Apple Maps claims it's 29,905 miles away

Post by kec » Sun, Dec 14, 2025, 7:41 PM UTC

FireBeyond wrote: post #102

kec wrote: post #87

Earlier quoted context omitted.

Civilian GPS (as in, the DoD’s Navstar) alone isn’t accurate enough to actually place you on a specific road. To compensate, auto navigation systems will snap you to the nearest road parallel to your current heading. Tesla likely didn’t consider the edge case of ferries and other off road situations in their mapping software and you hit some corner case bug.

This used to be true, but the DoD turned off "selective availability" (the intentional degrading of the civilian signal) back in 2000, and the current generation of satellites do not have the capability ( https://www.gps.gov/selective-availability ). What they do have though is a separate, encrypted, military broadcast that can be used for those purposes (I think the plan in those situations is to turn off civilian G…

Post by helf » Sun, Dec 14, 2025, 7:50 PM UTC

bragr wrote: post #34

monerozcash wrote: post #21

While we're on the subject of maps-related bugs, I was recently borrowing a new Tesla Model Y and took it on a RORO ferry. After the crossing, the car’s GPS was convinced I was still at the port where I had departed from. I restarted it a couple of times, but nothing. I drove off using Waze on my phone instead of the car's navigation. The map on the car kept moving relative to the direction I was driving, so the navi…

My guess would be: 1. Car entered ferry, loses GPS 2. Car entered dead reconning mode used for tunnels and such 3. Car left ferry, acquired GPS Then either: 4a. Location via dead reconning vasty disagreed with GPS because the car doesn't know about the ferry's movements, triggering some kind of failsafe. Or: 4b. There's just a plain old bug in the condition to switch back to GPS and maybe people haven't noticed becau…

Post by zamalek » Sun, Dec 14, 2025, 7:55 PM UTC

jwr wrote: post #59

monerozcash wrote: post #21

While we're on the subject of maps-related bugs, I was recently borrowing a new Tesla Model Y and took it on a RORO ferry. After the crossing, the car’s GPS was convinced I was still at the port where I had departed from. I restarted it a couple of times, but nothing. I drove off using Waze on my phone instead of the car's navigation. The map on the car kept moving relative to the direction I was driving, so the navi…

> On a vaguely related note, driving 3000 kilometers through Europe in an electric car was surprisingly nice. Having done a number of multiple-thousand km trips in Europe in an EV (not a Tesla, nobody buys those anymore) — it's amusing how non-EV muggles think this is somehow an ordeal. It's just fine! There are drawbacks: you do have to use your brain and plan ahead more than you do when burning dinosaurs. But I fou…

Post by teekert » Sun, Dec 14, 2025, 8:30 PM UTC

worewood wrote: post #43

stockresearcher wrote: post #32

Earlier quoted context omitted.

I had a Volvo XC90 that “jumped” off the interstate and onto a parallel mountain road east of Knoxville. It did its best to track along those roads and somehow made its way into North Carolina. But even when I was back in Chicago, it was still stuck in NC trying to find a way off those mountain roads. Dozens of on/off cycles did nothing. I disconnected the battery overnight and that didn’t work. At the next service a…

A badly programmed Kalman filter perhaps

Post by harrall » Sun, Dec 14, 2025, 8:36 PM UTC

theamk wrote: post #44

hnlmorg wrote: post #42

Earlier quoted context omitted.

The problem is that roads are continually being built and maps aren’t always as quick to be updated. There are also private paths that aren’t public roads but are still intended for vehicles.

That's no excuse for disbelieving GPS for extended periods of time. Google Maps gets it right: it tried to keep you on road, but only for a few tens of seconds. After that, if you are in the middle of uncharted territory, it'll show the marker there. (This is probably because Google Maps can be used for walking/biking too)