Captain: that doesn't invalidate the argument. If they did this to simply save fuel, regardless of carbon tax then it proves there are savings to be had everywhere if you look for them.
Are you really trying to tell me that we need a carbon tax to encourage us to try and save fuel and that without it we will be less efficient at our job?
Now, stay high, reduce fuel burn and have more headwind = stay in the air longer and burn more fuel or go low and go go go and burn more fuel?
Will the new mantra be 'safety and carbon footprint before schedule?'
Hmm...
