United Airlines disputes Delta's defense amid scrutiny over Aeromexico joint venture

Delta also referenced Lisbon Airport (LIS), suggesting that TAP Air Portugal’s control over slots benefits alliance partners like United. In response, United emphasized that cooperation at LIS is limited and not comparable in scale or structure to the Delta-Aeromexico partnership: "Delta’s claim—that the Department fails to treat similarly situated carriers alike—relies on the flawed premise that HND and LIS are “like” MEX, ignoring the nuanced ecosystems of bilateral compliance and negotiation histories that make them incomparable."

At issue are alleged violations of the US-Mexico bilateral agreement by Mexican authorities. In 2022, Mexico rescinded airport slots from multiple U.S. airlines at MEX without subsequent construction work taking place as initially cited for congestion relief. The forced move of cargo carriers from MEX further strained relations.

As a result, new requirements have been imposed on Mexican airlines flying into the U.S., such as obtaining prior DOT approval for large aircraft flights and submitting flight schedules in advance.

The DOT issued a Supplemental Show Cause Order (SCO) in July proposing revocation of antitrust immunity for the Delta–Aeromexico JV by October 2025. The U.S. Department of Justice has supported this move due to ongoing concerns about Mexican government policies affecting fair competition.

According to United, Mexican officials have indicated they will return confiscated slots to affected U.S. airlines—a position supported by American Airlines, which argued these changes would be fairer for both consumers and operators.

Delta maintains that ending its JV with Aeromexico will harm both consumers and airlines, calling recent government actions "unprecedented overreach." The partnership covers more than 20 routes with nearly two million annual seats involved. Delta has requested an extension beyond October 2025 until March 2026 as it seeks additional time before winding down cooperation with Aeromexico.

###