ACI World urges regulators to modernise

ACI World has intensified its campaign to reform what it calls an outdated global airport slot system. The airport association released a white paper today urging regulators to engage with the industry and modernise the allocation framework before a capacity crisis escalates further.

According to ACI World Director General Justin Erbacci, the industry is trying to run a 2026 aviation sector on a 1970s operating system. He states that inflexible rules are preventing adaptation to modern passenger demands, competitive fares, and resilient network building. The foundational regulatory framework for slot allocation has not kept pace with aviation's dynamic growth.

The scale of the capacity challenge

The pressure on airport capacity is accelerating. The number of the world's most congested, slot-restricted airports has surged by over 25% in the last decade alone. Global passenger traffic is projected to nearly double by the mid-2040s. ACI World notes that a small number of airports carry most global air traffic.

Fewer than 10% of the world's airports handle nearly two-thirds of all passengers. Also, 85.5% of the busiest airports, those serving more than 40 million passengers annually, are already operating at or near full capacity. The white paper argues that decisions about this scarce capacity are a matter of public interest, yet the current system offers little visibility into how allocation decisions are made.

How the current system limits competition

The existing slot allocation guidelines heavily prioritise historical patterns and incumbent airlines. ACI World contends this makes it difficult for the market to evolve, limiting competition and consumer choice while reducing connectivity quality. Historic access rights accumulate over time and are rarely released.

At the 50 most congested airports globally, the four largest airlines account for 67% of flights. The association believes the system's lack of adaptability challenges its ability to respond to shifting passenger demands or economic needs.

Proposals for a modernised framework

ACI World's white paper, titled Airport Slot Policy, Rethinking Airport Access in a Capacity-Constrained World, outlines the need for a transparent, future-ready system. A modernised framework should provide greater clarity on who requests airport access, who receives it, and why. This would allow airports, airlines, and policymakers to evaluate decisions and ensure infrastructure is used efficiently for the public interest.

The association believes a new framework would make the system more adaptable, allowing scarce capacity to respond to how aviation and its communities develop. Erbacci has called on airline representatives and legacy industry bodies to move past historical resistance and join the effort. He emphasises that airports are ready to do the work but cannot build the future alone. The goal is to design a system that unlocks operational efficiency, build healthy competition, and delivers the routes required by the 21st-century global economy.