US Gateway Fragmentation Reshapes Airline Fleet Decisions

There are changes occurring among the Top Ten US gateway airports regarding international flights. We see a distinct fragmentation. But this isn't necessarily a bad thing. Change can be positive. However, fragmentation does impact how airlines serving these routes optimize their aircraft. And that, as you imagine, is a really big thing. IATA published this report on connectivity last year. The Chart [caption id="attachment_195526" align="aligncenter" width="640"] DHS I-92; AirInsight[/caption] In network analysis, fragmentation means traffic is spreading out, causing core routes to lose market share. Defragmentation (or consolidation) would mean traffic concentrates more heavily on the top routes, causing the lines to climb. The blue arrow points toward rising fragmentation. The Core Trend: Fragmentation Across Major Hubs Most legacy and connecting hubs are seeing a steady, multi-year decline in the concentration of their top 10 routes. DFW (Light Purple): This is the most dramatic example. In 2022, its top 10 routes captured over 52% of its total international passenger volume. By 2026, that share collapsed down to around 41.5%. ATL (Dark Grey), ORD (Dark Green), and IAH (Olive): All follow a similar, tight downward slope. Their top 10 routes used to command 47%–50% of their traffic and are now hovering between 40%–45%. For mega-hubs like DFW, ATL, and ORD, the network is expanding into secondary markets. They are adding new, lower-frequency destinations, which naturally dilutes the share held by their traditional top 10 "trunk" routes. The Notable Exception: SFO Consolidation SFO (Dark Blue - Top Right): SFO completely bucks the trend. After holding flat at nearly 50% for years, its top 10 route share spiked sharply between 2025 and 2026, exceeding 52%. SFO is experiencing consolidation. This usually happens when an airport's recovery or growth is heavily driven by a few massive, high-frequency trunk lines (likely core transpacific or major European trunk routes roaring back or expanding), while secondary regional routes aren't keeping pace. The Flat Baselines: JFK, MIA, and EWR JFK (Cyan), MIA (Medium Blue), and EWR (Medium Purple): These airports sit much lower on the chart (in the 33%–37% range) and have remained remarkably stable. These gateways are already highly fragmented and diverse. Because they inherently serve a massive, sprawling array of international destinations, their top 10 routes never commanded 50% to begin with, and their network footprint is holding steady. So What? US airlines with hubs at these airports have to monitor flows closely because getting the gauge right is critical for economic success. If an airline gets that wrong, the error can be expensive. Fortunately, booking data provides the necessary guidance. DFW's changing profile is a good example. It has two primary markets: long-haul and short-haul. The long flights operate with around 250 people per flight. So 787-9 and A350-900 are ideal for these routes. Not a 777-9 or A350-1000. Paris (CDG) is softening, and, for example, American Airlines might be better placed to deploy 787-8s. But Incheon (ICN) is growing fast, and American's 787-9s might not be enough. [caption id="attachment_195527" align="aligncenter" width="640"] DHS I 92; AirInsight[/caption] For Foreign Flag carriers, the fragmenting US market is excellent news. Fragmentation means fortress hubs are being avoided. The following chart illustrates this well. California's two big airports appear stable. But the rest don't look as robust. [caption id="attachment_195528" align="aligncenter" width="640"] DHS I-92; AirInsight[/caption] The London-to-US route is one of the thickest routes. Here's what traffic between Heathrow and the US looks like. Miami looks robust. The rest looks anemic. [caption id="attachment_195529" align="aligncenter" width="640"] DHS I-92; AirInsight[/caption] Here's another piece of evidence. The margin is thin, but it certainly looks like US fortress hubs are not what they were even a few years ago. [caption id="attachment_195530" align="aligncenter" width="668"] DHS I-92; AirInsight[/caption] For a British airline, for example, operating A321 (or any MOM) might offer the right gauge for many markets. As US traffic continues to fragment, smaller, longer-range aircraft will enable even greater fragmentation. This is the old 787 vs A380 argument playing out one tier down. Bottom Line Fragmentation isn't a crisis — it's a signal. Airlines that read it correctly will right-size their gauge before market forces do.

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