in my experience, are rare. But here was a chart error.

The front of the NACO charts has a big box. "FOR CHARTING ERRORS CONTACT," giving snail mail and email addresses, plus a phone number. As much as I would have like to talk this over with somebody, and to hear their reaction, time has been very short this week and I sent an email.

"Maybe they'll give you a year's free subscription," my student suggested.

Alas, they did not. I got the following email.

So they had already fixed it. No, I don't know what Everest is (other than a mountain in the Himalayas).

My new enroute charts arrived on Wednesday (before the AIRAC date, this time) and I immediately tore open the package and dug out the L-11 chart. The localizer course was correct.

What I don't know is whether the incorrect localizer bearing was shown on only one edition of the chart or on many. I was impressed that they caught the error, though. Think of all of the frequencies, bearings, latitudes, longitudes, elevations, variations. airway names, runway lengths, and other data on these charts. While I am pretty sure that the chart publishers depend on local pilots to catch errors, in this case they caught it before the "local" guy did. Good job!

I still would like a year's free subscription, though...

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At March 16, 2009 at 9:49 AM , Anonymous John said...

Good reminder to cross-check your charts.


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