Hi Keith,
I do understand Ing. Gert Gremmen's comments, but still wonder how the
airplane compass I mentioned earlier was interfered with by the
passenger's laptop.
I really can't say about any specific airplanes compass but I can help try
to understand what can cause such an effect. Compasses typically shouldn't
be affected by a laptop unless that laptop is in very close proximity to the
compass or the laptop has a large current draw. I've noticed the compass in
my plane swing when I engage the starter and after the motor is running it
indicates a slightly different heading then before engine starting. I've
used several laptops in my plane and have never noticed a change in compass
heading, it appears that the compass in my plane is not very susceptible to
such effects.
Of course compasses on large planes are typically remotely located
magnometers which feed information to cockpit displays such as horizontal
situation indicators, radars, moving map displays, air data computers,
sferics devices and so on. This data feed can be digital or analog but
typically its a databus like the ARINC 429. I doubt that the compass was
actually effected on this plane, most likely, it was the data link that was
causing problems (we can only speculate at this time). Since I now work on
radar systems and not airplanes, I feel confident that I am not overstating
the importance of my station in life by saying this is quite a serious
problem and should continue to be addressed to insure there is no loss of
life due to commercial electronics running within a transport category
aircraft. Remember, when operating in instrument meteorological conditions,
neither the pilots, or the autopilot knows which is up, down, north, east,
south, or west without the flight instruments, navigation receivers, and/or
the compass.
I believe your other points on EMC and safety are well stated. I've
downloaded your core document and hope to read it and get back to you with
any useful criticisms.
Edmund A Woodcox
Specialty Engineering
Electromagnetic Environmental Effects
=
LOCKHEED MARTIN
Naval Electronics Surveillance Systems-Syracuse
PO Box 4840
EP5-D5MD45
Syracuse, NY 13221-4840
===
Phone: 315-456-2650
Fax: 315-456-0509
Email: edmund.a.wood...@lmco.com
--
From: cherryclo...@aol.com[SMTP:cherryclo...@aol.com]
Reply To: cherryclo...@aol.com
Sent: Wednesday, January 02, 2002 11:24 AM
To: emc-p...@majordomo.ieee.org
Subject: re: EMC-related safety issues
I believe there are great problems with the use of the phrase 'spurious
emissions' in any context save that of a standard or law which defines
just what that phrase means.
I sincerely hope I am not one of those who is ever ready to overstate the
importance of their station in life ! But I do notice the following:
a) Very great commercial pressures to design very low-cost products in
very short timescales
b) A general lack of expertise in the relationship between EMI and safety
in commercial design and manufacturing companies
c) Great yawning gaps on EMC-related safety issues exist in both the
commercial EMC standards (almost all of which were not written with safety
issues in mind) and in the commercial safety standards (almost all of
which were not written with EMC in mind).
Since, as someone put it recently: We are now utterly dependant on
technology for all aspects of our life the above issues do cause me
to worry about the future.
Read my article EMC-related Functional Safety in ITEM UPDATE 2001 (pages
52-59) for more detail on my worries (www.rbitem.com) and see if you
agree. More senior EMC people than me share my concerns.
I am sure that all the safety engineers reading this will understand, as
many EMC and other engineers do not appear to, that just because nothing
bad has happened so far it doesn't guarantee that something bad will not
happen tomorrow.
I understand that under European Product Liability law (and I suspect in
US product liability law too) evidence of a historical lack of safety
problems is not considered sufficient proof that a design is as safe as
people generally have the right to expect.
I do understand Ing. Gert Gremmen's comments, but still wonder how the
airplane compass I mentioned earlier was interfered with by the
passenger's laptop.
Regards, Keith Armstrong
In a message dated 02/01/02 15:47:52 GMT Standard Time,
ken.ja...@emccompliance.com writes:
Subj:Re: EMC-related safety issues
Date:02/01/02 15:47:52 GMT Standard Time
From:ken.ja...@emccompliance.com (Ken Javor)
Sender: owner-emc-p...@majordomo.ieee.org
Reply-to: ken.ja...@emccompliance.com (Ken Javor)
To:cherryclo...@aol.com,
