I am surprised this is being regarded as important. I have often seen such a difference.
10 degrees over 2000 feet is quite a lot, isn’t it? I haven’t experienced that much very often, personally. It would result in a density altitude in excess of 3500 feet at 2000 feet AGL, your climb performance would be affected in an NA plane?
First, this amount of inversion is not untypical for our Northern climate.
Second, I have seen these warnings before at Heliports, so I wonder is this related to the rotating fraction?
