# do cell phones work on airliners at cruise altitude? **URL:** \ **Category:** Factual Questions\ **Created:** [November 16, 2006, 4:25am UTC](https://boards.straightdope.com/t/do-cell-phones-work-on-airliners-at-cruise-altitude/380637 "2006-11-16T04:25:56Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![kencomer](https://avatars.discourse-cdn.com/v4/letter/k/85e7bf/32.png) [@kencomer](https://boards.straightdope.com/u/kencomer)\ **Post date:** [November 16, 2006, 4:25am UTC](https://boards.straightdope.com/t/do-cell-phones-work-on-airliners-at-cruise-altitude/380637/1 "2006-11-16T04:25:56Z")
In transcripts of flight 93 calls on September 11, one of the callers says that she heard from someone else on the plane that other planes had been hijacked. Presuming the plane was still at a cruising altitude (call it 32,000ft), would her cell phone still work well enough to carry on a conversation? What is the lowest altitude that–presuming one chose to ignore FAA/FCC laws against it–one could successfully use a cell phone while moving at around 500mph? (I’ve seen the answer according to A. K. Dewdney and am looking for independent verification.) ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [November 16, 2006, 5:08am UTC](https://boards.straightdope.com/t/do-cell-phones-work-on-airliners-at-cruise-altitude/380637/2 "2006-11-16T05:08:51Z")
I wouldn’t guarantee clear reception at that altitude, but yeah there’s a good chance the cell phone will work up there. Cell towers transmit with most of their energy going out parallel-ish to the ground. The antennas intentionally don’t send and receive well straight up, but they do go a fair distance if you go at a bit of an angle up from the tower. You can probably get spotty service over the entire altitude range that a commercial jet is capable of flying at. The closer you are to the ground the better reception your cell phone will get. ---
**Author:** ![Patty\_O\_Furniture](https://avatars.discourse-cdn.com/v4/letter/p/96bed5/32.png) [@Patty\_O\_Furniture](https://boards.straightdope.com/u/Patty_O_Furniture)\ **Post date:** [November 16, 2006, 5:14am UTC](https://boards.straightdope.com/t/do-cell-phones-work-on-airliners-at-cruise-altitude/380637/3 "2006-11-16T05:14:15Z")
[Is this the “answer” you’re referring to?](http://www.physics911.net/cellphoneflight93.htm) Science is good at helping us explain why things happen, but not always the best tool to use to assert why something can’t happen. I remember stories about how people refused to believe that AM broadcasts could be heard hundreds of miles from the transmitter. The discovery of skip zones suddenly made sense of it all. I’ve accidentally left my cell phone on a few times while on the USAir Shuttle from DC to LGA and in mid-flight I remembered to turn it off, but I noticed that I had one bar on the signal strength meter. I think it had switched to analog mode during the flight and I didn’t try to place a call but it seems as though it should be possible with that much signal. ---
**Author:** ![pilot141](https://avatars.discourse-cdn.com/v4/letter/p/e0b2c6/32.png) [@pilot141](https://boards.straightdope.com/u/pilot141)\ **Post date:** [November 16, 2006, 5:24am UTC](https://boards.straightdope.com/t/do-cell-phones-work-on-airliners-at-cruise-altitude/380637/4 "2006-11-16T05:24:43Z")
Just do the math - even at 33,000 feet you are barely over 6 miles up. Add in some angular distance and you are talking about 10 or 12 miles from cell phone towers. The biggest problem would be the rapid handing off from cell to cell and the chance of a dropped call. This only holds true in the densely populated eastern portion of the country where 93 flew. If they were over Montana the results might have been different. Also remember that before the financial debacle of 9/11 most airlines had “Airfones” installed. An American Airlines Flight Attendant on Flight 11 (the first to hit the WTC) called AA ops on an Airfone, and several passengers from United 93 used the phones as well to get in touch with family members. ---
**Author:** ![pilot141](https://avatars.discourse-cdn.com/v4/letter/p/e0b2c6/32.png) [@pilot141](https://boards.straightdope.com/u/pilot141)\ **Post date:** [November 16, 2006, 5:36am UTC](https://boards.straightdope.com/t/do-cell-phones-work-on-airliners-at-cruise-altitude/380637/5 "2006-11-16T05:36:54Z")
**Patty** I innocently clicked on your link. I want my 20 IQ points back. ---
**Author:** ![Declan](https://avatars.discourse-cdn.com/v4/letter/d/ecae2f/32.png) [@Declan](https://boards.straightdope.com/u/Declan)\ **Post date:** [November 16, 2006, 9:23am UTC](https://boards.straightdope.com/t/do-cell-phones-work-on-airliners-at-cruise-altitude/380637/6 "2006-11-16T09:23:51Z")
[QUOTE=kencomer] In transcripts of flight 93 calls on September 11, one of the callers says that she heard from someone else on the plane that other planes had been hijacked. Presuming the plane was still at a cruising altitude (call it 32,000ft), would her cell phone still work well enough to carry on a conversation? What is the lowest altitude that–presuming one chose to ignore FAA/FCC laws against it–one could successfully use a cell phone while moving at around 500mph? (I’ve seen the answer according to A. K. Dewdney and am looking for independent verification.) [/QUOTE] It would have to be a CDMA phone, as a GSM phone did not pick up any service signal back in September, when I turned mine on just to see. Declan ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [November 16, 2006, 11:19am UTC](https://boards.straightdope.com/t/do-cell-phones-work-on-airliners-at-cruise-altitude/380637/7 "2006-11-16T11:19:14Z")
[QUOTE=kencomer] In transcripts of flight 93 calls on September 11, one of the callers says that she heard from someone else on the plane that other planes had been hijacked. Presuming the plane was still at a cruising altitude (call it 32,000ft) [/QUOTE] If I recall correctly from the digging around done during the multitude of 9/11 threads on this forum, Flight 93 was not, in fact, at “cruise altitude” post-hijacking but much lower than such an airplane would ordinarily fly. ---
**Author:** ![PBear42](https://avatars.discourse-cdn.com/v4/letter/p/ecccb3/32.png) [@PBear42](https://boards.straightdope.com/u/PBear42)\ **Post date:** [November 16, 2006, 4:56pm UTC](https://boards.straightdope.com/t/do-cell-phones-work-on-airliners-at-cruise-altitude/380637/8 "2006-11-16T16:56:25Z")
Hey **kencomer** , welcome to the SDMB. Please understand that the 9/11 thing has been kicked around here a lot. IOW, you’re a bit late to the party but, hey, better late than never. Anyhoo, as for your specific question, see [here](http://911myths.com/html/mobiles_at_altitude.html) and [here](http://thewebfairy.com/killtown/chart.html#phone_calls).