Mexico City International Airport Returns Flight Slots to US Carriers: A Comprehensive Analysis of Aviation Diplomacy and Market Dynamics

In August 2025, Mexico announced the restoration of flight slots at Mexico City International Airport (MEX) to United States carriers,a significant reversal of earlier policies that had favored Mexican Airlines. This move comes after years of bilateral tension over slot allocations, airport capacity, and adherence to the 2015 US-Mexico Open Skies Agreement. The decision is set to impact major US airlines, notably United Airlines, and may signal a de-escalation in an ongoing dispute that has threatened airline partnerships, disrupted cargo operations, and created uncertainty in one of the world’s busiest international aviation corridors.

The restoration of slots is not merely a technical administrative change; it is a diplomatic gesture with far-reaching implications for trade, airline operations, and the regulatory frameworks governing cross-border air travel. For the United States Department of Transportation (DOT) and US carriers, this policy shift addresses long-standing concerns about market access and Mexico’s compliance with international aviation agreements. For Mexico, it is both a response to growing international pressure and an attempt to stabilize a critical sector of its economy.

This article examines the historical context, recent developments, financial impacts, and regulatory implications of Mexico’s decision, providing a balanced analysis of its significance for the Manufacturing industry and broader US-Mexico relations.

Historical Context and the Evolution of US-Mexico Aviation Relations

The modern framework for US-Mexico aviation was established with the Air Transport Agreement signed in December 2015 and implemented in August 2016. This “open skies” agreement eliminated most restrictions on routes, frequencies, and the number of airlines operating between the two countries. Airlines from both nations could fly between any city pair, and Cargo-Aircraft carriers gained expanded rights, allowing for increased flexibility and competition.

Mexico City International Airports (MEX), officially Benito Juárez International, has historically been the central hub for US-Mexico air traffic. The airport handles a significant share of both countries’ international passenger flows, but its critical role has also exposed it to severe congestion and operational challenges. By 2018, MEX was handling almost 48 million passengers annually, far exceeding its designed capacity of 32 million, making slot allocation a contentious and highly valuable process.

Efforts to address congestion have included both expansions of existing infrastructure and attempts to build new airports. A major new airport project at Texcoco was cancelled in 2018, replaced by the construction of Felipe Ángeles International Airport at Santa Lucía, which opened in 2022. However, MEX remains the primary gateway, and its slot system continues to be the focal point of bilateral aviation disputes.

The 2022 Slot Reallocation and Its Consequences

In 2022, Mexican authorities reallocated a number of slots at MEX from US to Mexican airlines, a move that sparked immediate concern and protest from US carriers and regulators. United Airlines, for example, saw its access curtailed, affecting its ability to serve key routes from US hubs such as Chicago, Houston, Newark, Washington Dulles, and San Francisco. This reallocation was part of a broader trend under President Andrés Manuel López Obrador’s administration, which had already shifted airport policy through the cancellation of large-scale infrastructure projects and increased state control over aviation assets.

Slot restrictions at MEX were originally implemented in response to persistent overcapacity. Since 2014, authorities had capped operations at 61 per hour, later reducing this to 52 and then 43 by October 2023. These moves were justified by Mexican officials as necessary for safety and congestion management, but US regulators and airlines argued that the process lacked transparency and discriminated against foreign carriers in violation of the Open Skies Agreement.

The 2022 reallocation forced US airlines to reduce frequencies or seek alternative arrangements, disrupting established networks and limiting the ability of US carriers to compete effectively in the lucrative Mexico City market. For airlines like United, which had previously secured additional slots for routes such as San Francisco-Mexico City, the uncertainty over long-term access hindered strategic planning and investment.

“The unreliable and nontransparent slot administration practices that reduced capacity at MEX have created potential harmful impacts of antitrust immunity in this environment, with specific emphasis on the lack of entry or the possibility of entry in the Mexico City market.”, US Department of Transportation

Escalation of Bilateral Disputes and Regulatory Actions

By 2023, the dispute had escalated. Mexico implemented new slot restrictions and required all-cargo operations to relocate from MEX to Felipe Ángeles International Airport, giving US carriers and other international operators less than four months to adapt. This forced relocation affected a wide range of industries reliant on air freight, including automotive, medical devices, and pharmaceuticals, and raised operational costs for airlines and logistics providers.

The US Department of Transportation responded with a series of enforcement actions in July 2025, requiring Mexican airlines to submit detailed operational data and seek prior approval for charter flights. The DOT also threatened to terminate the antitrust immunity of the Delta-Aeromexico joint venture, a move that could disrupt one of the largest transborder airline partnerships and affect thousands of US jobs.

Industry groups, including the International Air Transport Association (IATA), criticized Mexico’s approach, arguing that capacity changes and slot allocations should be based on transparent, expert-driven methodologies aligned with global standards. IATA noted that the lack of consistent Regulations and monitoring at MEX created systemic distortions, including higher fares, limited supply, and reduced competition.

