wmartin@stl-06sima.army.mil (Will Martin) (08/16/89)
This was on Risks -- thought it was worth getting into Telecom: >Date: Tue, 15 Aug 89 08:17:31 -0400 >From: dave davis <davis@community-chest.mitre.org> >Subject: Cellular Telephone Causes Airliner Fire Alarm A morning radio news report here in Washington, DC reported that a commercial airline crew noted a fire alarm signal from a cargo hold in mid-flight. Upon returning to their originating airport, the cargo hold was examined carefully, and no evidence of fire was found. Apparently, a cellular telephone in a passenger's luggage had received an incoming call, that activated the smoke (I assume) detector via RF interference. This occurrence shows why we have systems engineers. That is, someone who must consider not only electromagnetic compatibility between system components, but also with other systems in the same operating environment. As a result of this event, the aircraft companies may have to redesign a lot of sensors. Dave Davis, MITRE Corp., McLean, VA ----- End of forwarded messages
dave@uunet.uu.net (Dave Levenson) (08/19/89)
In article <telecom-v09i0303m10@vector.dallas.tx.us>, wmartin@stl-06sima.army. mil (Will Martin) writes: > This was on Risks -- thought it was worth getting into Telecom: > > >Date: Tue, 15 Aug 89 08:17:31 -0400 > >From: dave davis <davis@community-chest.mitre.org> > >Subject: Cellular Telephone Causes Airliner Fire Alarm > > A morning radio news report here in Washington, DC reported that a commercial > airline crew noted a fire alarm signal from a cargo hold in mid-flight. Upon > returning to their originating airport, the cargo hold was examined carefully > and no evidence of fire was found. Apparently, a cellular telephone in a > passenger's luggage had received an incoming call, that activated the smoke > (I assume) detector via RF interference. > ...As a result of this > event, the aircraft companies may have to redesign a lot of sensors. No. The only sensor that has to be implemented is the one that scans the passenger baggage. It is ILLEGAL to use electronic devices such as cellular telephones or even Walkman-sized portable receivers on board commercial aircraft. It is also ILLEGAL to operate such devices on other aircraft unless the pilot of the aircraft has determined that the device in question does not interfere with the aircraft systems. This part of the federal aviation regulations is chiefly aimed at reducing the risk of interference with the navigation or communications systems, in the interest of flight safety. While interference with the file alarm system may have been unexpected, the passenger who carried a powered-up portable electronic device aboard that aircraft is in violation of the law. What will probably result from this incident is not a major re-design of aircraft systems, but better enforcement of the existing regulations. -- Dave Levenson Voice: (201) 647 0900 Westmark, Inc. Internet: dave@westmark.uu.net Warren, NJ, USA UUCP: {uunet | rutgers | att}!westmark!dave [The Man in the Mooney] AT&T Mail: !westmark!dave
ron@ron.rutgers.edu (Ron Natalie) (08/22/89)
I'm skeptical about this article. The plane must have been on the ground or else it wouldn't be answering the phone call. Second, airplane control systems are already required to have RF immunity especially with the new all electronic control systems the FAA is increasing the protection that is required. -Ron
jjs@ihlpz.att.com (James J Sowa) (08/23/89)
In article <telecom-v09i0315m10@vector.dallas.tx.us> ron@ron.rutgers.edu (Ron Natalie) writes: >I'm skeptical about this article. The plane must have been on the ground or >else it wouldn't be answering the phone call. >-Ron Cellular phones don't have to be on the ground to answer a page message and start alerting. RF is able to travel vertical and horizonal. That is one of the reasons people were able to use cellular phones on commercial airline flights until they were banned by the FAA. "JUST DO IT!" Jim Sowa att!cbnewsc!jjjs Yep this is my on opinion and all that stuff must people add here.
j_prigot@uunet.uu.net (Jonathan M. Prigot) (08/25/89)
In article <telecom-v09i0318m08@vector.dallas.tx.us>, jjs@ihlpz.att.com (James J Sowa) writes: > Cellular phones don't have to be on the ground to answer a page message and > start alerting. RF is able to travel vertical and horizonal. That is one of > the reasons people were able to use cellular phones on commercial airline > flights until they were banned by the FAA. Does anyone know the differences that make use of private cellular phones "dangerous" and the use of public cellular phones on planes "safe"? -- Jonathan M. Prigot Telephone: 617-861-6600 x2148 W. R. Grace & Co. UUCP: j_prigot@wrgrac1.UUCP 55 Hayden Avenue (...!wang!wrgrac1!j_prigot) Lexington, MA 02173 1989 Poster child
Kenneth_R_Jongsma@cup.portal.com (08/28/89)
With regard to the question about why it is ok to use the public phones on an airplane and not your own cellular phone: The reason is that the public phones on airplanes are not cellular. There are multiple receiving stations on the ground, but I don't believe they do handoffs. In any case, that is beside the point. Whenever an electronic device is installed in an aircraft, extensive testing is done to make sure it does not interfere with any other device on the plane. Antenna location is critical, as is shielding. By using an unshielded transmitter in a "random" location, you open yourself up to interfering with all sorts of equipment critical to the safe operation of an aircraft. Even the thought of some guy whipping out his phone on the taxi in to the gate bothers me to no end. With traffic on the taxiways as busy as an expressway rush hour, I don't want anything to interfere with the flight crews communication with ground control or attention to detail. ken@cup.portal.com
OLE@csli.stanford.edu (Ole J. Jacobsen) (08/28/89)
There are two reasons why you shouldn't use your cellular phone in an airplane. First, the airlines are parnanoid about any electrical device which "can cause interference to avionic systems" and while their fear may be largely unfounded, they have little or no sense of humor about it. I even know of an airline in the UK which forbids the use of Walkmans for the same reason. (Yes, it is pretty bogus). Secondly, the FCC does not allow the use of cellular phones in a *flying* airplane, because it may cause massive interference to the cellular system. Remember that the premise of cellular is the control of intereference through many low-powered cells and high frequency re-use. Imagine what happens when you are up in a plane above a densely populated area: all of a sudden your phone "sees" many cell sites at the same time (and the cell cites "see" it). This can result in all sorts of crosstalk and interference. Don't do it. Ole
john@apple.com (John Higdon) (08/29/89)
In article <telecom-v09i0328m06@vector.dallas.tx.us>, wrgrac1!j_prigot@ uunet.uu.net (Jonathan M. Prigot) writes: > Does anyone know the differences that make use of private cellular phones > "dangerous" and the use of public cellular phones on planes "safe"? The use of cellular phones is not permitted from *any* aircraft. Not only for aviation safety reasons, but because of the havoc it wreaks with the cellular systems themselves. If a mobile comes up on multiple sites, the system will probably lock it out permanently to protect itself. The phone you are probably refering to is called "Airphone". It uses special equipment on a special frequency (950MHz band) and has special approval by the FAA and FCC for aircraft to ground communication. The phone in your hand is an ordinary *cordless* phone. The actual air to ground communications is performed by a transceiver mounted elsewhere on the aircraft. -- John Higdon | P. O. Box 7648 | +1 408 723 1395 john@zygot.uucp | San Jose, CA 95150 | M o o !
