It's About Time!

Finally someone comes out and tells the truth about cell phones and aircraft instrumentation...and it only took the airlines opening up Wi-Fi on flights to make someone actually do their research and explain it to the rest of the world. Cell signals do not interfere with aircraft communications or other instrumentation. The radio waves used by cell phones are limited to specific frequency bands shown here, and they do not overlap with those used by aircraft communications as seen in the U.S. Frequency Allocation Chart. They've traditionally been prohibited on board airplanes because they play havoc with the cell phone networks.

A cellular network works because the towers have overlapping areas of coverage -- think of a Venn-Diagram -- and when the phone is in the intersection of two towers' coverage areas, it chooses to use the one that gives it a better signal. The problem is that the radio waves used by cell phones get blocked by buildings, mountains, trees, and other unfortunate side-effects of civilization and geography so the towers are fairly close and powerful to provide good coverage. A plane flies over all the detritus on the ground and your cell phone can receive a decent signal from towers miles away. This means that the phone is constantly switching towers to find the best signal and that puts unwanted strain on the network. A cell phone will crash a plane the same way it will crash a car -- by distracting the driver, not by interfering with instrumentation. And airline pilots get slightly more training than automobile drivers.

Wired magazine ran an article in the current issue that mentions this, although it doesn't do much to explain it. The primary focus was to let people know that several major airlines are providing Wi-Fi service to passengers via-cellular networks. The way these work is by having a "cell tower" in the plane connect to the base stations and all the network devices on the plane connect to its tower instead of the cell sites, thus avoiding the network problems described above.

I may have some details wrong in the above description as I don't know a great deal about radio communications, but the gist is correct and this has been a pet peeve of mine for a long time, so I'm glad the myth is finally getting resolved. It's as bad as the 10% of your brain myth.

~KMarsh