Recent Developments and Implications of Slot Restoration

The August 2025 decision to return slots to US carriers came after intense diplomatic and regulatory pressure from the United States. United Airlines, in its filing to the DOT, confirmed that Mexican officials had notified several US carriers of the slot restoration, reversing the 2022 allocation to Mexican airlines. This move is widely seen as a response to the threat of further US enforcement actions and the potential loss of Mexican carriers’ access to the US market.

The immediate beneficiaries include United Airlines and other major US carriers, which can now plan for expanded year-round service at MEX. The restored slots are expected to enhance connectivity for business and leisure travelers and may rebalance competition in the US-Mexico market, where the Delta-Aeromexico joint venture had previously dominated with over 21% of two-way seat capacity.

However, the restoration of slots does not resolve all underlying issues. Regulatory uncertainty remains, particularly regarding the future of airline partnerships and the long-term stability of slot allocation policies. The DOT’s ongoing review of the Delta-Aeromexico joint venture and the suspension of other proposed partnerships, such as Allegiant and VivaAerobus, highlight the fragility of current arrangements.

“Capacity changes must be made with the greatest technical and operational rigor, based on expert studies and analysis.”, Peter Cerdá, IATA Regional Vice President for Americas

Financial and Market Impact

The economic stakes in the US-Mexico aviation market are substantial. Aviation activities contribute an estimated $83 billion to Mexico’s economy and nearly 5% of its GDP. The restoration of slots allows US carriers to better compete for a share of this market, particularly as passenger demand continues to recover and grow.

For United Airlines, the ability to increase frequencies and restore previously cut routes at MEX is expected to improve competitiveness, especially against Aeromexico and other Mexican carriers. The broader competitive landscape may also shift, with American Airlines and other US carriers able to leverage restored access to challenge the dominance of the Delta-Aeromexico partnership.

Yet, the financial benefits are tempered by ongoing risks. The potential termination of the Delta-Aeromexico joint venture, for example, could impact $800 million in economic value and threaten 4,000 US jobs, according to industry estimates. The aerospace supply chain, including aircraft Manufacturers like Boeing, faces uncertainty as airlines adjust their long-term fleet and network strategies in response to regulatory changes.

Regulatory and Policy Considerations

Mexico’s slot restoration occurs within a complex regulatory environment shaped by both domestic law and international agreements. The 2015 Air Transport Agreement mandates non-discriminatory access and transparency in slot allocation, principles that US officials argue were violated by Mexico’s previous actions. The Mexican Federal Economic Competition Commission (COFECE) has also highlighted deficiencies in slot management at MEX, calling for improved transparency and accountability.

The DOT’s recent enforcement actions reflect a more assertive US approach to ensuring compliance with bilateral agreements. Requirements for operational data, charter flight approvals, and the threat of market access restrictions are intended to pressure Mexico into aligning its aviation policies with international norms. These measures also signal to other countries the importance the US places on open and fair aviation markets.

Looking forward, the success of the slot restoration will depend on sustained reforms to Mexico’s slot allocation system and ongoing dialogue between US and Mexican authorities. Effective implementation of COFECE’s recommendations and alignment with IATA’s Worldwide Slot Guidelines could help reduce future disputes and support stable market growth.

Conclusion

Mexico’s decision to return flight slots at Mexico City International Airport to US carriers is a pivotal step in resolving a complex and protracted dispute over aviation market access. The move is likely to yield immediate operational benefits for US airlines and may help rebalance competition in the transborder market. However, it also underscores the continuing challenges of managing scarce airport capacity and the importance of transparent, non-discriminatory regulatory frameworks.

The broader implications of this policy shift extend beyond aviation, touching on trade, economic growth, and diplomatic relations between the US and Mexico. The resolution of the slot dispute offers a potential model for addressing similar challenges in other congested international markets but also highlights the need for ongoing vigilance and cooperation to ensure that open skies agreements deliver on their promise of fair competition and expanded connectivity.

FAQ

Question: Why did Mexico reallocate slots at Mexico City International Airport in 2022?

Answer: The reallocation was part of broader capacity management efforts at MEX, but US officials and airlines argued that the process lacked transparency and unfairly disadvantaged foreign carriers, violating the 2015 Open Skies Agreement.

Question: What prompted Mexico to restore slots to US carriers in 2025?

Answer: The restoration followed increased diplomatic and regulatory pressure from the US, including threats of enforcement actions and potential restrictions on Mexican airlines’ access to the US market.

Question: How does slot allocation at Mexico City International Airport affect airline competition?

Answer: Slot allocation determines which airlines can operate at the airport and how frequently, directly impacting competition, route availability, and market share for both US and Mexican carriers.

Question: What is the status of the Delta-Aeromexico joint venture?

Answer: As of mid-2025, the partnership is under review by the US DOT, with its future uncertain due to ongoing regulatory disputes and potential termination of antitrust immunity.

Sources

ch-aviation, US Department of Transportation, IATA, Reuters