As Salon's Patrick Smith notes, "Few rules are more confounding to airline passengers than those regarding the use of cellphones and portable electronic devices." I'd add the quart-sized plastic bag to that list, but I digress: Smith is right. Is it really true that something as innocuous as a Treo left on in row 32 could cause a jumbo jet to go down in flames? Let's ask Smith himself: He isn't just a pundit, he's a commercial pilot as well.

Part of the issue regarding stowing electronics at takeoff and landing, says Smith, has nothing to do with the fabled "interference," but rather that they can be dangerous as impromptu projectiles in the event of a sudden stop. Just ask the lady who decided to leave her tray table down and a full cup of Coke on it during my recent return flight from Vegas. Amazingly, it didn't stay where she wanted it to.

That aside, what happens in the cockpit when you forget to shut your phone down during takeoff? Most likely: Nothing. But interference is possible. Smith doesn't use this analogy, but try putting your cell phone next to a cheap PC speaker and turn up the volume. You will probably note an occasional, rapid, syncopated beeping coming from the computer speaker. If you've ever heard this before and wondered what it was, now you know: That's interference between the two devices.

Now an airplane is considerably more complicated than a $10 speaker, so the stakes are much higher should interference occur. But as Smith notes, airplanes are also designed to take this kind of interference into account. Smith himself says that he's never noted anything on the flight deck that might have been caused by a cell phone, but how would he know. Airplanes exhibit brief, oddball glitches all the time, and usually no one ever knows what the source was. (All that aside, at least two major incidents, including one crash, have been blamed on cell phones, though neither has been proven.)

The airlines don't really seem to care too much about the cell phone rule: Smith estimates that about half of all cell phones are left on during flight. My personal experience observing other passengers validates this.

Smith wisely notes that one big reason for the cell phone rules is that the potential for danger of phones ensures that people won't demand to use them in flight. Most fliers, as we know, despise this idea, but serial chatters are far more, ahem, vocal about the issue. No one wants a war over technology at 35,000 feet. Those days, however, are already arriving in Europe, as onboard cellular systems have already been approved. Will the U.S. see the same? Smith feels it's inevitable, and he's probably right.

LINK: Are cellphones dangerous to flight?