Aviation Finance & Capacity Planning
Airline RASM, CASM & Break-Even Load Factor Formula
Calculate Available Seat Miles (ASM), Revenue Passenger Miles (RPM), Passenger Yield, RASM, CASM, and Break-Even Load Factor BELF = CASM / Yield.
Link aircraft capacity (ASM) and passenger traffic (RPM) via RASM = Load_Factor * Yield!
Airline network planners measure supply in Available Seat Miles ASM = Seats * Stage_Miles, demand in Revenue Passenger Miles RPM = Paid_Passengers * Stage_Miles (Load Factor LF = RPM / ASM), pricing power in Passenger Yield = Passenger_Revenue / RPM ($ per passenger-mile), unit revenue in RASM = Total_Operating_Revenue / ASM (for passenger-only PRASM = LF * Yield), and unit cost in CASM = Total_Operating_Expense / ASM! Setting Passenger Revenue LF * ASM * Yield + Ancillary_Cargo_Rev equal to Total Operating Cost CASM * ASM gives Passenger-Only Break-Even Load Factor BELF = CASM / Yield (or Net-of-Ancillary Break-Even Load Factor (CASM - Ancillary_RASM) / Yield)!
Verify on a 180-seat narrowbody flying Stage_Length = 1,000 miles (B2 * B3 -> ASM = 180,000 seat-miles) carrying Paid_Passengers = 153 (B4 -> RPM = 153,000, Load Factor = 0.8500 = 85.0%), Passenger_Ticket_Revenue = 27,540 (B5), and Flight_Operating_Cost = 23,400 (B6): Passenger Yield is 27,540 / 153,000 = 0.1800 $/RPM (18.00 cents/mile); PRASM is 27,540 / 180,000 = 0.1530 $/ASM (= 0.85 * 0.18); CASM is 23,400 / 180,000 = 0.1300 $/ASM (13.00 cents/ASM); and Break-Even Load Factor is 0.1300 / 0.1800 = 0.7222 (72.22% = 130 passengers needed to break even, giving +12.78 percentage points of Load-Factor cushion)!
| Aviation Economics KPI (180 Seats, 1,000 mi, 153 Pax) | Formula | Verified Output |
|---|---|---|
| Passenger Yield ($ / RPM) | Ticket_Rev / (Pax * Miles) | 0.1800 ($0.18 / pax-mile) |
| Passenger RASM ($ / ASM) | Ticket_Rev / (Seats * Miles) | 0.1530 ($0.153 / seat-mile) |
| Unit Operating Cost CASM ($ / ASM) | Flight_Cost / (Seats * Miles) | 0.1300 ($0.130 / seat-mile) |
| Break-Even Load Factor (BELF) | CASM / Yield | 0.7222 (72.22% vs 85.00% Actual) |
Unit Revenue RASM & Unit Cost CASM Formula
Validate Seats > 0, Miles > 0, 0 < Pax <= Seats, Ticket_Rev > 0, and Cost >= 0.
=LET(st_n, B2, ml_d, B3, px_n, B4, rv_t, B5, IF(OR(st_n <= 0, ml_d <= 0, px_n < 0, px_n > st_n, rv_t < 0), "Invalid Flight Input", ROUND(rv_t / (st_n * ml_d), 4)))Exact Break-Even Load Factor BELF = CASM / Yield Formula
Simplifying (Cost / ASM) / (Rev / RPM) cancels Stage_Miles cleanly to (Cost / Seats) / (Rev / Pax) — cost per seat divided by average fare!
=LET(st_n, B2, ml_d, B3, px_n, B4, rv_t, B5, cs_f, B6, IF(OR(st_n <= 0, ml_d <= 0, px_n <= 0, px_n > st_n, rv_t <= 0, cs_f < 0), "Invalid Flight Input", LET(casm_u, cs_f / (st_n * ml_d), yld_u, rv_t / (px_n * ml_d), ROUND(casm_u / yld_u, 4))))Try the example
Use the original values or change them to test your understanding.