Reading an airline

An airline produces a seat mile. It cannot be stored, it expires when the door closes, and the cost of producing it was committed when the schedule was published. Which is why the whole industry reports in cents per unit of it.

Three revenue measures, and why they differ

Yield is revenue per passenger mile actually flown. Passenger revenue per available seat mile is revenue per seat mile offered, whether or not somebody sat in it. Total revenue per available seat mile adds everything else the airline sells.

The gap between the first two is the load factor. Yield rose from 20.68 to 20.74 cents in 2025 while passenger revenue per available seat mile fell from 17.65 to 17.37, because the load factor fell from 85 percent to 84 percent. The airline charged slightly more per mile flown and sold a slightly smaller share of what it produced.

That is the distinction the industry's vocabulary exists to preserve, and it is the one a single revenue growth figure destroys.

The two numbers that are the business

Total revenue per available seat mile was 21.26 cents and cost per available seat mile was 19.31 cents. The difference is 1.95 cents.

Multiply by 298,045 million available seat miles and the two measures imply total revenue of about 63,364 million dollars, total operating cost of about 57,552 million, and a difference of about 5,812 million.

Which means a one percent error in either per-unit figure is worth roughly 600 million dollars, or about a tenth of the gap between them. There is no other industry in this course where the entire result sits inside two decimal places of two numbers quoted in cents.

Fuel, the input nobody sets

The airline consumed 4,269 million gallons in 2025 against 4,114 million in 2024, at an average price of 2.30 dollars a gallon against 2.57. That is about 9,819 million dollars of fuel, or roughly 3.29 cents per available seat mile, about a sixth of the 19.31 cent cost.

Volume rose because capacity rose. The price fell because the price of jet fuel fell, which nobody in the company decided. A model of an airline therefore needs the fuel price as its own explicit assumption, not as a percentage of revenue, because it is the one line whose driver sits entirely outside the business.

The three disclosures that matter

Capacity and load factor together, because a rising revenue figure produced by adding capacity at a lower load factor is a different fact from the same figure produced by filling the aircraft. Fuel gallons and average price separately, so the volume and price effects can be told apart. And the fleet commitments in the notes, because capacity three years out is already contracted.

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