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[Shop-talk] Compressed Air Lines, RapidAir

Subject: [Shop-talk] Compressed Air Lines, RapidAir
From: jdinnis at gmail.com (John Innis)
Date: Fri, 14 Oct 2011 08:07:31 -0500
References: <alpine.BSF.2.00.1108032008290.9767@itonami.pair.com> <alpine.BSF.2.00.1110122353080.7629@itonami.pair.com> <BAY167-W1041F13DC93BC52303B82249FE00@phx.gbl> <4E9721DE.6050106@xxiii.com> <4E974B44.5050301@gmail.com> <alpine.BSF.2.00.1110131940490.27558@itonami.pair.com>
I work for a company that designs and builds the computers and displays that
pilots use to fly aircraft.  I can tell you that they have been two
confirmed incidents of a PED (personal electronic device) causing
interference with these systems.  One was a CD player with no wireless
capability at all (just a really noisy local oscillator in exactly the wrong
frequency range), the other was a laptop PC with an operating wireless
card.  The problem is that all electronic devices produce RF noise.  Most of
the consumer grade stuff is so poorly made that while the prototype MIGHT
have passed FCC testing, the actual units that people buy are often out of
compliance in terms of the amount of noise the produce.  A lot of the
computer systems used to keep airplanes in the air are hardened against this
noise as best we can, but we still depend on being able to receive good RF
signal from GPS, VOR, ILS, and a host of other systems that allow the plane
to navigate and communicate.  Until we get serious about testing consumer
products for noise radiation, it is a good idea to ban them from airliners.
Just because it has only happen twice, doesn't mean that the next time won't
involve a life threatening situation for someone you love.



On Thu, Oct 13, 2011 at 6:47 PM, David Hillman <hillman at 
planet-torque.com>wrote:

> On Thu, 13 Oct 2011, Scott wrote:
>
>> I dunno, I won't use pvc for air anymore.  I have, however, flown 250,000
>> miles (at least) having forgotten my phone was powered up in my backpack,
>> and the plane has never so much as hiccuped.  I tend to be skeptical that a
>> $200 million flying radio is going to be equipped with anything that has any
>> issues with a phone's cellular radio.  I mean, most planes in the U.S. are
>> rarely more than 40,000 feet off the ground, and most of the flights I take
>> are at about 20,000 feet.  That's four miles.  My phone easily has a range
>> of four miles, which means all those phones on the ground are emitting
>> something that could interfere with the plane too.  The cell phone frenzy is
>> one of those things that will convince us that we were retarded in 30 years.
>>
>
>   It just so happens that the company I work for puts cellular modems on
> commercial airliners.  It's how we deliver broadband internet to passengers.
>  We have over 2000 planes flying around the country every day, squawking
> back and forth to the ground via standard cellular technology. We have been
> doing so for 3 years.
>
>   The prohibition against cell use on planes is for passenger comfort, and
> security, not technical reasons.  Largely the same reason we can't provide
> VOIP on commercial lines, but we can on private planes, and they can in
> Europe.
>
> --
>  David Hillman
>
> PS You'd be surprised how often commercial jets crack 40k, but it's
> irrelevant.  We get hundreds of miles of range from our antennas.
>
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