Multi-national aerial operations use UTC, and from what I can recall of the last set of operational SPINS I saw, they dictate something like "UTC as delivered by the Navstar GPS, modified by the GPS-UTC correction factor available at
www.. "
Tim delivers GMT or BST depending on the time of year. Therefore, since to all intents and purposes GMT = UTC, Tim accurately delivers the global operational standard time (providing you remember to subtract an hour during BST!).