Wednesday, June 06, 2007

Research Reading

I’m in the process of writing another lengthy article on the use of radar in air traffic control to avoid thunderstorms. We had a doozie here yesterday (thunderstorm that is.) It just popped up out of nowhere and we got about a half inch of rain in less than 30 minutes. It was much needed.

Anyway, this thought popped into my head -- some people might actually be interested in learning about various web sites to use for their own research. For example: You can see how badly Georgia needs rain here.

I don’t know if your state has information like this posted on the internet but I bet they do. It might not be obvious from that page that it’s run by the University of Georgia (look at the url and you’ll see “” buried in it.) Universities are always great places for information. And any state in which farming is a big industry will probably have something like it.

If you’re looking for thunderstorms (or any kind of weather information), the National Weather Service is a great place to start. The only problem you’re likely to have at this site is too much information. Let me help you narrow it down. To see the radar images, look on the left side column and click on “Radar” (big duh). It will give you a map of the United States. Just click on your state. For Georgia, you should now see this image.

That will do for a lot of folks but I want more information. First, I want to see the time-lapse loop. If you’ll look at the top of the left column you’ll see you have two choices. “Base” loop and “Composite” loop. I want the composite loop so click on that. If you don’t know the difference between “base” and “composite” and you can’t figure out why it matters to me, then you need to go to this site and do some reading.

”The main difference is composite reflectivity shows the highest dBZ (strongest reflected energy) at all elevation scans, not just the reflected energy at a single elevation scan...

The updraft, which feeds the thunderstorm with moist air, is strong enough to keep a large amount of water aloft. Once the updraft can no longer support the weight of suspended water then the rain intensity at the surface increases as the rain falls from the cloud.”

(emphasis added)

To over simplify it, the “base” image show’s you what is falling out of the sky. The “composite” image shows you what might fall out of the sky. Yesterday, that “large amount of water” included some pea-sized hail. Of course, if you’re in the sky, you might want to know what’s up there with you. That is the reason it’s important for aviators (and controllers) to make sure they’re using the composite image.

Things falling out of the sky is what inspired me to write the article I’m working on. Thunderstorms can make airplanes fall out of the sky. To find out about that subject, I go over to the National Transportation Safety Board’s (NTSB) aviation site. Specifically, I go to the “query” page.

As you can see on the site, they have all sorts of qualifiers to help you refine your search. It will take a lot of practice to learn to use the site well but I have to tell you, you’ll learn a lot just sorting through reports that you aren’t looking for.

But for me, in this instance, I knew a lot of the specifics. I knew I was looking for a Cessna 210 that crashed in Georgia and an Aerostar that crashed in Alabama within the last few years. Both of the accidents occurred at Atlanta Center when I was a safety representative for NATCA. I want to work on making sure that no one has to read anything like this again.

”The National Transportation Safety Board determines the probable cause(s) of this accident as follows:

The pilot's continued flight into known thunderstorms resulting in an in-flight break up. A factor in the accident was air traffic controller's failure to issue extreme weather radar echo intensity information displayed on the controller's radar to the pilot.

Don Brown
June 6, 2007

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