The formulas
- ASK = seats available × kilometres flown, summed over all flights
- RPK = paying passengers × kilometres flown, summed over all flights
- Load factor = RPK ÷ ASK
Example
| Flight | Seats | Paying passengers | Distance | ASK | RPK |
|---|---|---|---|---|---|
| A | 180 | 150 | 1,000 km | 180,000 | 150,000 |
| B | 300 | 270 | 5,000 km | 1,500,000 | 1,350,000 |
| Total | 1,680,000 | 1,500,000 |
Load factor across both flights: 1,500,000 ÷ 1,680,000 ≈ 89.3%.
Why they matter
ASK and RPK are the common units of airline economics. Capacity growth is reported in ASK, traffic growth in RPK, and revenue and cost are compared per ASK (RASK and CASK) so that airlines and routes of different sizes and lengths can be compared. Cargo has equivalents: ATK (available tonne kilometres) and RTK (revenue tonne kilometres).
ASK and RPK in Wireum Insights
Wireum Insights reports ASK/ASM and RPK/RPM by route and period, with load factor and route and station metrics, as part of its capacity and traffic view.