The UK government has released the latest batch of papers advising British people and businesses about how to prepare for a no-deal Brexit. The papers include warnings on potential disruption citizens may face traveling into and from the European Union (EU) by air.

This is now unfolding as a real possibility and to such a degree as previously highlighted when the issue was addressed at the March 1 US Chamber of Commerce, annual aviation summit in Washington DC.

As the UK prepares to leave the EU on March 29, 2019, airlines have started to sell tickets for travel that they may not be able to fulfill. This is because these flights would then not be covered by Open Skies aviation agreements. In addition, flight frequencies are not yet agreed upon with respect to flights between the UK and the EU.

While the UK has notified the European Commission of its decision to leave the Union and negotiations are underway, the form of the future relationship has not been agreed. If the UK completes its departure from the EU in the absence of a withdrawal agreement that includes transition arrangements, the implications for aviation are significant.

If no agreement is reached, including some sort of temporary or emergency arrangement, flights by UK carriers to or within the EU, and flights by EU carriers to, or within the UK, will need to be suspended, leading to unhappy travelers, potential job losses and an impact to the bottom line of airline companies.

There are three overriding agreements on the table among the involved parties and each needs to be renegotiated.  The first of these will follow the UK no longer being a party to the US-EU Open Skies agreement. If the US and UK wish to retain an Open Skies agreement between themselves, they must negotiate a new Open Skies treaty. This has never been done before. Currently, the US-EU agreement is only being “provisionally applied” because it hasn’t been fully ratified by all EU signatories.

If a formal agreement is not in place by March 29, 2019, the Bermuda II agreement—which was considered highly restrictive compared to current agreements—would take effect. The US and UK are reportedly well along toward putting in place a new bilateral aviation agreement, so most observers expect a solution to be reached.

In the case of the second of these agreements, having the UK within the US-EU Open Skies agreement has been a benefit to the US. This is because it gave US carriers more access to London Heathrow, albeit with limitations in the form of limited availability of prime slot pairs. When Heathrow drops out of the equation through Brexit, the US-EU bilateral aviation agreement will not offer the same benefits to the US. Although this agreement has not been ratified by all EU signatory countries yet, most observers do not believe that the US will seek to renegotiate it.

But the real problem lies in the need for a new arrangement to govern flights between EU countries and the UK. Unfortunately, very little progress has been made between the UK and EU negotiators tasked with negotiating a new aviation agreement. This heightens uncertainties for the American Airlines-British Airways and Delta Air Lines-Virgin Atlantic joint ventures in terms of traffic rights to carry passengers beyond Heathrow to/from the EU. Those joint ventures represent more than two thirds of the traffic between the US and UK and over half of those passengers flow on to the EU or from the EU on to the US.

A new bilateral agreement is needed to allow UK and EU carriers to fly between their two territories – or by allowing the UK admission to the European Common Aviation Area (ECAA), in a similar way that countries like Norway and Iceland operate. It would also allow the UK to access the other non-EU countries that have signed up to the ECAA.

There would, however, be challenges: the agreement currently makes no allowance for members to change their current membership status, as the UK will be doing. It's possible that the EU would see such a move as the UK cherry-picking. Separately, an additional “horizontal” agreement would need to be established to allow EU carriers to originate transatlantic flights from the UK.

Brexit also raises other issues for carriers operating to and within the UK and EU, whether based in those jurisdictions or in other countries. The most pressing of these may be on the issue of safety regulations and whether the UK will continue to be subject to EASA’s jurisdiction.  But there’s also the question of the application of the EU’s Emissions Trading Scheme to UK airlines, rules governing the movement of aircraft parts, and possible restrictions on the hiring of EU and UK citizen employees, with language and other required skills on each other’s jurisdictions.

The fundamental issue is what will cause the UK and EU negotiators to be motivated to put these negotiations into high gear? And, even if a transition agreement covering the aviation industry can be reached in rapid fashion, however unlikely that seems right now, will such an agreement require ratification by all 27 EU signatory countries to take effect?

What seems clear is that the EU-UK aviation solution will likely not be in place for many months and may very well come down to the wire.

Considering the major impact of Brexit on the global aviation industry, a transition agreement covering the aviation industry is needed as soon as possible, not least because of the direct relationship between air service and a country’s GDP.

John Luth leads the global aviation consulting and corporate advisory practice of Seabury Consulting, now part of Accenture.