Return-Path: Received: from pop3.olsusa.com ([63.150.212.2] verified) by logan.com (CommuniGate Pro SMTP 3.4.5) with ESMTP id 773005 for rob@logan.com; Thu, 03 May 2001 11:47:38 -0400 Received: from mail2.pe.net ([64.38.64.10]) by pop3.olsusa.com (Post.Office MTA v3.5.3 release 223 ID# 0-71175U5500L550S0V35) with ESMTP id com for ; Thu, 3 May 2001 11:40:44 -0400 Received: from ieee.org (IP-87-048.tem.pe.net [64.38.87.48]) by mail2.pe.net (8.11.3/8.11.3) with ESMTP id f43FlKT05365 for ; Thu, 3 May 2001 08:47:21 -0700 (PDT) Message-ID: <3AF17DB8.BDA2D2EC@ieee.org> Date: Thu, 03 May 2001 08:48:08 -0700 From: "Charles R. Patton" Reply-To: charles.r.patton@ieee.org Reply-To: lancair.list@olsusa.com MIME-Version: 1.0 To: lancair.list@olsusa.com Subject: Re: Wazzup with WAAS? References: Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Mailing-List: lancair.list@olsusa.com <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> << Lancair Builders' Mail List >> <<<<<<<<<<<<<<<<--->>>>>>>>>>>>>>>> >> One quick thought with regards to WAAS. I too wonder at the speed, or perhaps better, the lack thereof evidenced by the FAA. But I had the occasion the other day to be talking to a gentleman who makes GPS simulators. We got on the subject of WAAS. One important point germane to this discussion is the one of "satellite health." When the satellite transmits its coordinates, it includes a "health" bit that indicates whether the data is to be believed or not. There are known instances where the satellite said OK but in reality was not. If you were depending on GPS for an IFR fix, particularly during landing, this possibly would be a very bad, bad thing. Among other things, WAAS will be doing independent tests for the health of the satellites and independently transmitting confirmation of the health. So the idea is that if the satellite exhibits one of these rare failures, you still have a chance to reject the data and only use good data or abort before you get into trouble. Charles R. Patton N360JM >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> LML website: http://www.olsusa.com/Users/Mkaye/maillist.html LML Builders' Bookstore: http://www.buildersbooks.com/lancair Please send your photos and drawings to marvkaye@olsusa.com. >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>