Field notes
59 field notes, for the charts featured on the question pages. Every chart on the site has a note; these are the featured ones.
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Maintenance cost per flight hour is about 4 times as high for a fleet averaging 35 years old as for one averaging 1 year
Older fleets cost more to maintain per flight hour, on one age slope for every aircraft class. At any age the wide-body curve sits well above the narrow-body one and the regional curve a little below it.
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At assumed GDP growth, US airlines would need about 59% more seat-miles in 2044 than they flew in 2024
In this what-if, each line grows today's seat-miles at an assumed rate of economic growth times the income elasticity. Seat-miles measure the capacity airlines fly, not the number of aircraft they need.
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By fleet age 16 the odds tip from growing the fleet to shrinking it
The older a fleet of one aircraft type, the less often it grows and the more often it shrinks, though at most ages it is likeliest to stay as it is. This describes whole fleets, not one aircraft's chance of retiring.
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Narrow-bodies leave service at a median of 25 years of age
Here, regional aircraft leave US service youngest, wide-bodies oldest and narrow-bodies in between. Every median is later if only aircraft reported as withdrawn count, so the result depends on how an exit is counted.
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Top 15 aircraft types (2024)
One Boeing single-aisle model is the most numerous active type by a wide margin. Boeing's and Airbus's single-aisle families fill most of the ranking; regional jets and two older Boeing types make up the rest.
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Fleet utilisation by category
Daily flying hours per aircraft have held steady for big jets but fallen by roughly a third for regional aircraft over the past decade and a half.
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The US stays the biggest single air-travel market through 2044; India grows fastest
Of the ten markets covered, India's projected passengers more than double over the coming two decades, far more than any other's. The United States stays the largest, though each market counts passengers its own way.
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The income model and the hub trend put 10-market traffic near 4.1 billion by 2044
The ten markets combined over the coming two decades, as the sum of the income model's projections and Singapore's time trend. Supply-side and network growth are left out, so this is not a full forecast.
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US flying grows slowly on income alone: about 1.34 billion passengers by 2044
This central projection counts only income and population growth and leaves out new routes, cheaper fares and airline expansion.
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US air freight: ton-mile share of all-cargo airlines vs airlines that also carry passengers
All-cargo airlines fly about two-fifths of US air freight ton-miles, a share that peaked in the first pandemic year. The split is by airline, not aircraft: a passenger airline's own freighters count on the other side.
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Long-haul routes are fewer, not thinner
The longer distance bands hold fewer routes, but passengers per route are broadly similar in every band, with the longer bands slightly ahead.
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India: passenger seasonality, 2013–2019 vs 2023–2025
Indian air travel peaks in December in both periods, and the seasonal swing is gentler than a decade ago. The quietest month has moved from February to July.
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Mexico: domestic vs international (indexed, 2006 Q1 = 100)
Mexican domestic air travel has more than tripled since the turn of the century while international more than doubled. Domestic pulled ahead in a burst before the financial crisis, and the two have grown alike since.
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Log passengers vs log GDP
Each dot is one quarter across three and a half decades. As the US economy grows, air travel grows with it, tightly and persistently.
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COVID recovery by route type
Compared quarter for quarter with the last pre-COVID year, routes between two hubs carry about the same traffic and the other two kinds more. Point-to-point routes recovered last and have led only in the latest year.
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A 10% longer flight costs about 3% more, so fares rise far more slowly than distance
Each dot is a route, sized by its passengers, and the line is the fit to the dots. Among short and medium routes, fares at a given distance still differ several-fold.
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Brazil: air freight (indexed)
Brazilian air freight has more than doubled since the turn of the century, ending close to its all-time peak.
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Country share of reporting European air passengers (2025)
Among the European countries in the data, Spain carries the largest share of passengers, ahead of Germany, Italy and France. The total covers the reporting countries only, so it is not the whole of Europe.
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Yield by carrier type
Passengers pay more per mile on legacy airlines than on low-cost airlines. The gap closed around the financial crisis, briefly reversed a few years later and has widened again since.
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Freight seasonality by decade
The fourth quarter is the freight peak and the first quarter the trough in every decade shown. The series counts freight and mail on all-cargo flights only.
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India: domestic route network size
India's domestic network roughly doubled in a decade in city pairs flown, and cities served rose by more than half. The chart counts routes and cities and does not show what drove the growth.
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Australian air travel grew 473% from 1985 to 2019 while GDP grew 184%
Australian air travel grows substantially faster than the economy, among the steepest responses of the ranked markets, but its long-run test passes only with the pandemic years in the sample.
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Industry cost vs revenue per available seat-mile
Airline revenues per seat-mile have generally stayed just above costs, so the industry's operating margin has been persistently thin.
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India: domestic passenger traffic (quarterly)
Indian domestic air travel has roughly tripled in a decade and a half, ending the sample at its all-time peak despite the COVID collapse.
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Air passenger traffic: selected European markets (indexed, first observed quarter = 100)
Poland's air traffic has grown more than tenfold, by far the most of these European markets, while France and Germany have grown the least. Each line starts from that country's first quarter in the data.
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Canada's non-US international traffic is 4% above 2019 while domestic remains 8% below
Canada's non-US international traffic has passed its pre-COVID level while domestic and US transborder flying still lag, leaving the total slightly short of it.
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COVID recovery by international region
Latin America is well above its pre-COVID level, while transpacific travel is still well short of its own and is the only region yet to recover.
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China: national passenger traffic (quarterly)
Chinese air passengers have grown more than fivefold in two decades, with the COVID collapse a deep but temporary interruption.
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China: domestic vs international route count
China's route expansion has been overwhelmingly domestic. International routes collapsed in the pandemic and have not returned to their pre-COVID count.