AVmail: February 20, 2003

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Washington ADIZ

Why can't the FAA and DoD set up air corridors for safe passage into the three DC airports affected by the ADIZ?

Dave Rumney

GPS Jamming

Obviously, we need backup systems. With today's technology Loran-C can provide 2d navigation for enroute and terminal, and some non-precision approaches.

Local precision navigation can be provided by a self-organizing system of ground based signal sources, essentially another GPS constellation "orbiting" at 0 AGL. The transmiters would be identical and cheaply mass produced, perhaps sited on selected cell towers. ADS-B ground stations could piggyback this function.

With good forethought and cost-sensitive planning we can have a robust, accurate, affordable system.

Chuck Forsberg

AVweb responds ...

Thanks for writing. While your idea may have merit for some locations, I don't think it can replace space-based GPS for wide-area navigation. The problem is that ground stations are subject to range limitations due to the horizon, which affects low-altitude airplanes and, of course, all ground vehicles. I think that's why the military is working on the airborne "pseudolite" concept as a way to overcome jamming over a wider area -- and being based on an aircraft (manned or unmanned) will make it possible to deploy pseudolites anywhere they're needed. (Adobe Acrobat PDF on pseudolites available here.)

That said, dedicated ground stations might be a good idea for high-volume locations (core airports of Class-B airspace, etc.), and if it could be combined with ADS-B as you suggest, so much the better!

John Ruley
Author, GPS Jamming

Commercial Airline Fatalities

AVweb wrote:

Technology Aiding Pilots

While the FAA struggles with STARS, there's a steady stream of innovation helping pilots get the job done more safely and efficiently. A wake-turbulence detector and a collision-avoidance system for small aircraft are under development and a wind-shear detector has already been installed in New York, not far from where American Flight 587 last year crashed after a possible wake turbulence encounter.

I understand there were NO COMMERCIAL AIRLINE FATALITIES IN 2002. Did American FL 587 crash in 2002? And were there no fatalities?

Harry Bladow

AVweb responds ...

Good catch -- you are correct. American Airlines Flight 587 went down in Belle Harbor, N.Y., on November 12, 2001, not "last year." And sometimes I still write "2002" on my checks.

Kevin Lane-Cummings
Features Editor