GMT on iphone

Does anyone know how to bring up GMT for the internal clock. I like to keep the phone on GMT while in the air, right now it's easy enough to use London as the time zone, however next month that will be on Daylight time. I realize I can go into manual time set and select a given time, but I'm looking for an easier way. I've tried GMT, Zulu, Greenwich, but there is nothing there, thanks.