Research and analysis

RPC opinion: airport slots regulation

Published 12 June 2026

Lead department: Department for Transport

Summary of proposal: to create enabling powers in primary legislation that would allow the government to update airport slot regulations when necessary. This would provide permanent powers equivalent to those available to the EU, replacing temporary powers previously used to amend slot regulations.

Submission type: options assessment – 4 August 2025

Legislation type: primary legislation

RPC reference: RPC-DfT-25071-OA-(1)

Date of issue: 19 August 2025

RPC opinion rating

Fit for purpose:

• the department provides a reasonable case for the need for permanent enabling powers to update slot regulations
• the proposal provides powers rather than implementing specific regulatory changes, which limits immediate impacts on business
• the department should explain at impact assessment and secondary legislation stage, how use of powers will be guided by clear governance tests - competition and consumer screens - to avoid protectionist outcomes
• the department has identified that substantive impacts would arise from secondary legislation enabled by these powers, which would require separate impact assessments

RPC opinion summary

Rationale: Green

The options assessment (OA) presents a case for establishing permanent enabling powers for updating slots regulations, explaining that the powers would replace temporary solutions previously used to amend slot regulations. The international context is explained, noting the importance of maintaining alignment with global slot coordination practices. The department should explain at impact assessment and secondary legislation stage, how use of powers will be guided by clear governance tests - competition and consumer screens - to avoid protectionist outcomes.

Identification of options: Green

The OA has considered a limited set of options, including a non-regulatory option (issuing guidance) and the preferred option of enabling powers. The department has applied the Green Book’s Options Framework Filter, assessing longlisted options against objectives and critical success factors.

Justification for preferred way forward: Green

The department has provided a justification for the preferred option, showing how it meets identified objectives and critical success factors. The OA acknowledges that the primary legislation would create minimal direct impacts, as costs and benefits would arise primarily through related secondary legislation.

Regulatory scorecard: Satisfactory

The department provides a qualitative assessment of impacts, as the proposal concerns enabling powers, rather than specific regulatory changes.

Monitoring and evaluation: Weak

While the department notes that detailed plans are expected at related secondary legislation stage, it should still consider an overall plan at this stage, arising from the proposed primary legislation.

Summary of proposal

This intervention seeks to create enabling powers in primary legislation that would allow the government to update slot regulations when necessary. These permanent powers would replace temporary powers previously used to amend slot regulations, and would be equivalent to those available to the EU.

The proposal aims to provide regulatory certainty and flexibility for the government to respond to international developments in slot coordination, or take UK-specific approaches when beneficial. The proposal enables powers and means substantive impacts will arise from secondary legislation enabled by these powers, which will require separate OAs.

The department notes that without permanent powers, the government would need to continue relying on temporary legislative solutions, which creates uncertainty and inefficiency in the regulatory system.

The OA has considered 2 main options:

• option 0: issue guidance - provide clarifications and non-binding interpretations of existing legislation that would not be enforceable for the slot coordinator
• option 1 (preferred option): establish permanent enabling powers for the government to update slot regulations as needed, putting UK Government powers on a par with those available to the EU

As the proposal is for primary legislation that only grants enabling powers, there are minimal direct costs or benefits to businesses, arising from the primary legislation. The OA therefore takes a qualitative approach to assessment, using recent changes to slot regulations enabled by REUL Act powers as examples, to illustrate the scale and type of potential future interventions.

Rationale

Problem under consideration

The department identifies the need for permanent enabling powers to update slot regulations, explaining these would replace temporary solutions previously used. The OA establishes that the powers would be equivalent to those available to the EU, putting the UK Government on a par with EU capabilities in this regulatory area.

The department should explain the slot market better, for example how much a slot costs, how barriers to entry into the market are prevented, and how the legislation fits in with wider slot reform. The department should also explain how, The Airports Slot Allocation (Alleviation of Usage Requirements etc.) Regulations 2025 can be implemented without new powers, and therefore why new enabling powers are needed.

Argument for intervention

The department presents a strategic case for intervention, emphasising the international nature of slot coordination and importance of maintaining regulatory flexibility. The OA explains that without permanent powers, the government would need to attempt to rely on temporary legislative solutions, creating uncertainty and inefficiency in the regulatory system.

The OA could identify more explicitly the specific market or regulatory failure. While the need for permanent powers is established, a clear articulation of how the current situation leads to suboptimal outcomes, would strengthen the OA. The department should explain at impact assessment and secondary legislation stage, how use of powers will be guided by clear governance tests - competition and consumer screens - to avoid protectionist outcomes.

The department should set out how the approach interacts with emerging reforms considered domestically and internationally (including market‑based mechanisms such as auctions) to ensure interoperability and consumer benefit.

Objectives and theory of change

The OA identifies high-level objectives for the proposal, focusing on ensuring that slot regulations can be updated as needed and avoiding reliance on temporary legislative solutions. These objectives are assessed in the options evaluation table where the preferred option is shown to meet both objectives.

The department should strengthen this section by developing detailed SMART objectives specific to this proposal, including a time specific element for when the objectives would be achieved.

Identification of options

Identification of the ‘long-list’ of options

The department presents a longlist of options including a non-regulatory approach (issuing guidance) and the preferred regulatory option (new enabling powers). The options clearly link to the problem - the need for permanent powers to update slots regulations, rather than continuing to rely on temporary solutions. T

he OA should be strengthened by considering additional regulatory options, such as more narrowly defined or targeted powers focused on specific aspects of slot regulation. The OA does not discuss explicitly whether the options generation process involved engagement with stakeholders, which would strengthen the justification for the options identified. More information on industry views regarding the different options would enhance the assessment.

