Text 1429, 91 rader
Skriven 2007-05-10 08:46:22 av Roy Witt (1:397/22)
   Kommentar till text 1367 av Ward Dossche (2:292/854)
Ärende: Airbus
==============
09 May 07 10:18, Ward Dossche wrote to Roy Witt:


 RW>WD>> Several airlines here have already experimented with micro-cells
 RW>WD>> on board aircraft while aloft ... KLM was the firstone to
 RW>WD>> introduce it, Air France has done so as well.

 RW>> Yes, but those micro-cells aren't in the hands of the public. I
 RW>> suspect that it's a specially built, well shielded xter.

 WD> I think that was what was meant in the announcement of Emirates which
 WD> you refered to: using microcells. Working for a company which offers
 WD> cell-phone services I've tried switching on my mobile in-flight and
 WD> hardly ever got a signal while overhead land in Europe, even at
 WD> minimal altitudes.

No doubt. Cell site antennas have a footprint to serve those on or near
the ground, not those above 5000 feet.

 WD> It's not that I'm suggesting the airborne phonecalls of 9/11 couldn't
 WD> happen because a friend of mine who flies 747's had his cell-phone go
 WD> off at 30,000 feet over Madrid Spain after he forgot it in his
 WD> pilot-jacket. But just picking-up the phone at 30,000 ft doesn't mean
 WD> it would work without a glitch just like that.

Unless there was a cell site in orbit.

 WD> Heck, even while landing at JFK inbound from Brussels the last time a
 WD> flight attendant said I couldn't snap photos and, heaven forbid, even
 WD> videos. Not because of RF-issues with the camera (which contains an
 WD> oscilator) but because of anti-terrorism measures ... I failed to
 WD> understand which though.

The airlines claim possible RF interference with the aircraft's flight
instrumentation, probably when the cell phone is transmitting. You have to
remember that an aircraft fuselage acts like an RF cage. Do some research
on Michael Faraday's theory on RF cages, or shields. It goes way back to
the 17th century and still holds true today. I would put my trust in the
engineers who equip those airplanes, they probably know what they're
talking about much more than the layman.

 WD> So, did I comply? Just go to http://welcome.homedns.org and watch
 WD> jfk1.jpg and jfk2.jpg. The firstone is Block Island between Martha's
 WD> Vineyard and Long Island, the 2nd one is a Swiss A330 snapped during
 WD> braking on the runway.

Of course, if your cell phone were the cause of that aircraft to crash,
you wouldn't be here to tell the story.

 RW>> Actually, any spurious RF in an aircraft is not an alleged problem.
 RW>> It can be as real as a flight computer being jammed or worse. Just
 RW>> as an old CB radio in today's computerized cars can be a problem, it
 RW>> is more dangerous to an aircraft that is on it's own at 50k feet.

 WD> Having been in the industry research projects for possible negative
 WD> RF-effects of the European GSM-system I can only repeat that any of
 WD> the tests ever conducted, with and without assistance of airlines,
 WD> hospitals and operators of other conveniences always yielded a
 WD> negative result. Seemed perfectly safe.

I wouldn't argue with the requirements of the airlines, they know more
about their equipment than I do...and I certainly wouldn't want to be the
person who caused one to crash, especially if I were on board.

 WD> It is perfectly OK to use a GSM-phone in an aircraft while aloft.

Not according to the airline industry.

 RW>> Like I said above, I was talking about cell phones in the hands of
 RW>> the public.

 WD> That's what Emirates are also talking about ... GSM-phones in the
 WD> hands of the (flying) public and operated via on-board micro-cells.

Which would be shielded to prevent any interference. As would the
instruments the other airlines claim would have a problem with it.

 WD> The only operational problem discovered was the heat-generation of
 WD> such cells and the associated cooling-issues as well as hightened
 WD> fire-hazard.

I doubt that there's a problem with that. But if they're worried about it,
they could place the cell on the outer hull and the cooling problems go
away. Not to mention some of the RF interference they may experience with
the cell inside the hull.


                R\%/itt

--- Twit(t) Filter v2.1 (C) 2000
 * Origin: SATX Alamo Area Net * South * Texas, USA * (1:397/22)