PPRuNe Forums - Mobile phone signal interference... all lies??

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- - Mobile phone signal interference... all lies?? (https://www.pprune.org/tech-log/237110-mobile-phone-signal-interference-all-lies.html)

I'm going on a 767 can i use my digicam on takeoff and landing, i always see videos on a-net and flightlevel350

Thanks for that interesting link john_tullamarine. While it doesn't answer my query about what happens if the picocell dies, it raises further issues:

Quote:

Strauss: There's good news and bad news about pico cells. The good news is that with the pico cell on board, most cell phones go to low power.

The bad news is that it's highly likely, for example, that Sprint may win the contract [to provide in-flight cell phone service] with United and Verizon winning the contract with US Air, and you'll have different services on different aircraft. The passenger is not in tune with what service the airline has, so he's going to turn on his phone and try to use it. And if it's not compatible, no one has convinced me that the pico cell will be able to tell that person, "You can't make a call here."

Avionics: The phone won't be low power?

Strauss: Right. His phone will be screaming. We had clear, concrete rules in the past--you cannot use your cell phone during flight, period--and people still used them with some consistency. I guarantee you that with pico cells, everyone will try to make calls. And with what we talked about with the intermodulation and what NASA has found, it's a bad path to go down, unless we're doing some other things to monitor the situation.

Quote:

Originally Posted by 411A

>>Something else to add. GPS landing systems will be comming into vogue more and more. GPS radio waves operate around the 1 - 2 Gigahertz range which is close to the mobile phone frequency.<<
Dunno if it's close to the GPS frequency or not, but this was tried as well on my little un-scientific test.
If have two different GPS receivers on board and neither were bothered in the slightest.
Perhaps just lucky...:uhoh:

Times I've accidentally left my mobile on in my flight deck (which in this case is a handy little bum-bag style thing for carrying one's instruments with velcro on the top for in-flight use!) I've not noted a GPS problem. Not heard any other free flyers note it either. Variometers, OTOH, go absolutely nuts, becoming completely unusable. In fact it's normally the first sign one has left one's mobile on. Makes it bloody hard to thermal! ;)

It would obviously not be surprising if the instruments on commercial aircraft were rather better shielded but it's concerning all the same.

Like many, I also don't want to be in a cabin with people on their mobiles for air rage minimisation reasons! :)

Cheers,

Rich.

In the Dash-8, there have had a couple of instances of cellphones being used in the cabin's rearmost seats creating interference with the baggage compartment smoke detection system, causing the smoke warning light to come on in the cockpit. This on one particular occaision occured in flight; with no other way to verify whether there was actually a fire or not without opening the aft bulkhead door and potentially endangering everyone on board, the crew donned the full oxygen mask / smoke goggles regalia, declared an emergency and diverted to a nearby airport.
On the ground they discovered 7 people in the back rows with cellphones turned on, several of whom had apparently tried to sneak out a call while the flight attendant was busy in the front, pretty much simultaneously. There were some choice words said, and stiff fines imposed, from what I understand.

Interesting report on the Australian Forum where there is evidence that using a mobile phone can interfere with transponder signals causing intermittent transponder read-outs as seen by ATC.

Quote:

Originally Posted by Old Smokey

Try operating coms on 133.4 and have one of your passengers operate a "Blackberry" phone. Not strictly a mobile phone in the conventional sense, but a mobile phone on a different frequency nonetheless.
133.4 is an exact harmonic, and reception of this frequency is perfect, reception of the phone caller that is! As for ATC, you can't hear a damned thing!
Regards,
Old Smokey

Sorry, I find this a little bit difficult to believe:
1) Blackberry phones are digital, either in their GSM or iDEN versions. No conversation can be heard by a conventional analog receiver.
2) 133.4 is an exact harmonic of what? All mobile networks use multiple frequencies (channels), so unless you know which exact frequency a cellphone is using at a given time, you cannot make any assertion like that.

DISCLAIMER: before someone jumps in for the 465754th time saying "just switch it off" ..

I'M NOT ADVOCATING USE OF CELLPHONES IN FLIGHT.

Sorry for the uppercase.

Dunno if it's relevant or not, but we used to get the FMSs split into independant operation on the F100 from time to time.

Although it would happen anywhere, a regular place was at DPE on the descent into CDG from the UK. For any phones left on this would be their first chance of registering on the French networks.

Conclusive eveidence, no. But it was often enough to make me wonder.:confused:

I think enough pilots have rung in on the topic Journo123 (we never completely agree on anything ;) but I would say the majority rules on this one :}