I know but how hard is it to shoot down a non maneuvering aircraft? Personally I never tried but looking at the thousands of pilots from WWII this should be very easy. I can understand you can miss on the first pass, but 5 passes??
Did you ever think that the SOP was to disable the aircraft and not destroy it? You are quick with your words and obviously short on thought in your analysis of the situation. I'd be willing to bet the Colombian pilots are quite professional and are able to hold their own in most situations. If they really wanted to destroy that aircraft that would have turned it into dust the first attack. The T-27 pilot simply hung out on the dead 6 of the target and fired a few short burst on multiple setups (I hesitate to call them "passes"). Perhaps they were first trying to force the target down to land, disable it from flying further, etc, etc.
Remember, if you capture the plane, pilot, passengers, and cargo you can do more damage to the cartel's operation than if you simply destroyed/killed them.