Consideration of alternative options to regulation

The department has identified issuing guidance as the primary alternative to regulation. The OA provides a clear explanation of what this alternative would involve - providing clarifications and non-binding interpretations of existing legislation - and acknowledges that guidance might be helpful in situations where there are grey areas not explicitly covered in slot regulations.

The OA could benefit from more detailed discussion of why this non-regulatory option would not be sufficient to address the identified problem. For example, it could explore specific scenarios where binding regulations would be necessary and guidance would be inadequate, perhaps drawing on examples from the international context or past experiences.

Justification for the short-listed options

The department has applied a version of the Green Book’s Options Framework Filter to assess the longlisted options, and discount several. The OA includes a clear table that evaluates options against 2 SMART objectives and 2 critical success factors. This structured approach provides transparency in the assessment process.

Small and micro businesses assessment

The OA has a good summary of the landscape, reviewing all the businesses who might be directly or indirectly affected by secondary powers. The OA explains that only one small business might be affected, a slot operator, and businesses will be consulted about related secondary legislation.

Justification for preferred way forward

Identifying impacts and scale

The department’s preferred option is to take forward new enabling powers through primary legislation. As the proposal is for enabling powers only, there are minimal direct costs or benefits from the government having these powers. Direct potential costs and benefits to business will arise through implementation of policies using these powers, and such policies will require secondary legislation and impact assessments quantifying the impacts.

To illustrate the potential scale of future interventions, the department has drawn on 2 recent changes to the Slots Regulations that were enabled by the REUL Act powers. The larger change had an estimated net present social value (NPSV) of £279 million (in 2019 prices).

Counterfactual and baseline

The OA notes quantification would require a defined counterfactual to estimate the detriment avoided by having enabling powers. Such an analysis depends on the specifics of policy proposals that will be taken forward in related secondary legislation.

The OA could benefit from illustrating trends in slot allocation practices across UK airports to demonstrate how the baseline has evolved over time, particularly in comparison with international practices and the EU’s regulatory approach.

Evidence and data

The OA relies primarily on qualitative assessment for this enabling-powers proposal, noting there are minimal costs or benefits from the government having these powers. To illustrate the potential application of these powers, the OA references recent changes to slot regulations enabled by the REUL Act powers. This approach provides useful context for understanding how the proposed enabling powers might be used.

The OA could be strengthened by providing more detailed data on:

• volume of slot transactions or allocations at coordinated airports in the UK
• comparative data on how slot regulation frameworks operate in other major aviation markets
• consultation with stakeholders about the need for more flexible regulatory powers

Additional quantitative evidence, such as historical data on slot utilisation rates and the economic impacts of previous regulatory updates, would support the case for enabling powers.

Uncertainty and risk

The OA identifies key risks of maintaining the status quo, including:

• UK businesses operating under outdated rules potentially losing competitive advantage
• inefficient or suboptimal slot allocation due to outdated regulation
• cost of divergence to businesses, for example airlines having to adjust operations to comply with different rules
• reputational damage and loss of credibility of the UK as a leader in global aviation

Selection of the preferred option

The department has selected primary powers as the preferred option based on its ability to meet all objectives and critical success factors. While issuing guidance would provide the ability to seek input from industry before implementation of future changes, it would not provide the necessary legislative framework to ensure that laws can be updated as needed. The preferred option provides a solution that puts the UK Government’s powers on par with those available to the EU, allowing for timely responses to changing circumstances in the aviation industry.

The department uses critical success factors to narrow the longlist and shortlist. Critical success factors should be used for the longlist. To narrow the shortlist other criteria are used, and the department should consult the Green Book on this process, to improve this assessment and its process more generally for assessments.

As an enabling powers bill would be used for the proposals, the department notes that specific impacts will be assessed through related secondary legislation. This approach is reasonable and proportionate, allowing for targeted impact assessments when specific policy changes are proposed using the powers.

Regulatory scorecard

Overall impact on total welfare

The primary legislation proposed is not expected to have direct impacts on social welfare as the powers are enabling.

Impacts on business and households

Direct impacts are not expected due to the enabling nature of the powers in the primary legislation. Specific impacts of policies introduced via secondary legislation will be assessed at a later stage.

Business environment

The primary legislation would provide powers that can be used to enable benefits of new airport capacity. These benefits extend into the wider economy through new job creation, improved connectivity, increased passenger throughput and enhanced investor confidence.

Trade and investment

The OA notes that slot coordination is inherently international. The proposals would support the UK’s ability to maintain alignment with international best practice. Maintaining international alignment can support negotiation of aviation agreements. It can also reinforce the UK’s influence in global aviation forums.

Natural capital and decarbonisation

The proposed primary legislation would not be expected to have direct effects on natural capital or decarbonisation goals. However, by enabling the government to update slot regulations more efficiently, the department notes it may support environmental goals through related secondary legislation. For example, alleviation from slot usage rules has successfully reduced occurrence of environmentally damaging ghost flights.

Monitoring and evaluation

While the department notes that detailed plans are expected in secondary legislation, it should still consider an overall plan for the proposed primary legislation. The OA does not provide sufficient detail on how the impact of the enabling powers would be monitored and evaluated. There is no indication of how the department would determine whether the enabling powers would still be required, or if the same objectives could be achieved differently in the future.