Qantas and WA again

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As mentioned a few months back, something strange is going on with
Qantas planes and WA, and it's happening again:
http://www.news.com.au/perthnow/story/0,27574,24864822-2761,00.html
This is getting spooky.

Dave.

Re: Qantas and WA again

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If the HEH base is the cause, then them thar Airbussen must be particularly
sensitive.  All sorts of aircraft use Learmonth on a regular (and irregular)
basis without having these hiccups.

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What's the HEH base ? And have these incidents been in its vicinity ?

Graham



Re: Qantas and WA again
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A Yanky submarine comms base:
http://www.alternatezone.com/images/P7220512.JPG
http://www.globalsecurity.org/military/facility/exmouth.htm

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200km, near enough for the Authorities to at least consider it:
http://www.news.com.au/perthnow/story/0,21598,24650057-948,00.html

Dave.

Re: Qantas and WA again

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US NavComSta Harold E Holt.

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The latest incident was cited by ATSB's release
http://www.atsb.gov.au/newsroom/2009/release/2009_01.aspx
as 350NM S of Learmonth.  From memory that is about 40k south of HEH, so that's
about 690km as the crow flies from the plane to the antenna array.

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You mean the antenna's nowhere near the base ?

Graham



Re: Qantas and WA again
On Sat, 03 Jan 2009 04:20:45 +0000, Eeyore

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The antenna array is adjacent the base (at Exmouth), which is ~40km from
Learmonth.

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The Exmouth base transmits at Very Low Frequencies. Only an uneducated
or uninformed person would believe it could interfere with a planes
controls.


Re: Qantas and WA again

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Not necessarily the case.  Shielding of the electronics by the aircraft skin and
frame will be less effective at VLF frequencies, so while I am rather sceptical
that HEH is the trigger (more on the basis of distance and power levels) I would
never say never.

Besides, we also have to look at the "French factor".  Remember the air show
crash (different Airbus model) where the software decided to land when the pilot
clearly had other plans for his day?  Some say French logic is an oxymoron.

Re: Qantas and WA again

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It beggars belief that even the most poorly trained designer would leave an
aircraft's controls susceptible to radio fields when we have so many of
them, natural (eg lightning) and unnatural (such as the various facilities
discussed).  The news media will now utter the usual pseudo-science that
does so much harm -- eg 'lightning never strikes the same place twice' or
'magnets in blankets proven to cure rheumatism'!



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Does it? Modern management technique is to regard any employee as "hire
tools" and take the lowest price. It is exactly the scenario that can lead
to susceptible equipment.

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Aircraft regularly get struck by lightning but very few fall out of the
sky because of it. Not a plausible argument.

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1. How many fell out before they learnt to protect them?

2. Was this the usenet group that posted the link of the guy being flown
by helicopter to be deposited on hign tension power lines to bruh the cob
webs off or something? Applying your logic, people should be electrocuted
ether.

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So are modern aircraft protected or not?
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?

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Just a shame about the ones that do though. It's happened :-(

MrT.



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Radio waves have trouble getting through small gaps. A rule of thumb is
about a quarter of a wave length. That's why you can see into a
microwave oven, the mesh on the window is too small to allow the
microwaves out. It follows that shielding will work better at low
frequencies than high frequencies. I'm afraid I can't see the connection
between a air show and VLF radio waves.

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Not that I was referring to apertures, but ...

Apertures in an EM field act as antennae, and re-radiate energy from incident
fields accordingly.  So as their dimension in wavelengths diminishes so does
their re-radiating efficiency.  The "shielding effect" of apertures relates to
their size in wavelengths and this determines the extent of re-radiation vs
reflection.

But the 'skin depth' is proprtional to wavelength.  Longer wavelengths are less
screened by thin conductive sheet.  At VLF (like the 15kHz HEH used to use -
don't know what they are up to nowadays) the skin depth is likely a lot greater
than the actual airframe cladding thickness.

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It was a reference to Airbus software and French logic.  Whether the ADIRU
disconnect was caused by an equipment hiccup or by the software's imaginative
response to a sensor's signal remains to be determined.

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So you're saying VLF radio energy from the base snuck through a hole in
the fuselage somewhere and still had enough power to interfere with the
controls, and only has done it on one or two occasions despite the fact
that hundreds, if not thousands of planes, pass by that area each year?

Re: Qantas and WA again


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If there is digital logic involved, it may only have to change 1 bit.

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Correcto. The totally unknown factor is when the antenna array is actually
transmitting and at what power and, maybe, in what direction. We also do
not know the fault log on the installation. Some of their gear might be
EOLing with undesireable effects.

Also, can you assure me that Quantas recalled all those aircraft that
their fake engineer worked on and did all the work again? Or did they take
a business risk on it?

The problem is that, now matter how unlikely anyone thinks it is, it will
never be proven impossible.

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No, it didn't sneak "through a hole".  Get that hole idea out of your nut.

Yes if the electronics inside is susceptible to VLF energy, then who knows
whether enough could penetrate the skin (NOT holes) to cause an undesirable
result.

Thousands indeed do pass that way each year.  But as others have mentioned, who
knows when the Tx is actually transmitting?

And if you had bothered keeping up, you will notice where I indicated my view of
this:

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I remain of that view.  You can take whatever position you like.

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