Path: utzoo!telecom-request Date: Thu, 16 May 91 13:45:27 PDT From: Ted Marshall Newsgroups: comp.dcom.telecom Subject: Re: Cellular Phone Use in Aircraft ... It Worked For Me! Message-ID: Organization: TELECOM Digest Sender: Telecom@eecs.nwu.edu Approved: Telecom@eecs.nwu.edu X-Submissions-To: telecom@eecs.nwu.edu X-Administrivia-To: telecom-request@eecs.nwu.edu X-Telecom-Digest: Volume 11, Issue 365, Message 3 of 10 Lines: 43 I am wandering away from cellular and telecom in general, but I feel that someone needs to respond to this. Note: I am not an Airline pilot or in any way associated with an airline. However, I am a private pilot and am familiar with aeronautical radio navigation. In article , ronnie@sos.com (Ron Schnell) writes: > [...] The FM radio/Computer rules are generally airline policy. It is > pretty much accepted these days that these things can't really mess up > the navigation equipment. Most airliners now use longer range > navigation systems like LORAN or various satellite-based systems, > which can't be upset by FM interference. [...] This is just plain wrong! Loran-C and GPS (satellite) navigation are being used in air navigation, but, to my knowledge, mostly in smaller aircraft. GPS, in particular, cannot be used 24-hours/day because there are not yet enough satellites in place. Over-ocean operations do use other forms of navigation, including inertial navigation, but almost all domestic US enroute navigation is via VOR (VHF Omnidirectional Range). Also, bad weather approaches into all major and many minor airports are via ILS (Instrument Landing System). Both VOR and the lateral directional portion of the ILS use the frequency range 108-118 MHz. Note that this is right above the FM broadcast band. Now, say that you are on an airliner shooting an ILS approach with an ILS frequency of 110.1. If you have an FM receiver on board with an IF frequency of 10.7 MHz (very common) and you tune it to 99.4 MHz, it may well leak an RF signal at 110.1. That may not be strong enough to interfere, but if it is, I would not like to be in the next seat as the pilot shoots an approach in a 200-foot overcast and 1/2 mile visibility. Bottom line: don't assume that that FM broadcast band radio you brought on board won't cause problems. Maybe it won't, but you're betting many lives on that. Ted Marshall ted@airplane.sharebase.com ShareBase Corp., 14600 Winchester Blvd, Los Gatos, Ca 95030 (408)378-7000 The opinions expressed above are those of the poster and not his employer.