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Comment by bitL | Hacker News Reader

Your locations from the time your phone was in airplane mode are uploaded the moment you switch it back to normal Wi-Fi connection. I guess your only choice is going full-on tinfoil/Faraday cage-style though that might be a bit impractical while doing the deeds...

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The entire premise of this is flawed; instead of trying to come up with a way to make the tracking device you're carrying stop tracking, maybe you should just not carry the tracking device in the first place. Leaving your phone at home when go and rob a bank is like Criminal 101.

You might need Maps to avoid traffic on your way out.

And how exactly are you supposed to Uber to the bank and back without a phone??

I'm surprised I had to come this far to find the reasonable answer. Opsec 101.

It's not the only reasonable answer. Leaving your phone powered on and at home works too. Powering it off might stick out, actually.

The comment I replied to said nothing about turning your phone off, only leaving it at home.

> you should just not carry the tracking device in the first place

Baseband processor might be running even on a phone that is seemingly turned off. That's why crime bosses discussing breaking bad always removed their batteries. That might also not work 100% if there were large capacitors inside the phone...

it's conceivable with even the phone powered off that the GPS processor could still be running in an ultra-low power mode doing geolocation fixes every n-seconds and storing them in a cache on the chip.

So I guess a Faraday cage would be the only sure way...

Or turn it off. Or leave it at home.

I've done some neuro/ephys related collaborations where I installed stuff inside a room sheathed in all 6 sides in solid, grounded copper. Inside with the door shut, the wifi and LTE were both good enough to stream video!!! Although, they say it did a good job at cutting the 60hz noise. Personally I would learn a little bit more about Faraday cage design before trusting anything to it besides lightning strikes

Interesting! Do you think the signal propagated through the copper or snuck in through some hole or slit?

High-frequency emissions love long thin gaps. Just grounding the parts against each other is not enough, you have to close the longer gaps, eg with copper tape with conductive glue (sold in electronics shops) and the surface below must be blank too. If you do not do this the gaps might even function as an antenna and amplify the signal.

Also, cables coming outside of your box must be shielded too.

Typically there was a 2" conduit carrying DC power cables and the seam around the door might not have been sealed, so probably that. Also had similar results with fridges, and they have rubber seals on the door gap. So probably leaking through cracks.

If we go into questions of what a maximally malicious phone could do, rather than a question of what a normal phone actually does...

The Faraday cage would still leave the accelerometer fully functional. Now you might say "but because of drift it will rapidly diverge". Yes and no. It turns out that it's possible to detect based on "gestures" where you might be. Works better for winding irregular streets than in a gridlike street network.

If we go full Sherlock Holmes, the microphone might also overhear trains and music from stores giving away the location.

Is that true on Android? On iOS location APIs just don't work in airplane mode.

Android allows the user to turn location on in airplane mode.

Yes, I do this all the time when I'm hiking out backpacking. Without any cell or WiFi nearby I try to save battery by turning them off. When I want to check a location on my map I enable the location long enough to get a GPS fix and turn it off.

I just tested this on my iPhone and location works just fine in airplane mode, even with WiFi off.

I wonder why. Mine doesn't work, it says location could not be determined. iPhone 7, iOS 12.4.

It's probably using GPS, which AFAIK is not affected by Airplane Mode (probably because it's passive?)

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