Alfred,
Because he isn't aircrew! GS has managed to get to 3* without doing any 'core' RAF roles since his first 1* tour. That's because those jobs are almost exclusively reserved for aircrew (there are a few engineers about above 1*, and I'm not counting the chief vicar, chief doctor etc). A shrinking pool of aircrew means they will start to edge the other branches out of the non-core jobs in the not too distant future, as a matter of policy (albeit not published). GS has got there just as the window of opportunity is closing.
Whether this is right or wrong is another matter of course.
Last edited by Jacks Down; 21st Mar 2013 at 16:26.