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  • Request for Opinions on "Airplane mode is a Myth"

K8y This is a wonderful question. It got me thinking since most replies just say Graphene OS airplane mode disables modems and all radios. But does anyone know if this includes the "other brain"... namely the baseband too?

I think there are two kinds of information which might be relevant. One is the GrapheneOS source code, which shows what steps the OS takes when airplane mode is enabled. The other kind of information is evidence that somebody with radio-frequency test equipment could report: if airplane mode is on, is the cellular modem running or not?.

In terms of answers, so far we have one answer from the GrapheneOS project, meaning people who have read the GrapheneOS source code.

So far it does not appear that the GrapheneOS project has hired an RF engineer, or that any concerned community member has hired an RF engineer either.

Meanwhile, there are various "two brains" claims. The people making those claims have not said they have read the GrapheneOS source code (especially not the "iPhones have two brains" people!!), and they also do not appear to have hired an RF engineer to examine the behavior of a phone running GrapheneOS.

In other words, the answer from the GrapheneOS project is based on some evidence, and the notion that maybe GrapheneOS devices in airplane mode actually run the cellular modem despite that is based on no evidence at all.

People who wish to adopt a position that has no evidence at all can of course do that... but why?

People who are concerned that there isn't a report from an RF engineer on the matter might consider hiring an RF engineer, or asking whether somebody at a nearby university is willing to look into the matter for free.

But until somebody breaks out test gear, it seems difficult to defend rejecting the only answer that is based on any evidence at all, meaning the official position of the GrapheneOS project, while re-raising a scary claim that is completely unsupported.

      de0u So far it does not appear that the GrapheneOS project has hired an RF engineer, or that any concerned community member has hired an RF engineer either.

      That sounds like it would be a good investment to be certain that nothing gets out even from baseband. 🙂

          akc3n it's a bit technical for me, but thank you.

            de0u So far it does not appear that the GrapheneOS project has hired an RF engineer, or that any concerned community member has hired an RF engineer either.

            K8y That sounds like it would be a good investment to be certain that nothing gets out even from baseband.

            There may be some difference of opinion, e.g., the GrapheneOS developers might think, based on their understanding of the code, that it is not a good investment, but some community members might think it is.

            Luckily nothing stops anybody from hiring an RF engineer, or approaching people in an Electrical Engineering or Electrical and Computer Engineering department at a nearby university, or even asking a local ham radio with microwave test equipment to take a look. Anybody who feels it's a good investment is free to invest in it -- nobody can stand in the way of such an investigation.

            Edit: But because nobody can stand in the way of an investigation, somebody claiming the cellular modem is on during airplane mode without presenting results from an investigation is not making a positive contribution.

                i remember when they changed airplane mode in like android 11 or maybe even in 10.

                At that time i had root permissions via Magisk on my on my device and not much was hidden.

                I remember reading about the changes discussed in an RFC document but hell if i could find it again.. Things like that are harder to search about today than Android 10 days..

                The devices arent using Data or Internet. They are using P2P, Bluetooth (always on), Samba, SMB, Sharing, Nearby, Beam, sensor data (live data). Possibly wifi direct and a lot more propriatery technology that ISNT open source.

                It's definately the opposite of open source which is why you wont find direct reference to whatever yall think is happening..

                But i can point interested people( who arent gonna stop looking anyway ) in a slightly better direction than multi "brains" .

                in certain south or central american countries, these kinds of networks have become popular for other purposes. Mostly because laws arent enforced in places where politicians lack the ability to enforce trade agreements and other policys (laws, rules, exceptions)..It's happening different everywhere else though

                Anyone remember the days of file sharing? torrenting? Music, videos, art, books, programs, ideas in a general sense used to get shared among others who participated in the event. I am referring to the days of Napster, Limewire, Sharebear, Net Sharing which i guess became Web Share or vis versa...

                  nullable The devices arent using Data or Internet. They are using P2P, Bluetooth (always on), Samba, SMB, Sharing, Nearby, Beam, sensor data (live data).

