[jbmchuck]

Honest question - what's your use case for needing GPS indoors? I generally know where I am when I'm indoors :)

[mcdonje]

You're in a large building you're unfamiliar with. Particularly one with an unusual layout, like a mall or hospital.

[InitialLastName]

For a variety of reasons I've set a personal best for time in large hospitals in the last year. They can be very difficult to navigate in the best of times, much less in the less-than-ideal mental state that often accompanies time in a hospital.

[denysvitali]

Maybe indoors is the wrong term: as soon as you don't have direct sky visibility it's relatively hard to get a position.

Some examples: on a train, on the underground, in a train station, in a mall, in an office building, ...

[wongarsu]

Probably depends on the construction of the roof and windows. At least on European trains I've never had an issue getting GPS (unless you are in a tunnel or subway system). It takes a bit longer to get the first fix if you don't have AGPS, but no worse than in a car. Same with planes. On the other hand in a building it it pretty much only works next to a window, and malls don't have windows

[seba_dos1]

Even if you do, it will often take more time to acquire a fix than most people are used to

[HPsquared]

It's useful in shopping malls, airports, train stations, car parks and so on. Anywhere you need to navigate a large complex.

[mingus88]

Not OP but navigating large malls, subway terminals, etc is nice