Hi ,
Even in ground trades, personnel who have developed late onset asthma whilst "in service" are subject to medical downgradement dependent upon the severity of the condition. This has the potential to result in loss of promotion prospects and career development and ultimately, discharge from the force.
However, whatever your aspirations are (pardon the pun), it will boil down to the recruiting centre's medical examiner who make reccomendations as to your suitability for sevice.
If they say yes to you, you are sent for tests and if you have been clear for a few years, then it may or may not go against your career choice.
The only way to find out is to go for it and apply. The RAF can always say no as a flyer, but yes to a different career path.
Which ever way it goes, good luck.
Talk Wrench