Contrary to popular opinion the EU does NOT need the UK, the converse is arguable and it's easy to get the relevant figures for imports and exports. The problem in many cases is that we have inward investment for manufacturing companies who have tight coupled supply chains across the single market. For them the easiest solution would be to move the plants from the UK to welcoming sites in the EU and ship complete product here just as if we were China, Brazil, India or Tanzania. That makes our balance of payments, GDP and employment position worse. It isn't the only answer though and it affects many other businesses such as financial services (a very big part of the UK economy).
I don't know where this idea originated that the EU does things to us here in the UK , but it makes no sense since we are an influential member and have been for decades, so the vast majority of stuff the EU does is supported and, in a surprising number of cases, initiated by the UK, generally because it makes good sense in terms of socio-economic consistency and good practice. It is true that the implementation goes awry from time to time, partly because Brussels gets it wrong sometimes and partly because of "gold plating" here in the UK. However suggestions that the UK bureaucracy is somehow superior to the EU bureaucracy just reduces me to hysterical laughter........we can't even fix a pothole and tidy up litter.
There are many potential solutions to the issues raised by Brexit, in aviation and many other industries, some very simple in concept. However turning those ideas whether simple or complicated into practical agreed systems to replace the ones we already have requires a lot of effort and many months if not years of time. That then begs the question "What are the benefits of all this work?" so far I have heard not a single plausible answer to that question.