Path: utzoo!telecom-request Date: Sat, 18 May 91 09:55:08 PDT From: "John R. Covert 18-May-1991 1018" Newsgroups: comp.dcom.telecom Subject: Re: Cellular Phone Use in Aircraft 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 367, Message 5 of 8 Lines: 76 >> Warning: Using a Cellular phone on an aircraft is a violation of federal >> law and probably some FAA regulations too. You risk getting arrested. > Yes -- but they don't *tell* you that anywhere, so I assume I'll get > at least one warning (before possible arrest) ... Ah, but they _do_ tell you. Every airline's in-flight magazine has a notice forbidding the use of any electronic devices, especially radios, on board aircraft. And besides, ignorance of the law is not a valid excuse (or so I've always heard). It was my understanding that the relevant FAA regulation (FAR 91.19) prohibits use on Instrument Flight Rules (IFR) flights only (virtually all commercial flights will be IFR) and that the prohibition applies from the point at which the aircraft begins moving under its own power until cancellation of the IFR flight plan (which happens automatically upon landing). When I first got my cellular phone, the commercial pilots I talked to told me that this was the case, and I always turn my phone off when I feel the aircraft being pushed back (even if this is not under the aircraft's own power). However, the FARs, being regulations, can be changed at any time, and you are required by law to abide by them. I'll try to get an actual copy of FAR 91.19 to see what it currently says. I know it talks about electronic devices potentially interfering with BOTH navigation and cockpit communication. A critical issue for ALL radios, including the RECEIVER inside a cellular phone, is what frequencies are used for the injection frequency and the intermediate frequency (IF) of the superheterodyne receiver. In my phone, a Nokia P-30 (equivalent to the Moderator's Radio Shack CT-301), the injection frequency in the first IF stage ranges from 785.88-810.81 MHz, resulting in an IF1 of 83.16 MHz. The second stage injects 82.705 MHz, resulting in an IF2 of 455 kHz. Other phones will be designed to use other frequencies, and any of these frequencies could interfere with equipment aboard the aircraft, not necessarily because of design problems with the equipment, but because these frequencies may actually be used for communications. Any superheterodyne receiver is also a transmitter. The radiated power will be very low, but if you're sitting right on top of the antenna of a device designed to receive at the IF frequencies of your receiver, you will interfere with the other device. I have heard at least two recent reports about airlines telling passengers not to use their phones on aircraft at the gate (the one in Telecom from Chris Schmandt and one from a friend sitting in an American Airlines aircraft at the gate in Dallas/Fort Worth last Thursday), so it is possible that FAR 91.19 has been amended to apply at all times aboard aircraft. I called four airlines: American told me that the rules apply at all times. TWA told me that it was between me and the captain. Delta told me that the rules applied at all times. Continental spent the most time researching it, and told me that it was Continental's interpretation of FAR 91.19 that no electronic devices except those specifically authorized by Continental's corporate headquarters may be used from the time you step over the threshhold of the aircraft until the time you leave the aircraft. The reason stated is that even while on the ground parked at the gate, the flight crew will be in communication, by radio, with the tower to make the flight arrangements. Electronic devices, of which cellular phones are only one, may interfere with cockpit communications. Even if FAR 91.19 doesn't specifically state that the prohibition applies on the ground, there is also a broadly worded FAR which prohibits any kind of "interfering with a flight crew". This regulation essentially requires you to do exactly what you are told, within reason, by any airline employee. Failure to obey the instructions of a flight crew member is a crime punishable by law. john