The airline business is very particular when it comes to types of revenue and cost and it also uses specific metrics.

**Passenger yield (Yield)**

Represents the average revenue generated per passenger and kilometer (i.e. revenue per RPK). This is calculated by dividing the total revenue generated by passengers (e.g. EUR) by RPK and it is normally expressed in EUR or USD cents per RPK.

This metric is used to measure earnings per passenger per kilometer and can be used by an airline to compare different markets or financial periods. However, this metric does not take into account passenger load factor, which could be solved by using total capacity (RASK).

**Revenue per available seat kilometer (RASK) **

This is one of the most important metrics when referring to the revenue of the airline, often called unit revenue. Revenue per available seat kilometer (RASK) is calculated by dividing total passenger revenue by total capacity (ASK). This is normally expressed in EUR cents per seat kilometer (ASK).

RASK is the metric that airline revenue managers aim to maximize and will be an important metric comparing the performance of one airline between two different financial periods.

**Cost per available seat kilometer (CASK) **

The same approach used with RASK to calculate unit revenue is used with CASK (Cost per available seat kilometer) to calculate unit cost. CASK is calculated by dividing total operating cost by total capacity (ASK). This is normally expressed in EUR cents per seat kilometer (ASK).

CASK is the metric that airlines try to minimize, in order to maximize profit. However, in some cases airlines have very limited influence on certain costs and consequently use alternative metrics.

**Ex-Fuel cost per available seat kilometer (Ex-Fuel CASK) **

The cost of fuel for an airline can vary from 20 to 40% of total operating cost and will depend on the oil price, which the airline has very limited influence on.** **Airlines therefore often exclude the fuel cost when measuring CASK (Ex-Fuel CASK)**. **This metric is calculated by subtracting fuel cost from total cost** **and dividing this by total number of available seats (ASK).

**Profit per ASK**

Following the calculation of unit revenue per seat (RASK) and unit cost per seat (CASK), the unit profit per seat is calculated by subtracting RASK minus CASK.

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