Cellphone signal received at 30k feet.

[Owen Lucas]

I forgot to to put my phone in airplane mode and realized this when I received a text message half way through a 2 hour flight.

I presume we were at 30k feet based on max altitude according to flightaware.com and under the assumption that the flight is at its highest point mid journey.

I attached photos below that I took (and sent) to my recipient at that height alerting them to the fact I received their message during my flight. One of the 2 photos and multiple texts went through. Maybe someone can verify the altitude from the photos.

A single bar would pop up every few minutes allowing me to carry on a conversation. I thought this was really weird but hey, I guess 4G towers have some distance to them? Is there any other reason why I would get a signal so high up and not throughout the flight? Improperly aimed call antenna?

p.s. I was not connected to onboard Wi-Fi.

 

[atikovi]

And you weren't arrested after landing?

 

[Hall]

That's only ~6 miles so while it's not in the direction wireless radios typically aim, maybe it was just some flukes of bouncing signals, especially since you say it was pretty inconsistent.

 

[c502cid]

Hate to tell you but it's pretty common, especially over populated areas.

 

[eljefino]

Surprised the Doppler effect didn't throw the signal out of whack. Any RF engineers to chime in?

On 9/11 people were calling 911 from the air and getting through, and that was a mix of 2G and AMPS.

 

[Astro14]

Some airlines offer free messages through imessage, whatsapp, and others via the in flight wifi.

Free.

Along with in flight updates on the app, and approved 3rd party apps, like Marriott.

So, I can text message, check flight status, and book a hotel, while in flight, and without having to pay.

Very useful.

 

[oil pan 4]

I used to use a dial up internet module on cross country flights.
They said no cell phones, it wasn't a cellphone...

 

[wwillson]

The cellular antenna you see on cell towers are aimed slightly down to keep most of the energy from propagating more than a few miles. This prevents the spectrum in use from interfering with that same spectrum that is use on another tower many miles away. Some RF energy goes out in all directions, this is what your phone connected to. I'm sure it was spotty and unreliable.

 

[RedSpider]

Back in the analog AMPS cellular system days, I was a network analyst for the A-side carrier in Cincinnati. I had a backdoor number internal people could call to discuss network issues with me without getting charged. I had one of the salespeople call me and said he got a bill for like $50 for a call he and I had a few weeks earlier. I checked the number, it was fine, it was fine in the billing system to not charge for it... I then asked him where he was when he called me. He said "Dayton". Same system, those calls routed through our Cincy switching office. I said "Where specifically in Dayton were you, maybe we have the wrong system ID on that tower control channel and the billing system isnt recognizing it as local". He said "Southern end of Dayton, about 6000 feet". I paused and said "Pete, were you in your Cessna when you called me?" and he said "Yea why, is that a problem?" and I said "Yea, I told you not to do that. Your call got picked up by a cell tower in Pittsburgh. Stop calling me from your plane."

A bit of a pause, then I asked "Whats that noise in the background?" and he says "Uh oh......" and I said "Pete, you're in your plane now, arent you?" and he said "Uh, yea, flying over Kings Island right now...."

When you're a mile up, only 0.6 watts of cell signal goes a long, long way.