RASK and CASK are among the most useful measures of airline economics because they put revenue and cost against the capacity an airline produces. They are also easy to misuse: definitions, stage length, business mix and reporting periods differ across carriers. This hub connects the airline profiles where those disclosures can be checked in context.
Key unit-economics definitions
- RASK — revenue per available seat kilometre: revenue divided by ASKs, subject to the airline’s own revenue definition.
- CASK — cost per available seat kilometre: operating costs divided by ASKs.
- CASK ex-fuel: CASK excluding fuel, useful for tracking controllable or structural cost trends, but company definitions can differ.
- Yield: passenger revenue per revenue passenger kilometre (RPK). Yield is not the same as RASK because RASK also reflects load factor and, depending on the company, other revenue.
Airlines with useful unit-economics disclosure
These standardized profiles are the best starting points for airline unit-revenue and unit-cost analysis. The exact metric and period disclosed varies by carrier, so the source notes on each page should be read before making direct comparisons.
Why RASK and CASK comparisons can mislead
- Stage length: longer average sectors usually reduce cost per ASK even when the absolute cost of a flight is higher.
- Load factor: RASK can move even when yield is stable because more or fewer seats are filled.
- Ancillary revenue: carriers differ in how non-ticket revenue is included and disclosed.
- Network mix: long-haul, short-haul, connecting and point-to-point models are structurally different.
- Currency and fiscal periods: reported trends may cover different calendars and currencies.
- Company definitions: adjusted, ex-fuel and ex-ETS measures are not always calculated consistently.
Use unit economics with profitability and traffic
RASK and CASK are most useful when read together with load factor, yield, operating margin and fleet growth. A carrier can improve load factor while worsening profitability if fares or unit revenue fall faster than costs, and a higher CASK is not automatically negative if it accompanies stronger RASK.
Continue with the Airline Comparison tool, the Airline Operating Margins hub, the Airline Financial Results Database, or browse the full Airline Intelligence database.