To repeat what 'flash8' has said, no it's not. you don't say whether you're aiming at aircraft maintenance engineering or aeronautical engineering but I would add one point and it is with your statement "....with possible advancement onto degree level...." I would strongly encourage you to go for a degree. Modern aircraft are becoming more and more sophisticated to such an extent that potential employers are now starting to look for candidates with degrees in addition to technical qualifications. Go for it.