Re: McDonnel Douglas warns against carry-on electronic devices

From:         drchambe@tekig5.pen.tek.com (Dennis Chamberlin)
Organization: Tektronix, Inc., Beaverton,  OR.
Date:         17 Jan 93 17:57:57 PST
References:   1 2 3
Followups:    1 2
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In article <airliners.1993.49@ohare.Chicago.COM> driscoll@src.honeywell.com (Kevin Driscoll) writes:
>In article <airliners.1993.36@ohare.Chicago.COM> barr@ash.mmm.ucar.EDU (Keith Barr) writes:
>>
>>Wouldn't there be a change in attitude if the autopilot was engaged,
>>which it obviously was, and if the navigation equipment was disturbed by RF?
>
>In this case, it is
>possible (but highly improbable) that a CD player could effect the radio
>nav (which is forward and under the cockpit).

I guess I can't swallow the idea that a passenger's CD player is going to 
find its way into nav or other avionics gear. If the manufacturer really 
said this, I interpret it as straw-grasping in the absence of other 
explanations.

The most powerful components of a CD player are presumably the motor drive
and audio output. Not much there. I would think that if the aircraft systems
were so exquisitely sensitive and even if by some fault the system wiring
in the cabin area were effectively unshielded, the resulting problems would
be frequent to continuous, and emerge from many other sources than CD
players.

We all live in an environment of electrical noise from multitudes of man-made
and even natural sources. Some of these are of much greater magnitude than
anything that could be supplied by the batteries in the CD player. The 
normal operations of the aircraft itself emit electromagnetic energy of 
considerable power.  The cabin audio/video system is itself of much higher
power than the CD player, although the manufacturer does control its 
installation and engineering.

I am sure that during development and manufacture, an expensive set of quite
sensitive measurements establish the electromagnetic compatibility (EMC) of	the aircraft with itself and both known and arbitrary outside sources. I 
believe that if the various and powerful internal and external sources over
a broad band were ever to start talking to the sensitive systems, we are 
going to have much more to worry about than CD players.