There are a number of difficulties associated with shooting from light aircraft...

• Reflections
• Camera Shake
• Haze or poor light
  
• Coloured/tinted window perspex creating filter/colour cast effects
  
• Window perspex scratches and insects splats
  
• Propeller and wings in the way
  

Normally I don't use images with significant reflections, window defects or with camera shake, though I will sometimes use photos with only minor reflections or window defects if the picture is otherwise good.

With other faults, I'm sometimes left with the dilemma of whether to include a photo at all or perhaps over-process it in order to remove haze and try and re-balance the colours and remove colour casts and tints - unfortunately this can often result in high contrast and almost "false" colours - in many cases I have included such photos on the site rather than not have a photo of a particular subject at all.

As for propellers and wings - I tend to leave them in or try and crop them out as appropriate - in many pictures they are apt to leave in.