Article 38063 of sci.geo.satellite-nav: Path: matra.meer.net!news.neumedia.net!uunet!in3.uu.net!206.154.70.8!news.webspan.net!feed1.news.erols.com!newsfeeds.sol.net!news.pagesat.net!news.he.net!news.iquest.net!not-for-mail From: "Edward J. Janeczek" Newsgroups: sci.geo.satellite-nav Subject: DOD Intentionally jamming GPS! Date: 13 May 1997 13:15:39 GMT Organization: R. O. Whitesell and Associates Lines: 38 Message-ID: <01bc5f9f$903d3360$LocalHost@ej-tecra> NNTP-Posting-Host: ind-0013-24.iquest.net X-Newsreader: Microsoft Internet News 4.70.1155 Xref: matra.meer.net sci.geo.satellite-nav:38063 I used my 12XL on a commercial flight to Las Vegas with an external Lowe antenna, and connected to my notebook and SA4. I sought permission from the pilot to use this gear, and he was happy to grant me permission, and even gave me a list of the waypoints on the flight path. He also gave me a copy of an advisory which stated, in part, that GPS signals within a 200-300 mile radius of certain location in the US would be intentionally jammed by the DOD. Here is an exerpt of the advisory: "The locations identified to date include, Utah, Arizona, California, SW Oregon, Southern Idaho, Western Colorado/Wyoming, Western Texas, New Mexico, Florida, and the central east coast." "Because of this, in the interim, dispatch will not be giving FRD (Fix-radial-distance) flight plans to crews transitting any of these areas anywhere near any of the time periods. You will receive airway flight plans only. Also, direct legs that ATC may issue that require the use of GPS is not recommended and should not be accepted. As more information becomes available we will re-evaluate the situation and advise you of any changes." "Below are the location/date/times that we have been initially notified of. If you encounter any problems or have questions regarding this, please direct them to your fleet manager or the manager of dispatch." "LOCATION DATE EFFECTIVE TIMES 300 NM radius ORL VOR 02 APR-25 APR 0300-0800Z 300 NM radius BVL VOR 23 APR-27 APR 0600-1000Z 300 NM radius TCS VOR 09 APR-31 JUL 0600-1000Z 300 NM radius NID VOR 05 MAY- 08 MAY 1600-1900Z 300 NM radius PDZ VOR 12 MAY-30 JUL 0700-0900Z MON/WED/FRI 200 NM radius PXT VOR 09 APR- 30 JUL 0400-0800 Z WED ONLY 300 NM radius TPH VOR 09 APR-13 JUN 0700-1200Z." I found this interesting, and I am curious as to why the DOD would perform intentional jamming. This, apparently, is in addition to SA. Any ideas out there?