Re: GPS tracking device allowed in commercial flights?

From: Alan Browne (alan.browne_at_FreeLunchVideotron.ca)
Date: 08/17/04 

Date: Tue, 17 Aug 2004 16:45:18 -0400

Meindert Sprang wrote:
> "Alan Browne" <alan.browne@FreeLunchVideotron.ca> wrote in message
> news:1voUc.85710$sk2.1721793@wagner.videotron.net...
>
>>The risk to interference in avionics is at many places, including
>>antennas. Given the large variety of aircraft configurations,
>>wiring runs and many unknowns, it has been deemed unsafe to
>>operate any kind of transmitter aboard an aircraft. Commercial
>>aircraft antennas range from fairly low frequency (ADF receivers)
>>to very high (weather radar in x-band). Some antennas have
>>filters at the mounting area, some do not but rely on in-chassis
>>filtering.
>
>
> Oh please! What about the aircraft's own transmitters? And now don't tell me
> their RF stays out of the cockpit...
> Every decent receiver (and you can count on aircraft stuff being decent) has
> all the proper filtering they need, effectively blocking 900,1800 or 1900
> MHz cellphone signals to a very low level.

Oh please! Consult RTCA DO-160D. It outlines how equipment on
board must not only be resistant to interference, but how it also
must not interfere with other equipment. Only emissions within
its band and via the appropriate RF port is allowed.

>
> Really, if aircraft electronics were so sensitive to RF interference, it
> would be impossible to have HF and VHF transmitters on board used for
> navigation and communication.
>
>
>>Your test is hardly exhaustive or conclusive. See RTCA DO-160D
>>for guidance.
>
>
> Sorry, don't have that at hand. My job only deals with EN/IEC61000-6-1
> and -6-3 and the likes.

Then you really have no place to make the comments you are
making. Commercial aviation requirements are very conservative
and tough. Recently, due to the advent of FADEC (which has no
radio receiver at all), the requirements to certify additional
electronics on board has become tougher.

>
>
>>When my cell phone (on, but not in use) is under my car radio
>>there are occasional bursts of modulation lasting 5 seconds or so
>>when the cell and phone conduct some back channel communication.
>
>
> You can hardly compare a car radio with a professional VHF radio.

That was in rebuttal to your previous statement (which you have
"conveniently" snipped out here) regarding an empirical test you
made (which is hardly applicable to airborne radios in the first
place).

Regardless, wiring errors can occur and remain in place aboard an
aircraft (Swisair 111 is an extreme example). Antennas provide
yet another means to get energy into places where it is not expected.

Again, see DO-160D and enjoy.

Cheers,
Alan 

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