As mentioned, it all depends upon if we are looking at primer or aluminum under that paint. Was the plane painted for the first time, 5 years ago or is it a repaint?
If it's aluminum, you have a slightly bigger issue in that it's likely corrosion and you will need to completely remove it before proceeding with any repainting. If it's a primer to base or single coat issue you only need to remove that top layer, scuff the primer and blend in a new top coat.
One thing not mentioned that, as I understand it, could cause a primer to base/topcoat separation is what is known as solvent pop. The solvents in the primer, is not given enough time to evaporate can become trapped beneath the top coat, causing it to separate. May have been that way for some time and bubbled a little but didn't break up until now. Look around and see if you have any paint "bubbles" anywhere else. We'll keep our fingers crossed that you don't find any.
Other than that, without more information, any one of the replies could be correct.