                  What are you implying here? Are you trying to say that airplane mode isn't working as it's documented to and that other things are communicating via other channels? I can only assume so considering what's being discussed here and how you're wording your post. Many of the things you listed here would be blocked by airplane mode. How do you some of these things work if not via the network or internet?

                  Yes, wifi can be enabled when airplane mode is on, but that means that the cellular radio remains off. Many of the things listed above would work over wifi, as anyone would expect.

                  If I am understanding you correctly, you're also making claims without any evidence whatsoever.

                  nullable Possibly wifi direct and a lot more propriatery technology that ISNT open source.

                  I hope you're not implying that this statement applies to GrapheneOS because GrapheneOS is, in fact, open source. If you're referring to other OSes, like the stock OS or even iOS, then you would need to provide evidence when making such claims.

                  nullable It's definately the opposite of open source which is why you wont find direct reference to whatever yall think is happening..

                  Please elaborate, and if we are actually wrong about what we think is happening, it's up to you to provide proof for your claims.

                        At we moving into “If you can’t disprove it, it must be true” mode?

                        Where is the evidence that any of this is true?

                          Good afternoon, didn't want to create a new topic but I noticed the other day in battery consumption that with flight mode on, wi-fi, gps and NFS disabled. The consumption in system services showed consumption on mobile network from total 51%, IDLE system and small CPU consumption.
                          It turns out that the mobile network still works in flight mode on GraphenOS?

                          • de0u replied to this.

                            Before the topic sinks into oblivion ……

                            We read that airplane mode “shuts down the radios” but it never says both transmitters and receivers.

                            Does anyone have a definitive answer to whether the receivers are shut off in airplane mode?

                            What are the implications if hey remain on ?

                              araviyski Good afternoon, didn't want to create a new topic but I noticed the other day in battery consumption that with flight mode on, wi-fi, gps and NFS disabled. The consumption in system services showed consumption on mobile network from total 51%, IDLE system and small CPU consumption.

                              It turns out that the mobile network still works in flight mode on GraphenOS?

                              I have a vague sense that in GrapheneOS the battery stats are meaningful only between full charges. If I have that right, then the experiment would be:

                              1. Enable airplane mode
                              2. Charge phone up to 100% (when it shows as "Charged")
                              3. Unplug phone while remaining in airplane mode
                              4. Discharge battery significantly (probably at least 20%)
                              5. Review battery consumption figures

                                Blastoidea We read that airplane mode “shuts down the radios” but it never says both transmitters and receivers.

                                Does anyone have a definitive answer to whether the receivers are shut off in airplane mode?

                                Regarding the cellular radio, yes:
                                https://grapheneos.org/faq#cellular-tracking

                                Activating airplane mode will fully disable the cellular radio transmit and receive capabilities

                                Regarding other radios, I can't say it is definitive, but I'm 99.9999% certain "disabled" means neither transmitting nor receiving.

                                  Blastoidea Before the topic sinks into oblivion ……

                                  We read that airplane mode “shuts down the radios” but it never says both transmitters and receivers.

                                  Is that what we read? A source was not cited.

                                  What's on the GrapheneOS web site is "Activating airplane mode will fully disable the cellular radio transmit and receive capabilities".

                                  Does anyone have a definitive answer to whether the receivers are shut off in airplane mode?

                                  What are the implications if [they] remain on ?

                                  Most modern radios use a single oscillator for receiving and transmitting (and the receive path and the transmit path may well share other components, such as mixers and filters). Turning that kind of radio off means that both reception and transmission are off.

                                  Here is an arbitrary article about the cellular modem hardware in an arbitrary Pixel: An examination of the 5G radio in Google Pixel 6 Pro, including this block diagram: https://www.techinsights.com/sites/default/files/2021-12/blog-blockdiagram.jpg. It shows a main modem chip and two band-specific radio chips. If the main modem chip is off, then there will be no cellular reception or cellular transmission on either frequency band -- which aligns exactly with the language on the GrapheneOS site.

