The scope of the retained EU legislation version of the Basic EASA Regulation was amended on exit day (31 Jan 2020 at 2300z) by article 84 of the Aviation Safety (Amendment etc.) (EU Exit) Regulations 2019 (
link). That regulation, and a No. 2 follow up, were made under the European Union (Withdrawal) Act 2018 ("EUWA"). The relevant text in article 2 of the retained Basic EASA Regulation, as it applies in UK, is:
Article 2 Scope
1. This Regulation shall apply to:
(b) the ... operation of aircraft ... where the aircraft is or will be:
(i) registered in the United Kingdom, unless and to the extent that the United
Kingdom has transferred its responsibilities pursuant to the Chicago Convention
to a third country and the aircraft is operated by a third country aircraft
operator;
(ii) registered in a third country and operated by an aircraft operator
established, residing or with a principal place of business in the United
Kingdom;
...
For the avoidance of doubt the Interpretation Act 1978, sch 1, defines United Kingdom as meaning "Great Britain and Northern Ireland." The Crown Dependencies—the Channel Islands and the Isle of Man—together with the United Kingdom form the British Islands but the CDs are not part of the United Kingdom and UK law does not automatically apply in the CDs. Neither did EU legislation outside the scope of Protocol 3 to the UK's 1972 Treaty of Accession which placed the CDs in the EU customs union. Before exit day—interpreted in the Interpretation Act 1978, sch 1, as 31st January 2020 at 11:00 p.m.—article 2 of the Basic EASA Regulation referred to "the territories to which the Treaties apply." That territory is, according to art 52 para 2 of the Treaty on European Union, specified in article 355 of the Treaty on the Functioning of the European Union, specifically para 5:
(c) the Treaties shall apply to the Channel Islands and the Isle of Man only to
the extent necessary to ensure the implementation of the arrangements for those
islands set out in the Treaty concerning the accession of new Member States to
the European Economic Community and to the European Atomic Energy Community
signed on 22 January 1972.
The arrangements referred to are in Protocol 3. Some EU legislation has been voluntarily applied in the CDs and some of which may continue in spite of Brexit, eg EU aviation security standards, the Standardised European Rules of the Air, etc. You can read more in the article
The Channel Islands and the European Union authored by the Channel Islands Brussels Office (pdf
link). For an article on the history of Protocol 3 see Johnson, P.
The Genesis of Protocol 3: The Channel Islands and the EEC. Jersey & Guernsey Law Review. Oct 2013 (
link). See also the Lords EU Committee paper
Brexit: the Crown Dependencies. 19th Report of Session 2016–17. Published 23 March 2017. HL Paper 136 (
link). Specifically see chapter 2
The Crown Dependencies, the UK and the EU. There is also a helpful Ministry of Justice document dated Feb 2020:
Fact sheet on the UK’s relationship with the Crown Dependencies (pdf
link)—here is section 5:
5. Relationship to the European Union
Under the Withdrawal Agreement setting out the terms of the UK’s withdrawal from the EU on
31 January 2020, the Islands’ relationship with the EU as provided for under Protocol 3 to the
Treaty of Accession 1972 will continue until the end of the Transition Period on 31 December
2020.
Under Protocol 3, the Islands are part of the customs territory of the EU. Therefore, EU
customs matters, the common customs tariff, levies, quantitative restrictions and any measures
having equivalent effect apply. There is free movement of agricultural goods and derived
products between the Islands and the EU. Also included are measures relating to the trade in
agricultural goods and derived products with third countries.
However, other EU Rules do not apply to the Crown Dependencies. Implementation of EU
provisions on the free movement of persons, services and capital is therefore not required, and
the Islands are not eligible for assistance from the structural funds or under the support
measures for agricultural markets. [...]
I hope that settles the fact that personnel acting as members of the flight crew of a third-country aircraft, whose operator resides in the CDs, are not required by the retained Basic EASA Regulation or the retained Aircrew Regulation to hold a licence granted converted or validated under the latter regulation. However, such a requirement may still be made in the UK Air Navigation Order 2016. The relevant article in the Order, article 148, has been amended by sch 1 to the Aviation Safety (Amendment etc.) (EU Exit) Regulations 2019 (
link). The amended text has not yet been included in CAP 393 so I will present it here.
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Requirement for appropriate licence to act as member of flight crew of aircraft
registered elsewhere than in the United Kingdom
148.—(1) Subject to paragraph (2), this article applies to any aircraft
registered in a country other than the United Kingdom.
(2) [deleted]
(3) A person must not act as a member of the flight crew which must by or under
this Order be carried in an aircraft to which this article applies unless—
(a) in the case of an aircraft flying for the purpose of commercial air
transport, public transport or commercial operation, that person is the holder
of an appropriate licence granted or rendered valid under the law of the country
in which the aircraft is registered or the State of the operator; or
(b) in the case of an aircraft on a non-commercial flight and where the operator
of the aircraft is neither resident nor established in the United Kingdom, that
person is the holder of an appropriate licence granted or rendered valid under
the law of the country in which the aircraft is registered or under this Order
and the CAA does not give a direction to the contrary; or
(c) in the case of an aircraft on a non-commercial flight, where the operator of
the aircraft is resident or established in the United Kingdom, that person is
the holder of the appropriate licence granted or rendered valid under the
Aircrew Regulation.
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