2 comments on cell phones in the air

[Dave Farber <dave () farber net>]

-------- Original Message --------
Subject: Re: comment?
Date: Sun, 05 Mar 2006 16:44:52 -0800
From: Brad Templeton <btm () templetons com>
Organization: http://www.templetons.com/brad
To: Dave Farber <dave () farber net>
References: <440B80F6.3040507 () farber net>

On Sun, Mar 05, 2006 at 07:23:18PM -0500, Dave Farber wrote:
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> - -------- Original Message --------
> Subject: Re: [IP] more on Maybe the cause is bad desigb of aircraft cell
> phones and electronic devices are a risk to planes]]
> Date: Sun, 05 Mar 2006 16:08:19 -0800
> From: Glenn Fleishman <glenn () glennf com>
> To: dave () farber net
>
> Brad Templeton <btm () templetons com> wrote:
> > As was, I believe, noted in the study, every day large numbers of people fly
> > in planes forgetting to turn their cell phones off.  They don't make
> > calls but
> > the phones regularly look for towers and broadcast to them on cellular
> > frequencies.  High in the air they see several towers, on takeoff and
> > approach
> > they see fewer, but are closer.  Planes are not falling from the sky.
>
> Specious logic. The researchers have some hard data about the potential for
> increased risk because of the disparity between the tolerance of
> avionics and
> the allowed out-of-band emissions by consumer electronics. The
> researchers have
> data that shows that GPS receivers could be interferred with by the use
> of cell
> phones and potentially other equipment. Because GPS is increasingly
> relied on
> for landings and other purposes, but that increase has happened gradually,
> planes aren't yet falling out of the sky.
>
> I would rather concur with the researchers that the potential for
> interference
> is there based on their analysis of regulations and real cell phones
> emission
> patterns, and wonder whether more research should look into what happens
> when
> 100 to 300 cell phones are left on during a flight and dozens of people make
> calls to an on-board pico cell.
>
> I'm not sure why researchers that produced a very prudent paper showing
> real-world performance and raising real-world risks with very reasonable
> conclusions--including much more testing, including cockpit RF monitors--are
> being so highly criticized for suggesting there's a paucity of real data
> contrasted with their collection that shows a real risk.

Their research showed people were making calls, and phones were transmitting
various signals, including frequently during takeoff and landing.  Their
research did not uncover any actual reports of interference with a
commercial
flight, but did have one anecdote of a Samsung cell phone interfering with
the GPS in the cockpit of a small aircraft.

Their report was that the cell phone frequencies themselves would not be
a problem, but rather spurious radiation in other bands (which is limited
by regulation but still exists.)

I don't dispute this is possible.  What I stated was that since, as the
research points out, it is going on all the time -- and we are not seeing
incidents, this suggests it is not time to shut down all electronic
devices.  The researchers do point out that there are incidents with
inadequate reporting that might be due to interference by passenger
equipment, and want better testing to find out if that's true, and more
research.

There was a study a few years ago (talked about on Dave's list in fact)
which
showed interference.  It turned out they had taken a cell phone at full
3 watt
power and placed it right next to the cockpit equipment, as I recall.

So I don't think we need to rush to ban electronic equipment.
Commercial jet
GPSs use, I believe, and external antenna outside the metal body of the
aircraft
in any event.   But that doesn't mean I am against doing more study, and
doing
more work to isolate aircraft electronics from interference.   Truth is,
as noted,
that if they are that vulnerable to interference, we should be more
worried about
terrorists using that to bring down aircraft, either from the ground, or
from
the plane, or simply from the cargo hold, where it's easy to ship a powerful
radio transmitter without even boarding the plane.

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