Why cell phones are still grounded

Why the U.S. government wants the ban

Cell phones and other electronics vary in how much they could interfere with avionics. If it's determined that some devices do cause problems, all gadgets would have to do extra certification testing, which the government doesn't want to spend the money to do. The ban is cheaper.

Also: No FCC or FAA chairman wants to sign off a change in the rules because if a cell phone does cause either an aeroplane crash or a cell tower computer system crash, they don't want to be blamed. Keeping the ban is the safe decision for the politically ambitious. The ban is easier.

What are the facts?

DVD players, laptops, portable game machines, CD players, MP3 players all radiate energy, and theoretically could cause interferences with GPS systems, communications equipment and the aeroplane's interaction with distant navigational systems.

U.S. airlines alone carry on average some 2 million passengers per day. If just 1 percent of these passengers accidentally or deliberately leaves their cell phones on, that means some 20,000 cell phones remain on during flights every single day. Despite this, no crash has ever been definitively attributed to cell phone or gadget interference.

Many headsets used by private pilots come with jacks for using them with cell phones. The manufacturers say they're for use on the ground only. But many private pilots use them in the air without incident.

Cell phones are used in aeroplanes every day, and no crash has ever been definitively attributed to cell phone or gadget interference.

The TV show MythBusters "busted" as a myth the conventional wisdom that phones interfere with avionics.

However, a Carnegie Mellon University study conducted some four years ago found that portable electronics interfere with aeroplane systems -- especially GPS -- even more than previously feared.

The Radio Technical Commission for Aeronautics (RTCA), a nonprofit corporation that advises the FAA, studying the effect of phones on avionics. The RTCA is also looking at technologies that would minimize any disruption, including the use of ultrawideband frequencies and extremely low-power cellular phone systems. They're predicting a definitive answer to all this, but don't hold your breath.

Just this week, the FCC officially dropped its inquiry into lifting an existing ban on using cell phones during commercial flights. The FCC said after the ruling that "given the lack of technical information in the record upon which we may base a decision, we have determined at this time that this proceeding should be terminated."

So the ban remains in place because the government can't seem to come up with definitive answers.

But does that even matter? Interference problems could be overcome with well-understood techniques of shielding, reprogramming and other technology designed to facilitate safe calls.