At 01:04 PM 3/21/01 -0800, Marshall T. Rose wrote:
IEEE Spectrum from about 3-4 years ago had a lot of information on this. I
don't have the issue here, but it's a starting place.
ole - thanks. my basic question remains the same, setting aside the
non-reproducible anecdotal reports, can anyone point to an actual scientific
study, i.e., a controlled experiment. i've yet to see one...
/mtr
Nothing to do with scientific studies, but...
First, here is FAR (Federal Aviation Regulation) 91.21:
(a) Except as provided in paragraph (b) of this section,
no person may operate, nor may any operator or pilot
in command of an aircraft allow the operation of, any
portable electronic device on any of the following U.S.-
registered civil aircraft:
(1) Aircraft operated by a holder of an air carrier
operating certificate or an operating certificate; or
(2) Any other aircraft while it is operated under IFR.
(b) Paragraph (a) of this section does not apply to--
(1) Portable voice recorders;
(2) Hearing aids;
(3) Heart pacemakers;
(4) Electric shavers; or
(5) Any other portable electronic device that the operator
of the aircraft has determined will not cause interference
with the navigation or communication system of the aircraft
on which it is to be used.
(c) In the case of an aircraft operated by a holder of an air carrier
operating certificate or an operating certificate, the determination
required by paragraph (b)(5) of this section shall be made by that
operator of the aircraft on which the particular device is to be used.
In the case of other aircraft, the determination may be made by the
pilot in command or other operator of the aircraft.
Effective Date Note: At 54 FR 34291, August 18, 1989, Sec. 91.21 was
revised effective August 18, 1990, as set out above.
Which, to the uninitiated, says that except for Portable voice recorders,
Hearing aids, Heart pacemakers and Electric shavers, it is not allowed
_unless_ the airline has determined that it can be done safely (i.e.
not interfering with navcom systems). So, the lack of a scientific study
(if any) is strong evidence that the airlines have not made such a
determination :-) There is probably also a hidden liability issue;
if airline X allows, say, laptops during landing and one of their planes
goes down, some lawyer can claim that X did not do adequate enough studies
to determine that things are safe, blah blah blah. Also, note the date
that the regulation went into effect... I suppose one could try to get the
FAA to change its mind, but the FAA is not known for moving quickly...
Second, ILS landing aids are radio systems that operate in the
frequency range 108.10MHz to 111.95 MHz (this is _not_ GPS -- it's highly
directional radio beacons set up at airports). This is fairly close to
some of the frequencies inside of laptop PCs, so it is not unreasonable
to believe that interference _could_ occur. Having watched pilots do
instrument approaches, you really don't want them worrying about the possibility
that the guy playing blackjack will put the red-9 on the black-10 and
cause his ILS receiver to hiccup while he's in the scuzz, 10kts above VS0
at 100'...
As to cell phones, there is another issue, one that I would have thought that
the engineering talent of the IETF would have spotted immediately -- think of
the handoffs as a 747 full of cellphones is zipping along at 600+ MPH...