The Mazars law firm, acting as a monitoring trustee on behalf of the UK Competition and Markets Authority (CMA), has invited airlines to apply for slots for three London-US routes released by the members of the Oneworld Atlantic Joint Business Agreement (AJBA).

Prospective carriers have until July 1, 2021, to declare their interest in slots for daily services from London to each of Boston, Dallas/Fort Worth, and Miami International. The airlines can choose whether they want to apply for slots at London Heathrow or London Gatwick. The trustee will then evaluate the applications to verify whether the airlines meet the criteria for new entrants and communicate its ruling by July 22, 2021. Subsequently, approved airlines will have until October 7 to submit a final application for the slots, which will be awarded for up to four IATA seasons starting with the Summer 2022 season in late March 2022 and ending with the Winter 2023/24 season in late March 2024.

If there are no valid applicants, the current holders of the slots may be granted an extension to continue using them for another four seasons.

The slot release process is a consequence of a review of the AJBA by the CMA in 2018. The partnership, comprising American Airlines, British Airways, Aer Lingus, Iberia, and Finnair, was originally investigated by the European Commission in 2009-2010. The probe resulted in slot release commitments agreed upon in 2010 and up for an optional review after 10 years. In 2018, the CMA said it would conduct its own review, considering that five out of six routes covered by the 2010 commitments were out of London and would thus not be under the EU's jurisdiction anymore following the UK's exit from the bloc.

In 2020, the CMA refused to accept commitments made by the IAG International Airlines Group airlines and American Airlines due to the uncertainty resulting from the COVID-19 pandemic. It also said that as its investigation would not conclude by the time the 2010 commitments expire, it would automatically extend them on an interim basis through March 2024. In February 2021, it accepted a slot release agreement awarding United Airlines daily slots for services from London to Boston for six IATA seasons from March 2021 through March 2024.

By the time the interim measures expire in March 2024, the CMA plans to propose a permanent solution to the competition concerns raised by the AJBA.