Wow ... 54 % into just one (at least medium risk) stock? Some might call that brave, others might use less PC words. Are you sure that you want to take this risk? I guess even if we assume that AIR is not a cyclical stock on the downwards path ... S**t happens in any industry, but particularly in industries who tend to fly people (or ship goods) around the world.
Just imagine it would have been AIR instead of Malaysian Airlines loosing a handful (or just one) plane. How would you than feel about your investment? Sure - some airlines are better than others, but there is no absolute security.
Personally - my limit is 10% in any stock ... and yes, sometimes I allow this number to grow slightly in an uptrend. However - never choose to put more than half of my eggs into the same basket ... Kids - don't try that at home!