On Jan 25, 8:15 am, "Marco Leon" wrote:
Saw a repeat episode of Mythbusters for the first time last night about
the use of cell phones on an airplane and interference with cockpit
instruments. I know that this was mentioned in a November 2006 thread
briefly but the short of it was that they concluded cell phones really
CAN interfere with the VOR signals.

Sometime in the last year or two, the IEEE (the main EE professional
society) had an authoritative article about this in their monthly
magazine "IEEE Spectrum." The bottom line as I remember it: 99.999% of
cell phones and other electronic gizmos cause absolutely no
interference to flight instruments. (The 99.999% figure is indicative,
not exact.) But, very rarely a cell phone or other electronic device
gets out of spec on RFI (but still "works" so far as the user is
concerned) and can make the FI's go haywire.

The authors conclude that unrestricted use of cell phones and other
electronic devices (including ones now allowed) will probably cause a
crash something like once every decade or so. I forget the number, but
it's in that ball park -- the kind of thing that, until it happens, the
regs seem overly restrictive. But after it happens, everyone will ask
"Why didn't they ban those devices?" If memory serves me, the authors
cannot rule out that such crashes have already happened.

The authors had done a study in which they planted a measuring device
in a suitcase and flew it on a large number of flights in an overhead
bin, and recorded the EM spectrum. Interestingly, they found cell
phones were used illegally about once per flight or thereabouts. They
also found a number of cases where a device had failed, at least in the
sense that its spectrum could cause interference to GPS and other FI's.
They also reported one incident where an airliner's FI's went haywire
and the captain asked everyone to shut down all electronic devices. The
FI's recovered, and a bit of sleuthing traced the problem to one
passenger's device.