Re: Can't use GPS on Alaska Airlines

From:         Reid Fairburn <cr_king@cr_king.seanet.com>
Date:         13 Sep 96 03:03:33 
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Hello to all!

        There has been a lot of discussion about how electronic systems
being used in the cabin may interfere with airplane control and/or guidance.
I would like to affirm that it is a real problem that is currently being
investigated at the appropriate levels to determine the hard facts.

        There have been observed incidents of interference in at least 50
cases I would guess.  The effects have been 300 ft excursions up and down in
VNAV, noticeable lateral offsets in LNAV, saturated on-course guidance in
the ILS, and equipment disconnects for unknown reasons.  Many of the
incidents have been investigated by the pilots during flight where they
found that if the electrical device was turned off...the problem went away.
When it was turned on again...it came back.  I would call this a hard fact
observation.

        It does not happen predictably and seems to be associated with the
particular electronic device construction or operation...one might cause
problems and the next one doesn't.  Laptop computers, gameboys, and
telephones are the main sources suspected withs observed incidents involving
more gameboys and laptops.  Also, each airplane would seem to be a little
different in the degree of succeptability to the problem.

        The problem is being addressed, I think, by hardening the systems in
the airplane and trying to reduce emissions from the electronic devices and
I am sure you will hear more in the future.  Anyway, when you are told to
turn off the stuff in the cabin...do it!

Reid Fairburn
Creative Kingdom, Inc.
cr_king@cr_king.seanet.com
206-946-4815