CASM

Cost per Available Seat Mile -- an airline's total operating expenses divided by its capacity (available seat miles), in cents. It answers "what did it cost to fly one seat one mile?" Airlines live on the spread between what each seat mile earns (RASM) and what it costs (CASM), so small CASM changes move profits a lot. Fuel is the biggest swing, which is why airlines also report a fuel-excluded version (CASM ex-Fuel). Total CASM runs higher for carriers with shorter average flights, and it includes everything in operating expense -- at Delta, for example, the cost of its refinery's sales to outside customers -- so read each airline's own reconciliation before comparing two carriers.

Related terms

Accounts Payable · Adjusted EBITDA · Adjusted EBITDA Ex-SBC · Administered-Only Members · ADR · ARPU

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