If agreements are not signed by March 29 2019 flights could be grounded, according to Scottish Government.
Her spokesman said later that May was specifically referring to the type of deal the European Union is now offering on future trade, which Britain believes will split England, Wales and Scotland from Northern Ireland by insisting Northern Ireland adhere to different customs rules.
As a back-up, the United Kingdom government is speaking to the individual member states about establishing bilateral agreements for aviation, based on pre-existing arrangements. And while country-to-country flights could continue under bilateral agreements, intra-country flights by foreign carriers could not.
He said Labour was saying to Leave voters "that we will deal with the situation as it comes up and we will understand, many of them, the reasons why they voted Leave".
The UK says it would seek to agree a new multilateral agreement between the UK and the European Union states, or bilateral ones with individual countries if that is not possible.
For instance, in a potential headache for some parts suppliers and maintenance firms, the papers said the EU's indications are that it would not recognize some safety-linked certificates issued by the CAA, meaning that UK-certified parts could not be installed on EU-registered aircraft, and UK-approved engineers would not be allowed to work on them. This may involve a small extra fee from the insurer.
Pet owners hoping to travel to Europe with their pets may face months of preparation before their trip in the event of no-deal.
Speaking to reporters on her way to NY to attend the United Nations General Assembly, May said she welcomed comments from European Council President Donald Tusk that the bloc still wanted to strike a deal, but added that the onus was still on the EU to break the deadlock on Chequers. But the situation is more complicated for regular coach services, such as those operated by National Express, which this would not cover.
Chief executive of the Food and Drink Federation Ian Wright said the technical notices laid bare the grisly prospect of a no-deal Brexit, including chaos at the ports, serious disruption to food supplies and more administrative burdens on the food and drink industry. It will potentially leave tourists stranded overseas and make holidays more expensive and inconvenient for millions of people.
"If the prospect of the choice is between a crash out no deal scenario and another referendum, I think that's what they would go for".