[Tfug] cell phones, bluetooth and airplanes (another question)

[Richard Rohrdanz]

On 8/15/06, Christopher Robbins <robbinsc at gmail.com> wrote:
>
>
> > As a pilot, private not commercial, I have also been concerned with
> > electronic interference affecting the instruments in my plane. I have
> used
> > my GPS (Bluetooth), my PDA and a cell phone with no problems in flight.
> > Some
> > of the cheaper electronics may not adhere to published and accepted
> > standards as well as they should and could cause problems. Some months
> ago
> > I
> > visited a web site (sorry, I don't have the URL now) that carried pilot
> > reports of interference on airlines from electronic devices in the
> cabin.
> > In
> > a couple of cases flight attendants discovered the violators (using
> > GameBoys), had them turn off the devices and the interference
>
>
> Could shielding the avionics prevent this type of interference? When I
> first
> read about Boeing's wifi technology (still digging), they had talked about
> protecting the instrumentation by some sort of shielding...With the
> instruments being obviously critical, why the hell isn't this standard on
> most planes?
>
> (Should have stuck around EE :) )
>
> -Chris
>
>
> --
> Chris Robbins
> Dept. of English Technical Support
> http://www.homerengineeringcorp.net
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>
Sounds easy enough and it is certainly the first thing one would think of
but... (here comes the FAA to help us) you can't make any permanent
modifications to an airplane without getting the FAA to approve of it.
Airworthiness is their mantra. Theoretically, you can't put in a single
screw into a piece of sheetmetal without getting an OK from the FAA. At
least that is what applies to normal airplanes. If you own an experimental
(AKA a kit airplane that was built by the pilot) the rules are much more
relaxed. I know one guy who has interfaced his Windows laptop with all the
flight control systems on his experimental plane. By the time he recovers
from a computer crash he may have already experienced a plane crash.
Actually he does have some backup instruments.

The second problem with shielding the avionics is that it is a massive job
in a small plane. Space and weight are paramount considerations in aircraft
and the smaller the plane the more important those items are. As a result
all the instrumentation is packed very densely in the area below the
windscreen and above the pilot's knees. By the time all the dials and
controls are installed the area looks a plate of multi-colored spaghetti.
Retrofitting the planes would be exceedingly expensive and time consuming.

Most of the planes in service today, commercial and private, are at least 30
years old. They were designed before there was such a thing as cell phones,
PDAs, GPSs, GameBoys and laptops. I'm afraid that the cheapest solution to
the problem of interference with aircraft navigation in the older planes is
probably through designing better electronic devices for passengers to use
in flight. For planes that are now on the drawing boards, we will probably
find better shielding will appear.


-- 
Richard Rohrdanz
(520) 743-7013
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