                                      Does anyone have a definitive answer to whether the receivers are shut off in airplane mode?

                                      I think there is a serious philosophical question here, namely what various people are willing to regard as a "definitive answer".

                                      Clearly, for some people, the language on the GrapheneOS web site does not count as a "definitive answer". That's fine; everybody is free to decide what sort of answer to accept.

                                      But for me a big question is: If the language on the GrapheneOS web site is not "definitive", what would count as "definitive"?

                                      As I have written before (not just in this thread!), I think the next level down would be hiring an RF engineer, or going to a university lab with RF test equipment, or locating an amateur radio operator with microwave test equipment. Such a person, working from public technical details of the RF modem, will be able to reliably detect whether the modem is or is not running at any given moment. It would then be possible to enter airplane mode and monitor the phone for some amount of time.

                                      But how much monitoring would be "definitive"? One hour? A day? A month? In theory the cellular modem could be designed to self-activate every 37 days!

                                      Also, it would be necessary to repeat the experiment for each device model, and arguably to re-run the experiment for each model every time there is a new firmware release.

                                      So... just what would count as a "definitive answer"? Again, different people can have different standards for that. And it would be great if some member of the GrapheneOS community either did a solid examination or hired somebody to do one (even if it were just one device and just one afternoon).

                                      But if an "overwhelmingly definitive" answer is not possible, which I suspect it isn't, then probably most people will end up having to settle for a "pretty good" answer. Perhaps the answer already on the GrapheneOS web site is close enough? But if not, I encourage people to consider:

                                      1. Exactly what kind of answer would be better than the answer that is already there?
                                      2. What steps can the community take toward an answer like that, assuming the GrapheneOS developers are busy developing GrapheneOS (and also taking into account that people keep expressing skepticism about the statements already made by the GrapheneOS developers)?
                                        13 days later

                                        de0u
                                        I hate to sound contrarian, but I think “are the receivers shut off in airplane mode?” is a pretty straightforward question, with a simple “yes” or “no” answer.

                                        This is getting circular and redundant, so I will desist.

                                        • de0u replied to this.

                                            Blastoidea I hate to sound contrarian, but I think “are the receivers shut off in airplane mode?” is a pretty straightforward question, with a simple “yes” or “no” answer.

                                            The answer on the GrapheneOS web site is "Activating airplane mode will fully disable the cellular radio transmit and receive capabilities, which will prevent your phone from being reached from the cellular network". "Fully disable receive capabilities" means that cellular reception will not happen.

                                            As previously documented in this thread (de0u), in a modern cellular modem there aren't "receivers" as (Edit: discrete, separable) things. So no answer about "the receivers" can be answered in a meaningful way. It is as if the question were "Are the unicorns asleep in airplane mode?". There aren't any unicorns in a modern cellular modem. So I don't think anybody can answer whether the unicorns are asleep or not, not even to provide a "simple yes or no answer".

                                                heh..

                                                this is one of those topics which has "existed from the start".

                                                have watched people put phones in fridges along time ago..
                                                (almost knocking myself out with a face palm heh)

                                                one word; Schematics.

                                                Technical diagrams exist for a reason..

                                                In this context - they are not 'trade secret' IP..

                                                Progressing development of, anything really - doesn't go very far (or well) without collaboration - especially in the context of Electrical Engineering..

                                                Just like the unicorn reference (that was a good one, btw)..

                                                There is a middle ground between source code, and finding someone who doesn't just have specific high end equipment, but also an actual understanding of how to utilise it properly.
                                                (very much including an ability to accurately read the data, in this context)

                                                (also, have an image of 'ghost hunters' in my mind currently..?)

                                                The very term 'hacking' has its origins in this exact arena;

                                                Disassembling a physical device in order to learn and understand how it and its components work. :)