Funny enough, the UK pretty much promises to let EU airlines continue to fly into the UK and hopes (hope? in a legal process?) the EU would reciprocate. Why would the EU do that? I mean, the EU gets the full deal and the UK nothing? That would help EU airlines quite a bit, wouldn't it?
The same as for flights is actually going to happen to channel ferries and trains. Which would pretty much isolate the UK from the EU on march 30th with the exception of NI.