can airline staff tell if you are using a radio transmitter on board?

[Aestivalis]

@Hail Ants

Here’s a quote from Capt. Meryl Getline, an airline pilot who writes a Q&A column in USAToday:

By the way, an auto-land is one of the reasons you shouldn’t use your cell phone or other electronic devices when they’re restricted onboard. These devices have been known to cause little “glitches” in the signals used to execute auto-landings in low visibility. A glitch will cause a warning due to a signal interruption, and when that happens it is mandatory for the pilot to scrub the landing and circle around for another attempt

Anecdotal report here. I was flying into O’Hare during a snowstorm in an Embraer Regional Jet, and the pilot aborted two landings before the flight attendant came stomping down the isle. The girl in front of me was listening to her CD player (so loud that I should have noticed) and the flight attendant snatched it out of her hands, turned it off, and gave it back.

We ended up landing in Milwaukee and taking a bus back to O’Hare. Joy!

[I_is_smart]

I fly privately fairly often and I’ve never had one of the pilots fuss at me or even mention the cell phone issue even though they know I have one and that I leave it on.

The biggest problem is that you rarely can get texts out or get a signal for calls. I once had to turn around right before landing due to an issue with the plane (if we landed on the short runway and the warning light was accurate we’d be unable to take back off). One of the pilots suggested that I try calling the people I was meeting. It didn’t work, but I tried.

If the pilots told me to turn it off, I would though.

[Musicat]

@Una Persson

IIRC the primary problem is that it would hand off too quickly, not that it can talk to multiple towers. Look at a cell phone tower map, and note that they often are in a triangular grid (sometimes shown as a hex grid). Most phones have the range to contact several towers at once when in use. How the towers decide which one you are “talking” to is something I am ignorant of, but I do know that you can be equidistant from more than two towers and still have the system work. Hopefully a cell phone expert can shed some light on why…

IANACellphone expert, but I know a little about them. They were designed so that a phone on the ground can contact one or just a few cells. Each contact occupies a channel on that tower, even if it is not the active one. One phone using up two or three channels total is part of the system, but a phone in a plane could use up hundreds of channels over hundreds of cels, and that is less tolerable. I’ve even heard of prohibitions against celphone use in high-rises for that reason.

[Xema]

@Musicat

One phone using up two or three channels total is part of the system, but a phone in a plane could use up hundreds of channels over hundreds of cels, and that is less tolerable.

This may apply to analog systems, but with digital systems and signals becoming the rule, in principle it should be rather easy to limit the problems associated with a phone being receivable at many cells.

I’ve even heard of prohibitions against celphone use in high-rises for that reason.

That’s a new one on me. And note that in hilly terrain you’d need a corresponding rule against using your phone at higher elevations. I suspect a cellphone outfit that tried to enforce such a restriction would get murdered in the marketplace.