Boiled down to its essence, the ongoing debate about whether cell phones and other personal electronic devices could ever pose a true risk to the safety of an airline flight by messing with the cockpit displays comes down to this: We still don't know.
Yes, a new study just published validates that airline cabins are full of radio energy emitted by cell phones, DVD players and portable GPS devices, but we already knew this.
While the recommendations of a research team at Carnegie Mellon University are largely right (we need more research and more money for the NASA reporting system in aviation; and we need to harmonize airborne emission standards and get the FAA and FCC to cooperate), there is still no definitive evidence that the electronic gadgets we can use in flight (though are not necessarily permitted to) can pose problems.
But here's the bottom line: People will cheat. Always.
They will make clandestine phone calls on the landing approach or run devices the flight attendants told them to shut off when the plane is cruising below 10,000 feet. Depend on it. In other words, if flight safety depends on compliance in the cabin with directives to turn off or not use certain devices, then we're already operating in an unsafe system, which I do not believe is the case.
When and if we ever do discover and validate that there is a true, no-foolin' potential for in-cabin passenger electronics to bobble or interfere with flight deck instruments, we have only two choices: completely ban devices like cell phones, DVD players, GPS units, radios -- or whatever items are found to be particularly dangerous, or beef up the invulnerability of the instruments in the cockpit so that radio interference is impossible.
The latter is the only rational solution, and achieving the status of an interference-free cockpit is already a known art.
The U.S. military has had decades of experience in "hardening" cockpit electronics so that powerful radio emissions from, for example, shipborne radars or enemy transmitters can't penetrate it.
We're talking about protecting against huge amounts of radio frequency power, and the fact that it can be done. In the case of an airliner, we're talking about a latticework of essentially tiny signals bouncing around inside the aluminum tube that is a fuselage.
Hardening any cockpit instruments that are confirmed to be vulnerable in the civilian airline fleet should be a lot easier and ultimately cheaper in monetary and political terms than trying to get passengers to check their valuable electronics at the door and risking an airline flight's safety if someone cheats.
The reality is that almost all cockpit electronics are well-shielded already.
If there are exceptions to this -- and the research team raises some worrisome examples of potential interference with global positioning satellite systems that are an increasingly important part of low-visibility instrument approaches -- then GPS receivers and antennas on the outside of the aircraft need to be better tested and better shielded.
If for some reason that's not possible, then and only then should we turn to the flying public and -- armed with hard and fast scientific certainty in place of anecdotal pilot stories of mysteriously twitching needles -- explain why certain emitters (personal electronics) simply can't fly again. Ever.