covert@covert.enet.dec.com (John R. Covert 28-Aug-1989 2106) (08/29/89)
>Does anyone know the differences that make use of private cellular phones >"dangerous" and the use of public cellular phones on planes "safe"? FAA regulations prohibit the use of all electronic devices not explicitly certified to be safe. Radio receivers and transmitters emit electromagnetic waves at frequencies that may interfere with an aircraft's communications or navigation equipment. The "Airphone" public phones aboard aircraft are specifically designed and tested to ensure that they will not interfere with the aircraft. FCC regulations prohibit the use of cellular phones aboard aircraft for a totally different reason: There are only 832 channels allocated for cellular service. In order to allow more than 832 calls to be active in a system, the channels will be reused only a few miles apart. The more customers a system has, the more cell sites it will have (and cell sites will be found in low, rather than high, places), the smaller the coverage area will be for each cell, and the lower the power your cellular phone will be told to use (by the cell site). This allows frequency reuse. If you are at 10,000 feet, your signal is going to reach not only the nearest cell site, but also several other cell sites using the same frequency. You will interfere with other calls. "Airphone" uses a separate group of frequencies. /john
mlr@houtz.att.com (Michael L Robins) (08/31/89)
Although there has been much discussion about cellular and Airphone radio
services aboard airplanes, early propagation work in Chicago revelaed that the
radio pattern for cellular is kind of a mushroom shape, and at the height of
airplanes >10,000 feet, I suspect that you would never be able to receive a
signal from a cell site. This was even true on top of the Sears Tower in
Chicago, and although a cell cite was easily in view, and about 3 blocks away,
it was about 4 hundred feet below, and we found that we were never even able
to talk to that cell site because of the shape of the radio signal. We found
that we were always talking to a cell site much further away. An example is
below:
/ airplane
o--/----/
ant \
________ | ________ \
/ \ | / \
/ | \ | / \
/ car| \ | / \
/ O---O \ | / \
Notice that when the plane is in the air that it is above the node of the
signal while the car on the ground works just fine.jad@dayton.dhdsc.mn.org (J. Deters) (08/31/89)
In article <telecom-v09i0330m02@vector.dallas.tx.us> OLE@csli.stanford.edu (Ole J. Jacobsen) writes: >First, the airlines are parnanoid about any electrical device which "can cause >interference to avionic systems" and while their fear may be largely >unfounded, they have little or no sense of humor about it. I even know of an >airline in the UK which forbids the use of Walkmans for the same reason. >(Yes, it is pretty bogus). I remember reading the sheet that came with my Sony Discman that came with the standard FCC disclaimer of "WARNING: This equipment radiates and uses RF energy..." It's just a CPU that's grinding out the tunes in there, and it's capable of emitting RF just like any other digital device. Taking off over a freeway with someone's poorly maintained automobile ignition is like flying over a spark-gap transmitter. Many frequencies with multiple harmonics, and more powerful than most C.B.'s. If they are as overly sensitive to stray RF as their paranoia indicates, I sure don't want to fly their airline! -j J. Deters - jad@dayton.DHDSC.MN.ORG john@jaded.DHDSC.MN.ORG
rusty@uunet.uu.net (Rusty H. Hodge) (09/01/89)
In article <telecom-v09i0315m10@vector.dallas.tx.us>, ron@ron.rutgers.edu (Ron Natalie) writes: > I'm skeptical about this article. The plane must have > been on the ground or else it wouldn't be answering the > phone call. Oh really? Radio waves don't travel up? :-> Although Cell Site antennas put the majority of their energy out in a pancake fashion, there is plenty of reflected signal. Have you ever listened to an FM radio while flying at 30,000 feet? You can hear stations from all over. -- Rusty "No Bugs" Hodge, 1588 N. Batavia St. Orange, CA 92667 Tel (714) 974-6300 rusty@hodge.cts.com [uunet zardoz crash]!hodge!rusty FAX (714) 921-8038