CAA is still following the Government line about exploring associate membership of EASA.
www.caa.co.uk/Our-work/About-us/EU-exit/
Meanwhile the EU has issued a Notice to Stakeholders concerning aviation rights:
ec.europa.eu/transport/sites/transport/files/legislation/brexit-notice-to-stakeholders-aviation-safety.pdf
From the EASA website:
After withdrawal the UK will cease to participate in the activities of EASA and consequently the UK Civil Aviation Authority will no longer need to ensure compliance by UK-based companies with the EU aviation safety legislation.
The CAA can continue to comply with EU regulations but will it be recognised as a competent body to certify those regulations? Unlikely - the CAA doesn’t have the staff or the resources.
From the CAA website - what happens in a No Deal scenario:
The UK withdraws completely from the EASA system in March 2019, meaning that the CAA will need to make arrangements to fulfil regulatory functions without having EASA as a technical agent and without having access to EASA and EU-level capabilities.
The UK is no longer included in EU-level Bilateral Aviation Safety Agreements.
There is no mutual recognition agreement between the EU and the UK for aviation licences, approvals and certificates.
^UK-issued EASA licences and approvals are no longer recognised in the EU post-EU exit.
The EU treats UK airlines as Third Country Operators.^
All licences issued by the CAA under EU legislation, and all type approval certificates and third country approvals issued by EASA under EU legislation, will continue to have validity under UK law, if they were effective immediately before exit day.