The Civil Aviation Authority was reportedly rebuffed when it sought a joint no-deal transition plan with its EU counterpart.
Correspondence seen by the BBC show the European Aviation Safety Agency (EASA) rejected the UK regulator’s call for a plan in the summer.
The two bodies are yet to begin formal discussions with months to go before the UK could drop out of the EU without a deal.
EASA said technical talks could not pre-empt political agreement on Brexit.
In a letter to EASA in June, CAA chief executive Richard Moriarty said a “joint transition plan” was necessary to help assure people of “the on-going integrity of the aviation framework in any future scenario”.
It said: “My team is standing by to support these discussions.”
In response, EASA executive director Patrick Ky said he understood the request to limit disruption and safety risks.
But he added: “It remains the case that without sufficient clarity on both the outcome of the withdrawal process and the future UK legal framework such discussions would currently be premature.”
If the UK leaves the EU without reaching a deal, the EU would not recognise certificates, approvals and licences issued by the CAA.
This could stop new aviation parts made in the UK – like wings constructed by Airbus – being put on EU aircraft.
British pilots with UK licences flying EU-registered aircraft would need to get second licences from another EU state or transfer their licences there.
EASA said in a statement to BBC Radio 4’s Today programme that Brexit negotiations were ongoing and added: “The outcome of those negotiations cannot be pre-empted, but until more clarity is gained of the terms of UK’s withdrawal, discussion about technical details would not be useful since the framework for which we need to prepare is not known.
“Such technical-level discussions cannot pre-empt the overall political agreement, which is the subject of the withdrawal negotiations.
“Once the future framework is clearer, we will be open to engaging also in technical discussions.”
The CAA said the UK would recognise safety licences and approvals issued by EASA and it urged EASA to recognise its own after Brexit.
A spokesman said: “We call upon the European Commission to allow EASA to hold discussions with us about the detailed technical arrangements that would apply in a no-deal scenario.
“We are ready to start these talks immediately.”
The UK wants to participate in EASA after Brexit. Failing that, officials seek a deal where the EU and UK aviation authorities recognise each other’s standards.
EASA has recently offered some UK aviation businesses the chance to be approved as “third county” suppliers to the EU, which means they could carry on doing business in the EU.
But not all areas of aviation are covered.
Although there are international agreements, there is no aviation equivalent of the World Trade Organisation that would allow flights to continue seamlessly after a no-deal Brexit.
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