GPS was not working while I was in Europe

I am not an expert with GPS but I will try to offer the likely explanation. You were on vacation and so I am making two key assumptions here: firstly you did not use data roaming, and secondly there was limited access to free public wifi when you were firing up the GPS.

GPS location is actually quite a slow business - the GPS needs to have quite a lot of information about the relative positions of the various satellites before it can get a fix. The swift precise locations that many devices, especially the iPhone, can get are a result of something called Assisted-GPS. You can search for this but explanations of how this relates to the iPhone may be found here: arstechnica.com/apple/news/2008/06/assisted-gps-and-the-iphone.ars and here: gizmodo.com/5015930/giz-explains-what-you-didnt-know-about-the-iphone-3gs-gps. In a nutshell, if the GPS does not know roughly where it is to start with then it needs to have substantially more information downloaded to it - the ephemeris data - and this is a slow process from the GPS satellites. The alternative of A-GPS needs an active internet connection, such as you normally have through the cellular network or as you would have had while you were in the Apple store in Amsterdam.

Put simply, and speculatively, you never waited long enough for the GPS to acquire sufficient new ephemeris data and there was no other means for it to be acquired through a data connection instead.

Now I may be completely wrong about this, and I stand to be corrected by those more knowledgeable, and if you did have data roaming enabled then this is definitely wrong (but you must have spent a fortune in that case!).

Anyway, I hope it didn't spoil your visit to Europe too much! 😉

While you were in europe was your phone in airplane mode? If so, ALL radios are turned OFF, including your GPS chip. While you can turn WiFi back on in settings, the GPS chip cannot be turned back on if the phone is in airplane mode.

gordiasUK is right.
To use GPS without the help of an underlying data connection, it can take several minutes to start obtaining a GPS signal. You only thought you didn't have GPS because it was taking longer then usual. Remember, it can take several minutes!

Some things to notice:
-Although you have to wait a while to get a GPS signal, once you get it, it works like usual. The Phone needs to get what's refered as an 'almanac'. It's basically a 'map' that says to the GPS how it should interpret the satellites signals (also, it synchronizes it with the satelites).
-Whenever you stop using GPS, if you connect it again very close to your last used location, the signal will come quicker. Always good to have that in mind.
-In order to get a signal quicker, make sure your phone has as much visibility of the sky as possible. If you are in a car, put in near the front window. Basically, imagine that the more sky the phone sees, the faster you'll get that first GPS signal.

The guys at the apple store should have known better, and have clearly explained to you how GPS works. So, GPS will work next time you travel abroad, just remember that it takes a while to get that first signal.

cheers

The fact of the matter is simply that the GPS radio chip is turned OFF when the iphone is in airplane mode. I don't know what you mean by your statement that you tested before you left. In airplane mode the GPS chip is off.

You cannot turn the GPS chip back on when the phone is in airplane mode, its as simple as that. I have no idea what the Apple store people were referring to.

Quoted from the manual:

"When airplane mode is on, Airplane icon appears in the status bar at the top of the screen. No phone, radio, Wi-Fi, or Bluetooth signals are emitted from iPhone and GPS reception is turned off, disabling many of iPhone’s features."

It is possible that your location may have been determined by wifi, if wifi was turned on, while in airplane mode, but it certainly was not by the GPS chip unless your phone is defective in some way, which is highly unlikely.

FYI- I just put my iPhone on "Airplane mode", and then I checked to see if the GPS would work- when I tried to access the GPS feature, I got a pop up message that says, "Turn Off Airplane Mode or Use Wi-Fi to Access Data". When I changed my settings to connect to wi-fi while in airplane mode, it allowed me to use the GPS function.

I don't believe you can access GPS on Airplane mode without being connected to wi-fi.

Were you connected to wi-fi when you tested the GPS at the Apple Store in Amsterdam?

I'm pretty sure GPS does not work if Airplane mode is ON. I could be wrong, of course, but I don't think it works. What some applications do, is simply show your last known location, but it doesn't really update. Google maps does that.

You can use GPS without both Wi-Fi and cellular connection, it just takes longer to make a connection. The people at the apple store probably deactivated airplane mode? That might have been it. Why would you want to keep airplane off anyways?

Even if the GPS connection works with airplane ON, it would take several minutes to establish a connection. For example, if you device only sees one sattelite, it would take it 40 minutes to download a complete almanaq. of course, you'd need at least 4 (3 if they have made a simple improvement) sattelites to get a signal. Since sattelites share the almanaques at different times, that time is cut short. When you have a Wi-Fi/GSM connection, your device 'immediately' gets all the needed information, that's why it's faster.

So, are you really sure your GPS was working in the states with Airplane ON? Or was it just showing a cached location?
Also, are you sure your device was not connected to he store's Wi-Fi connection? That would considerably speed up the GPS acquiring signal.

Another note, most GPS devices (I'm assuming the iPhone does that) store the latest information, so that the next time you reconnect, getting that signal will be much faster (as long as there's not a long period since you last used it).

Assuming you used the iPhone back in the states, you'd have been covered by different sattelites in each of the visited countries, so you'd really need to wait for the full information. For the first time at least.

Anyways, no Wi-Fi or cellular connection, means you'll have to wait several (5~15minutes tops, usually) to get that first GPS connection. It should work much faster the next time you use it at the same location, though.

And to finalize, there is absolutely no reason for your GPS not to work outside the US, unless you had some kind of jammer with you =D. GPS works by receiving signals, it does not in any way communicate with anything else. If you did not get a GPS lock, you either did not wait enough, did not actually have GPS on, or the applications you downloaded had some problem.

cheers!

belovejs:

GPS works without Wi-Fi. What happened is the following: currently, the iPhone can locate you based on GPS and/or Wi-Fi. It is a solution based on Skyhook (google it - I think it is actually Skyhook that is used).

Anyways, Airplane ON disables GPS. Thus why yo got two choices: disable Airplane mode, so you'd get GPS, or enable Wi-Fi, so you'll get Wi-Fi based location. Wi-Fi is less reliable, and has less accuracy, and requires a woking internet connection. It can be used inside buildings though =)

Since everyone else is correctly telling you that GPS cannot be ON in airplane mode let me ask how is it that you are so sure that the GPS was on? What are the apps that you mention - you say you spent a lot of time preparing for your trip and testing. Maybe we can help figure out what exactly was happening if any of us are familiar with these apps, and you also say you downloaded map data - how, in which app?