Baswell, with aeromed being exempt from the carbon tax on fuel I think you will find that what you heard would have been an entirely 'tongue-in-cheek' comment from the said RFDS callsign. They have good reason for flying at lower level on sectors which could be flown higher. Maintaining a sea level or close to sea level cabin for patient considerations would one reason. Maybe he is now flying a newer machine of the same type (new PC12 or King Air most probably) which has a bit better performance and can manage a higher altitude on the said short sector. Either way I betcha carbon footprint has got nothing to do with it...
