Confession.  I once left my computer on during takeoff. I know I shouldn’t have. I really shouldn’t have. But it was acting up and half the time when I shut it down it wouldn’t turn back on again unless I plugged it in, so I left it on going through security in case the screeners wanted it turned on, and then I forgot, and… well, it’s not a very good excuse. And I really really will never do it again.

I’ve read enough to know that in a perfect world, with brand new planes and pristine mobile gizmos that have never been, oh, dropped on a sidewalk, turning on a computer, or even a phone, won’t cause problems for the pilot.

But I also know that this isn’t a perfect world, and there a heck of a lot of gizmos on a plane, and no one really knows how they all will interact, particularly with the wiring on older planes, and I don’t want to my gadget to be the one causing trouble. Since 2000, the New York Times reports, there have been at least 10 voluntary reports filed by pilots with the Aviation Safety Reporting System when devices used by passengers clearly were interfering with flight electronics (pilots test this when flight systems are behaving oddly by asking passengers to turn their gizmos on and off.)

Back in 1996, fellow Spectrum senior editor Linda Geppert and I reported on a study from the RCTA, a nonprofit that advises the FAA; the RCTA had looked at anecdotal reports of problems, but couldn’t quantify the real risk, and urged more research to be done.

In 2006, Bill Strauss and his coauthors from Carnegie Mellon University reported in Spectrum’s Unsafe At Any Airspeed, that, according to measurements made on 37 flights during 2003, least one person on a typical flight makes a cellphone call, and that cellphones and other portable electronic devices can indeed interfere with normal cockpit instruments, concluding that, eventually, a device like a cellphone will be found at fault in an accident.

This research hasn’t been repeated recently; but you have to think it’s happening more and more. Folks don’t like turning off their smart phones. Ever. And the so-called airplane mode doesn’t exactly solve the problem. On a recent flight I told the really large guy in a leather jacket crammed into the seat next to me, who was trying to make a cell phone call halfway through the flight, to please turn off his phone or put it into airplane mode. He told me he had tried airplane mode—but it wasn’t working, it wouldn’t let him make the call. And he’s probably not the only person confused.

But odds are his phone hadn’t been dropped, it was a fairly new plane, and everything was fine, as it usually is. Usually.