Why would ports and airports have to be closed to EU traffic?
Stopping altogether is probably going to be short term as the shock of no deal kicks in. After that...because each and every box of oranges, lorry and flight from the EU will now have to be checked in the same way that everything from outside the EU is. Tariffs will need to be paid on goods that don't currently get paid. Customs will no longer have roll on, roll off delivery of foods and other goods, but each and every single lorry will need to go through customs which will take hours. And there's compliance; goods sold in the EU adhere to certain standards, but now everything will need to be checked because we will be outside the standards laws. Customs will effectively grind to a halt. You know that the government are planning on using an entire motorway as a freight lorry park? Remember how strikes in France brought Dover to a standstill? That, only day in, day out, with no goods reaching our supermarkets. We will have enough food to last 6 months. It is our government who are recommending stockpiling and I do not think it a coincidence that my local supermarket has big promos on things that aren't generally popular here such as tinned soups. And there are all kinds of sectors in manufacturing that rely on the supply chain of goods from Europe and that will end because they can't turn around their stuff quickly enough. Rice is currently milled in this country and taken back abroad to be sold. That is ending. And it's a big employer across the county border from me. And that is just one example. Productivity across all sectors will be hot and companies will move elsewhere.
And that's without a load of technical shit I don't understand. Air traffic control? That must be an EU thing.