A little home experiment to demonstrate the effect of Cell phones on signal lines.
Take you old fashioned analogue land line and make a phone call. Switch on your Cell Phone and hold it say, 0.5m form the phone. Every time the Cell Phone sends out a signal to handshake with the base station, you can hear a a serious of short pulses on the land line. It works on Analogue lines, but I have noticed the effect on a digital land line. As a side note to put the risk of interfering with aircraft navigation systems into perspective. Some of our goods are fabricated form welded steel frames, and posses a residual magnetic field. So we have to follow the IATA Dangerous good regs to ship these things by air. The absolute limit for air transportation is a magnetic field strength of less than 5.25mG. The Earths magnetic field is 450 to 550mG. Don House wrote: > I have alsways thought this... however there is a man serving a year prison > sentence in England for interfering with a planes navigation system. There > is also a plane crash now attributed to a man who refused to stop using his > cell phone. This is out of my area but one of my fellow engineers says it > has to do with antenna placement on the aircraft. > > Don > > -----Original Message----- > From: [email protected] [mailto:[email protected]] > Sent: Thursday, January 25, 2001 9:26 AM > To: [email protected] > Subject: RE: consumer electronics used on board aircraft > > I may regret saying this, but isn't it conceivable that the FCC Rules that > make it illegal to use a cell phone in the air has more to do with the right > of the airline to sell expensive phone time, than the technical issues? :( > > -----Original Message----- > From: Brent DeWitt [mailto:[email protected]] > Sent: Thursday, January 25, 2001 10:08 AM > To: Mike Hopkins; 'Colgan, Chris'; 'Emc-Pstc' (E-mail) > Subject: RE: consumer electronics used on board aircraft > > My background is the pretty much the same as Mike's, which is probably why I > agree with his response. I just wanted to add that the prohibition on cell > phone usage (in the US at least) is not FAA or airline driven, but mandated > by the FCC. The architecture of the cellular system is rather carefully > planned. The placement of antenna sites, coverage and hand-off algorithms > are based on the propagation from land based phones, which is quite > different from a phone in an airliner 25000' feet up. The FCC has therefore > made it illegal to operate a cell phone after the wheels of the plane leave > the ground. > > Regards, > > Brent DeWitt > > "Takeoffs are optional. Landings are mandatory" > > -----Original Message----- > From: [email protected] [mailto:[email protected]]On Behalf > Of Mike Hopkins > Sent: Wednesday, January 24, 2001 11:38 AM > To: 'Colgan, Chris'; 'Emc-Pstc' (E-mail) > Subject: RE: consumer electronics used on board aircraft > > As a frequent flyer and private pilot with some knowledge of EMC, I'll throw > in a few comments: > > It is clear to me that consumer electronics can interfere with aircraft > electronics, and I've probably heard all the same horror stories -- DC10 > finds itself off course on landing, false engine warnings, interrupted > communications, etc... It isn't clear to me how prevalent this problem is or > if it happens often enough to be considered a problem. One instance of > electronic interference is enough to have everyone up in arms against the > use of ANY electronics in ANY airplane. > > On a 747 flight to the Pacific, I'd bet there are as many as 30 to 40 lap > top computers operating together at some point during the flight. > Additionally, there are probably another 40 to 50 walkman tape players or CD > players in operation, plus the on-board entertainment systems and a few > in-flight telephones being used. On shorter flights, there may still be a > large number of laptops being used by business people plus tape/CD players > and air phones and the like in use during the flight. I don't think this is > a general problems for aircraft electronics. > > HOWEVER; if radio or television receivers or cell phones were allowed, I > believe the level of interference could easily reach the level of being at > least disruptive to aircraft systems if not downright dangerous. I have > personally seen commercial scanners and FM broadcast receivers that will > interfere with voice comms -- 118MHz to 136MHz -- which means they could > certainly interfere with nav equipment operating between 108MHz and 118MHz > (VOR's and ILS's, specifically). I also have a Garmin hand held GPS system > that I cannot find anything that it will interfere with nor have I found > anything that interferes with it (except things getting in the way of the > antenna - Maybe I'm just lucky?). > > My sense is the following: Interference with nav stuff is the most likely -- > a VOR indicator off, or something like that. With GPS back-up (or getting to > be primary) in most aircraft, a faulty Nav indication would likely be caught > before it was a problem (NOT so if you're on an ILS approach in IMC > (Instrument meteorological conditions) where a faulty indication can run you > into terrain -- this is why no electronics should be operated on the > aircraft below 10,000 feet on take-off or approach). > > I doubt a cell phone caused the Saab to crash -- most airplanes will still > fly even with all electronics blocked out (don't know if the Saab is fly by > wire or not, but I don't think so). Horizontal situation indicators and > gyro's are driven by vacuum and in larger airplanes, there's back-up vacuum, > red flashlights in the cockpit, etc... Upsetting autopilot controls might > cause the airplane to do something erratic, but that sort of thing should be > recoverable as long as someone in the cockpit is paying attention. > > Enough of that -- need to get back to my real job.... > > Mike Hopkins > KeyTek > > -----Original Message----- > From: Colgan, Chris [mailto:[email protected]] > Sent: Wednesday, January 24, 2001 6:15 AM > To: 'Emc-Pstc' (E-mail) > Subject: consumer electronics used on board aircraft > > There is growing concern amongst professional aircrew about the use of > consumer electronics (CD players, mobile phones, hand held GPS etc) on board > aircraft. Some claim that passenger electronics has definitely interfered > with navigation systems, primary flight displays or engine warning systems. > There are rumours that a mobile phone contributed to the demise of a > Crossair Saab 340 on 10 Jan 2000 killing all passengers and crew. Some > pilots reckon that it is absolute nonsense. > > Knowing what you do, about how EM disturbance can affect electronics > equipment, that it is almost impossible to make electronics equipment > completely immune to EM effects, that FCC class B or CE marked equipment has > not been tested (presumably) with avionics in mind etc, etc, how do you feel > when the guy next to you on your flight gets his Minidisc player or laptop > out? Remember, when you are descending through a cloud layer, the pilot is > relying solely on electronics receiving equipment to get the aircraft on the > runway. > > Do you think all consumer electronics should be banned from aircraft, that > FCC or CE equipment is okay or that the whole issue is scaremongering > piffle. > > Any comments gratefully received, I will post a summary on a professional > pilots forum and let you know that results. > > Regards > > Chris Colgan > Compliance Engineer > TAG McLaren Audio Ltd > The Summit, Latham Road > Huntingdon, Cambs, PE29 6ZU > *Tel: +44 (0)1480 415 627 > *Fax: +44 (0)1480 52159 > * Mailto:[email protected] > * http://www.tagmclarenaudio.com > > ************************************************************** > Please visit us at www.tagmclarenaudio.com > ************************************************************** > > The contents of this E-mail are confidential and for the exclusive > use of the intended recipient. If you receive this E-mail in error, > please delete it from your system immediately and notify us either > by E-mail, telephone or fax. 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