On Wed, 12 Jul 1995, Paul Robichaux wrote:
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Ed Carp said:
This sounds like absolute propoganda. If you do the calculations, you'll see that a 1 watt transmitter sitting 100 feet away from your target will generate an EMF less than that 1000kW ERP TV transmitter array you just flew over. If aircraft avionics were *that* sensitive, we'd have planes falling out of the sky, and we don't.
Oh, yes-- we do. The Army lost a small number (two or three) of of UH-60 Black Hawks in crashes where the flight control system suddenly commanded extreme pitch or attitude changes. Why? In all the crash cases, EMI from nearby TV or FM transmitters was found to be the proximate cause. The Army, and Sikorsky, immediately went to work to better shield the FCS from EMI.
It's interesting to note that the Navy's SH-60, a UH-60 variant, was designed from the start to be EMI-immune. Ships' radars operate in the 10-100kW range, and that's a lot of EMI when you're landing 15-20m away from the radar mast.
Well, I was speaking of commercial aircraft, not military, but the point is taken. I haven't had occasion to use my packet radio lashup on a UH-60 -- yet ;) -- Ed Carp, N7EKG Ed.Carp@linux.org, ecarp@netcom.com 801/534-8857 voicemail 801/460-1883 digital pager Finger ecarp@netcom.com for PGP 2.5 public key an88744@anon.penet.fi Q. What's the trouble with writing an MS-DOS program to emulate Clinton? A. Figuring out what to do with the other 639K of memory.