I just finished a three-day business trip to Boston, once again using the very friendly Norwood Memorial Airport (the Wikipedia article needs some TLC) to the south of the city. Boston has a nasty airport security zone with high security fees, required prop locks, etc. Norwood is far enough to be outside the zone, but is near stations on two MBTA commuter lines, making it easy to get in and out of downtown.
When I’m flying, I usually leave my cell phone turned on (a grey area, I know) so that I can get access quickly in case of emergencies. During this trip, however, I noticed something strange: once I was in the U.S., I had either no signal or an extremely weak one with no bars. This continued all the way into Boston, even over cities and Boston suburbs. Coverage was great as soon as I was on the ground, so it wasn’t a problem with roaming.
I think that the cell phone company who partners with Bell Mobility (Sprint?) must be refitting their towers to block out signals coming from above. I’d guess that this is the first step to allowing cell phone calls from airliners, before setting up satlink cells inside the planes themselves. This change is significant for pilots like me, who hope to be able to use the cell phone for last-ditch emergency communication if all else fails. As an historical footnote, this change would also would have prevented the passengers of United Airlines Flight 93 from finding out about the WTC and Pentagon attacks and deciding to fight back against the highjackers. That said, the change is probably inevitable for simple business reasons.
Almost the second I flew across the St. Lawrence River from New York State into the province of Ontario, all of the bars on my cell phone lit up again.