The latest batch of advice papers also warned food producers that pre-packaged products “would no longer be valid for the EU market”, without a separate EU business address.
Ministers also told motorists that they would need to apply for a green card as proof of third party motor insurance cover when driving in the EU.
And pet owners who want to take their dogs and cats abroad would face the significant inconvenience of having to register three months in advance.
Meanwhile, UK hauliers were warned they could be banned from the continent, because they could “no longer rely on automatic recognition by the EU of UK-issued community licences”.
The Food and Drink Federation reacted with horror to the technical notices, warning they “lay bare the grisly prospect of a no-deal Brexit”.
Layla Moran, a Liberal Democrat supporter of the anti-Brexit Best for Britain, said the threat to flights was “a bureaucratic nightmare and a farce”.
Ministers have repeatedly poured scorn on the prospect of planes being grounded if there is a no-deal Brexit, even though UK-based airlines would lose their operating licences for the 27 EU countries.
A year ago, Chris Grayling, the transport secretary, said: “Flights will carry on. Does anybody seriously think the Spanish government, which would see hotel bookings collapse in 2019, is going to intervene to stop planes flying? Of course, they’re not.”
But the new guidance admits airlines “would lose the automatic right to operate air services between the UK and the EU without seeking advance permission”.
A no-deal Brexit could also force passengers to re-screen luggage and go back through security on, for example, a flight to the UK via Paris or Amsterdam.
The department for transport said its “preference” would be to agree “a basic arrangement or understanding” with the EU – arguing Brussels had already said that would be desirable.
Alternatively, it suggested “bilateral arrangements between the UK and an individual EU country could be put in place, specifying the conditions under which air services would be permitted”.
Under the pet passports scheme, which involves a rabies vaccination and a microchip, people can take their dogs, cats or ferrets to the EU and back again without quarantine.
The technical notice said the UK is pressing to become a “listed” third country after Brexit, to avoid “burdensome” new requirements.
But it admitted that designation as an “unlisted” third country would leave pet-owners having to discuss travelling with their animals to EU countries with an “official veterinarian” months in advance.
UK coach operators were advised to consider subcontracting “all or part” of travel on the continent to EU-based operators, because their licences might not be recognised.
Jenny Chapman, Labour’s shadow Brexit minister, said: “Today's Brexit notices underline why no-deal is simply not an option.
“The British people will be very alarmed to find out that UK and EU licensed airlines would need to seek new permissions to be able to operate in the event of no-deal.”
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