Interestingly, I have just read a beeb article re the Public Accounts Committee fears over border disruption in the no deal scenario. They claim the Department for Transport has been too secretive about its plans. And the DfT reply:
'The DfT says preparations need to be kept secret to avoid them damaging the commercial interests of the firms involved'
That is pretty much exactly what I am saying above re the "silence" from the aviation sector.