How to configure smartphone/tablet to have no data connection? Before going on a trip overseas with no data plan, I need to check how well my Google Nexus 7 tablet works to geolocate me with just GPS + Glonass + GSM towers.

From experience, I know that just relying on GPS with no data connection pretty much doesn't work: Even after being outside in open skies for hours riding a bike, my GPS-only smartphone had a very hard time geolocating me, and wouldn't follow after it did, while it did work in just a few seconds when connecting to the Net through wifi.

So, I'd like to experiment while I'm still home: Is it possible to configure an Android device to have no data connection and only rely on other means to geolocate the user?

If needed, I don't mind moving to different ROMs such as CyanogenMod.

Thank you.
In theory, any GPS device should be able to decode ephemeris and almanac data from the raw GPS signal, without requiring a wireless connection.  However, I know there are some Android devices that were engineered to supply this data only over a wireless connection.  This is defined at the GPS chipset layer, and typically you can't find any documentation this - you have to actually try it out (or deep dive through online forums to find someone else who has).  To my knowledge there is no way to change this by loading an alternate ROM such as pure AOSP or CyanogenMod, since they use the same underlying GPS drivers.

One way to test is to put your phone in Airplane Mode, turn GPS back on, and then use an app like GPSTest (disclaimer - I maintain that app) and the option to "Clear Aiding Data" to force the GPS back to a clean state.  You'll then be able to see if it gets a fix without a network connection.

Alternately, you can put your phone in Airplane Mode, and reboot it, and then turn on GPS.  This usually clears the assistance data and forces the phone to find a fix again.