Re: [amsat-bb] Airline Carryon

[Bruce Bostwick <lihan161051@xxxxxxxxxxxxx>]

> 1. A flight computer should not malfunction from interference on a VOR 
> channel.
I have to admit, I wouldn't think RF would cause flight computers to 
malfunction.  I definitely wouldn't expect LO leakage from even the 
cheapest FM radio to cause that kind of malfunction.  With interfering 
signals generated inside the aircraft in the range of several watts, 
possibly on harmonics of a parasitic resonance inside the cabling or 
equipment, it starts getting iffy.

> 2. No one should have entertainment equipment on during take off or 
> landing.
But they will .. out of any 100 or so people, you're guaranteed to get 
at least a few.

> 3. Aircraft antennas should be located in RF secure ares of the plane 
> and not near the passenger cabin. Cables running in the cabin should 
> be shielded in solid tubes or use fibre optics.
This would make sense .. but ..

> 4. FAA personel should have a extensive background in R.F. and 
> Avionics if they are in an inspection position of Avonics equipment.
(hysterical laughter)  You realize we're talking about the government 
here.

> 5. If the FM radio is properly shielded, and properly certified it 
> should not cause interference.
That's a given, but remember most PED's are made in China or similar 
places and barely function to begin with.  A $4.99 walkman-type FM 
receiver .. well, you get what you pay for.  Yes, they leak, lots worse 
than any HT you'll ever own, and on inconvenient frequencies.

> 6.Which side the L.O. is on is realy no part of my original discussion.
Maybe, maybe not .. there are a LOT of variables to consider.

> 7. This only happens when computer code is not debugged, FM radios 
> were not certified, personel are ignorant,  passengers do not follow 
> the flight rules, and flight attendents do not enforce the rules.
I agree that the flight computers and other avionics are way too 
sensitive to RF, even that generated by cellphones.  I also feel it's 
not realistic to expect 100% compliance from airline passengers in not 
using electronic devices on the aircraft, especially given the 
haphazard way the regulations are enforced and the fact that all too 
often flight attendants TRY to enforce rules and flight crews don't 
back them up.  It happens.

Personally, I feel it would be reasonable to have shielding on the 
avionics and cabling inside the aircraft sufficient to keep RF 
generated inside the cabin from getting into the system (although using 
a cellphone on board an aircraft screws up the cellphone system even 
more than it does avionics on board the airplane, and quite honestly, 
the FCC should be paying closer attention to that .. imho .. that's 
another discussion) and it would certainly help if the aircraft had 
some means of monitoring for interfering RF signals generated inside 
the cabin and alerting the flight crew.  All of that would make sense.

But then again, that word "should" says it all .. I'm sure the airlines 
would be able to come up with dozens of reasons why all of those 
technical solutions would be "impractical to implement".  And since 
most of the decision makers *don't* have a lot of technical savvy, 
that's enough to keep them from pushing the airlines to do any of those 
things ..

and we are WAY, WAY offtopic, needless to say ..

Heard from a flight instructor:
"The only dumb question is the one you DID NOT ask, resulting in my 
going out and having to identify your bits and pieces in the midst of 
torn and twisted metal."
----
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