Technical Note: Direct Operating Costs 

On the Cost of One Flight Hour

FLIGHT-X can calculate the Direct Operating Costs (DOC) of the airplane, on the basis of over 40+ cost parameters, which are established in a configuration file that can be found in the airplane model sub-folder. The parameters that are considered in the DOC analysis include:

Currency, aircraft cost, current fuel price, fuel price inflation, fuel shock price and corresponding fiscal year, insurance costs, spare parts on category I (airframe, landing gear, tyres), spare parts on category II (engines, APU, lubricants), spare parts on category III (avionics, systems, modernisation, refurbishment); aircraft life-time, depreciation, financing, interest rates, mortgage life-time, crew costs on category I (pilots and co-pilots), crew costs on category II (flight attendants), off-station costs (overnight out of position); labour rates on category I (power plant), labour rates on category II (in house), labour rates on category III (outsourced); flight services costs, ground services costs, average stage length. FLIGHT-X estimates the following:

  • Number of pilots required for operating the aircraft year round.
  • Number of flight attendants required for operating the aircraft year round.
  • Number of cycles and airplane utilisation.
  • Off-station crew nights.
  • Fuel burn per cycle.
  • Block time per cycle.
  • Cost per available seat mile (CASM).
  • DOC/n-mile flown.
  • Ticket price required to break even, with and without commercial cargo.

FLIGHT-X accounts for the following externalities:

  • Increase in fuel consumption due to deterioration and engine wash.
  • Any other eventuality, which can be included in a mission scenario.

The figure below shows the estimated ticket price required to break even for a hypothetic aircraft costing 27 million dollars, acquired with internal financing (20%) and external financing (80%) over a period of 10 years, assuming that the aircraft operates as a commuter over stage lengths of 200 n-miles without significant commercial freight. A shock oil price of 25% is forecast on year 2. A risk analysis is possible by using stochastic data of the parameters. Figure 1 shows a typical result.

Note that carrying extra fuel weight will cause additional emissions on the outbound flight, and this option has been publicly discouraged in the recent past.


  • Working hours/week      =  35 (flight attendants)
  • Flight hours/month         =  80  (pilots)
  • Total pilots                       =   8
  • Total flight assistants     =  16
  • Airplane utilisation         =  5,232 [hours/year]
  • Cycles per day                =    8
  • Effective cycles               =   2,880 (input data superseded)
  • Turn-around time           =  30 [minutes]
  • Off-station crew nights =    0 times/year
  • Inflation                           =    2% applied to all items except fuel


  1. Departure at  7:00  ; Arrival at    8:20
  2. Departure at  8:50   ; Arrival at  10:10
  3. Departure at 10:39  ; Arrival at 11:58
  4. Departure at 12:28  ; Arrival at 13:47
  5. Departure at 15:17  ; Arrival at 16:36
  6. Departure at 17:05  ; Arrival at 18:25
  7. Departure at 18:55  ; Arrival at 20:14
  8. Departure at 20:44  ; Arrival at 22:05  (back at origin airport)
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