Business lobby group the Aerodrome Coordinating Authority has issued a stark warning about the potential loss of the UK’s aeronautical and biofuel sectors after Brexit, saying it is set to lose “critical financial assistance” following Brexit and represents an “obstacle” to sustaining the industry.

The Aerospace Alliance, an industry body which includes Airbus, Boeing and Leonardo, has said “the integrity of the UK’s aviation sector and civil aviation infrastructure is at risk” after Brexit – an assertion supported by a breakdown of the UK aerospace industry’s 2015 membership of the Aerodrome Coordinating Authority (ACA).

Wealth of information in the ACRAS and the ACF is now shared by other member countries, further eroding UK industry’s ability to benefit from governments’ decision-making.

Our membership could not contribute to the EU’s key European Single Aviation Area policy objective – reducing the distance between regional airports – without the UK.

The last of the UK’s 54 Aerodrome Coordinating Authority locations closed last year, alongside the Passport Services, Civil Aviation Authority and National Air Traffic Services.

The UK was given a four-year extension to the period of membership in December 2017. The ACAs “stipulated that the remaining member states in this initiative must have access to UK parts”, writes former BAE Systems and Qinetiq senior vice-president Michael Pooler.

“In this way, for example, the durability of the UK’s multi-industry [aeronautical] consortium and its development of new fuels and related technologies cannot be questioned.”

The Aerodrome Coordinating Authority has few UK members any more and Mr Pooler suggests most of the more than 300 members in 2015 have since left the association, without being replaced.

A spokesman for the Aerodrome Coordinating Authority declined to comment on the claims, with a spokeswoman for the UK Civil Aviation Authority noting that it does not take a position on departing ACAs.

The UK declined to sign on to the European Single Aviation Area in 2003 because the EU imposed airspace restrictions as a “protection mechanism”, preventing the UK from flying direct to European destinations without negotiating commercial agreements with the EU member states.

The Aerodrome Coordinating Authority was the only UK membership organisation of the European single aviation area which was not affiliated to either the European Union or the International Civil Aviation Organisation (ICAO).

This lack of affiliation means the UK cannot take part in decisions made on behalf of all UK aviation users, such as the new Belfast-Moscow direct route, “or authorisations for new routes and the transfer of UK airspace”, says the Aerodrome Coordinating Authority.

The position of a single member in the Aerodrome Coordinating Authority with less than complete geographical coverage “reduces the credibility of the ACRa, especially when the UK is excluded from an area as significant as the Single European Sky and refuses to take an active role in its development,” says the Aerodrome Coordinating Authority.

Airbus and Bombardier have publicly expressed concerns about potential disruptions to aviation traffic in Ireland, which they both use as hub operations for international flights. The Aerodrome Coordinating Authority says this has been exacerbated by the lack of attention to the future availability of the UK area under membership of the Single European Sky.