Global scheduled seat capacity reached 137.1 million in the week to 21 September 2026 — 1.6% above the same week a year earlier. On that measure, aviation looks close to normal. The industry's cost base tells the opposite story.

Jet fuel climbed back towards USD200/bbl in September 2026. The average price hit USD194.90/bbl in the week to 18 September, 116.4% higher than a year earlier, according to the latest market data. The fuel crack spread — the refining margin embedded in jet prices — was up 219.2% year on year. That spread matters as much as the crude price itself: it means airlines absorb a refining bottleneck on top of the oil shock, and hedging crude alone does not protect against it.

The result is a market caught between resilient demand and deteriorating economics, as CAPA - Centre for Aviation's latest Airline Leader Briefing sets out. Outside the Middle East, capacity and traffic are broadly reverting to familiar seasonal patterns. International tourist arrivals were broadly flat in the first half of 2026. Large aircraft deliveries are finally accelerating after years of supply-chain constraint, easing one structural pressure on fleet capacity just as fuel intensifies another on unit costs.

Several markets continue to grow. Consumers, though, are becoming more price-conscious — a behavioural shift that limits how much of the fuel spike airlines can pass through in fares before demand responds. The oil market itself has become increasingly difficult to forecast, which complicates hedging decisions and fleet-planning assumptions alike.

The financial evidence is already visible. Airline financial results are weakening even as operations hold up. The divergence between what airlines fly and what they earn is the defining feature of this phase of the cycle: aircraft are full, schedules are intact, and balance sheets are bleeding.

The central question has shifted. It is no longer whether aviation can operate through the crisis — it demonstrably can. Capacity is up year on year, seasonal patterns have reasserted themselves, and deliveries are accelerating. The question now is how much financial damage is accumulating beneath that operational resilience, and whether airlines enter 2027 with materially weaker balance sheets just as the next phase of the cycle begins.

For network planners, the arithmetic is straightforward. A fuel price of roughly USD195/bbl against broadly flat international demand compresses margins faster than capacity discipline alone can restore them. For lessors and OEMs, accelerating wide-body deliveries land in a market where operators may struggle to absorb the additional seat capacity profitably. For MRO providers, an ageing active fleet flown through a cost squeeze defers some retirement decisions even as new types arrive.

The week-to-week data frames the tension precisely: 137.1 million seats supplied, 1.6% growth delivered, and a fuel bill more than doubling. Whether 2027 opens with an industry that has traded balance-sheet strength for operational continuity is the question the next two quarters of results will answer.