Originally Posted by NeverFirst

I think the confusion here is the workd "roaming". Roaming means a very specific thing in GSM-speak, and even if you're not "roaming", your handset might still be broadcasting, looking for your home network (and when it doesn't find it, it broadcasts again, but with greater power).

Perhaps you mean "flight-safe" mode, i.e. wireless communications are turned off, but the device is still available for writing messages. Remember, that is still against the rules that we're discussing. Electronic items must be switched off while descending/landing until the plane is parked (and doors opened).