If you book a flight planned to depart after 29 March 2019 then do not be surprised to find a clause in the contract such as "subject to the regulatory environment allowing” the flight to take place. On how air operators may seek to limit their liability see The Guardian 4 October 2018.
There have been warnings for a considerable time that Brexit could result in international flights being unable to operate - please see post 19 July 2018 - Brexit and Civil Aviation . In that post I noted the UK government position regarding civil aviation as set out in the White Paper - The future relationship between the UK and the EU - and also included an overview of the existing Civil Aviation Regulatory system.
The EU issued Brexit Preparedness Notices addressing numerous sectors including Air Transport and Aviation Safety and see the EU Commission's Air Transport Notice 11th December 2017.
Today, the government issued further documents in its series "How to prepare if the UK leaves the EU with no deal." The papers concerning civil aviation are:
"a scenario in which the UK leaves the EU without agreement (a ‘no deal’ scenario) remains unlikely given the mutual interests of the UK and the EU in securing a negotiated outcome.
Negotiations are progressing well and both we and the EU continue to work hard to seek a positive deal. However, it’s our duty as a responsible government to prepare for all eventualities, including ‘no deal’, until we can be certain of the outcome of those negotiations."
After the events at Salzburg last week - see this post - it must seriously be doubted that things are actually progressing well though we hope that they are.
: Passenger rights :
The documents state:
"For air passengers on a flight departing the UK, the same passenger rights as apply today would continue to apply after the UK left the EU. EU passenger rights legislation will be retained in domestic law by the Withdrawal Act.
Passengers subject to denied boarding, delay or cancellation, would be entitled to assistance and compensation on the same basis as today
Passengers with reduced mobility would still be entitled to the same assistance from airports and airlines
UK consumer protection in the event of insolvency of a travel provider would continue to apply