[smortaz]

not directly relevant, but was riding my motorcycle in the boonies, and lost the phone which was on the handlebar (bumpy rocky path).

Looked for it several times on the path with no luck. Then I remembered my old iPhone was in the backpack. Did a Find my phone on the backup phone and it showed exactly where it had lost touch with the primary phone. This is all without cell or Wi-Fi service. Saved me a $1000.

[JCharante]

You might not want to mount your phone on the handlebar. See: https://news.ycombinator.com/item?id=37230198

[Jeremy1026]

It might also fall off while riding on a bumpy trail and be lost forever unless you have a backup phone in your backpack.

[jojobas]

Having anything to distract you on a motorcycle is a bad idea.

Best to put your phone in DND, if you need directions have them in voice only.

[progman32]

Back when I rode, I made a little arrangement of LEDs around the speedometer in 3 concentric rings of ~32 lights. The blue LED closest to pointing North would light, the green LED would always point towards my home, and the red LED would point towards my destination (programmable before the trip). That's all I really needed. Basically a small version of a navigation arrow above video game characters. It meant that one glance at the speedometer gave me all critical information in one instant. The brain is really good at intuitively figuring out parallax, so if I was moving, two glances gave me a good idea of distance as well, though I experimented with lighting 1,3,5,7,9 LEDs as the destination got closer.

[jojobas]

Sounds cool, even if somewhat likely to get you into a dead-end now and then.

[teekert]

Sounds like a business idea.

[mdpye]

Here you go (2015): https://www.kickstarter.com/projects/ridebeeline/beeline-sma...

I thought it looked fun, but no way to justify the price.

[dmurray]

£40? I guess if they get popular you will see the Chinese version at half that price, but it's hard to imagine a niche product at much cheaper.

The cheapest Garmin watch is about 4x the price.

[lxgr]

Oh, wow, I didn't realize "Find my" worked even when both devices are offline! But it makes sense – all that's really needed is GPS and Bluetooth.

Were you able to access it right there without signal, or did you need to move to an area with coverage for it to sync?

[oldbbsnickname]

Not really. The phone only appears "off" but is in-fact in a low power mode providing beacons. It won't work if the battery were removed.

Also, modern iPhones use tower-assisted GNSS (GPS, GLONASS, Galileo, QZSS, BeiDou, and NavIC) so the satellite isn't necessarily Navistar. With fewer or no towers, and positioned in an odd orientation on the ground, a good fix becomes much less likely, and the range can increase from <1m to 10's-100's of m.

[lxgr]

> Not really. The phone only appears "off" but is in-fact in a low power mode providing beacons. It won't work if the battery were removed.

Sure, how else would it work? But people usually don’t disassemble their phone before losing it on a train/in a taxi etc.

> modern iPhones use tower-assisted GNSS

Yes, but GP says they didn’t have cell coverage where they lost it, so that wouldn’t help.

[megablast]

You had an old iphone you rarely used that still had a working sim in it? So you were paying for two phones every month?

[IggleSniggle]

Internet access is not necessary for Find My to work. Your devices all broadcast their public key over Bluetooth and NFC, and your devices all also have your own private key, and so are identifiable / visible in Find My.

Even if they hadn't had the local map, they can still get some useful signals from Find My (and they can still push Ring requests). However, in their case, their old phone still had the log of the last seen location. Again, no Internet required.

[withinboredom]

He said no service at all. When traveling, and you have an old phone with eSIM support, carrying it with you in a backpack (with eSIM information ready to go) is a good idea. Especially when traveling alone, you never know what will happen. Your primary phone can be stolen, you drop it, or it simply dies and you need rescue.