Generating Cost Efficiency Charts: A Comparison between B737, A319 and A321

The intent of this paper is to calculate the cost efficiency for three aircraft namely B737-500, A319, and A320 for prescribed sectors. The cost efficiency is to be calculated using the flight data provided by an airline and the output was assessed for two possible flight scenarios. The cost efficiency charts would be useful for airlines and fleet planners in the discussion making, and in-depth rout analysis. The two routs considered here are Jeddah to Medina (JED to MED) and Jeddah to Riyadh (JED to RUH). All trips would be assumed as round trip flights. Table 1 shows the selected engine type for the study


Introduction
The intent of this paper is to calculate the cost efficiency for three aircraft namely B737-500, A319, and A320 for prescribed sectors. The cost efficiency is to be calculated using the flight data provided by an airline and the output was assessed for two possible flight scenarios. The cost efficiency charts would be useful for airlines and fleet planners in the discussion making, and in-depth rout analysis. The two routs considered here are Jeddah to Medina (JED to MED) and Jeddah to Riyadh (JED to RUH). All trips would be assumed as round trip flights. Table 1 shows the selected engine type for the study

Methodology
The first step in all scenarios was to determine the flight utilization. This was done by stating values for the time to climb and descend, and the associated climb and descent speed, along with various associated distances.
The take-off weight of each of the aircraft is calculated by the weight fraction method as identified in Figure 1, [1]. Since the empty weight was known for each aircraft, the total weight and fuel weight is easily determined.
The first step would be to calculate the payload weight Wpl from equation 1

40 Wpl number of passengers
The second step would be to calculate the fuel weight Wf from equation 2 Where M ff if the fuel fraction calculated, the fuel fraction ware calculated in each phase of flight, startup, taxi, take off, climb, decent and landing The W to is the assumed takeoff weight for the aircraft at this flight, while the fuel fraction in cruise is calculated from equation 3  Step 1. From mission specification Step 2. Wto guss from similar airplanes Step 3. Determine Wf  Step 4. Calculate Airplane Operating Weight Empty Woe = Wto -Wf -Wpl Step 5. Calculate We Wetent = Woe -Wtfo -Wcrew Wcrew from mission specification Wtfo trapped unusable fuel and oil Wfto = 5% Wto Wtfo = 0.005 × Wto Step 6. Allowable value for We from figure 2.9 or from eq. 2.16  Next the actual Direct Operating Cost DOC, components is calculated. The DOC is calculated by using the method used in [2], starting with the DOC of flight. Within the DOC of flight the cost of the crew, fuel and oil, and insurance all can be directly determined. All values for the crew cost were assumed based on the values from the local airline and [3]. As were the input values for the fuel and oil cost and insurance. [ Table 2].
DOCmaint is the direct operating cost of maintenance in $/n.m.
DOCdepr is the dirct operating cost of depreciation in $/n.m.
DOClnr is the direct operating cost of landing fees, navigation fees, and taxes in $/n.m.
DOCfin is the direct operating cost of finance in $/n.m.

n.m. nautical miles
The DOCfly is given by Ccrew is crew cost given by nc j is the number of crew member of each type (i.e. captain, and co-pilot) V bl is the airplane block speed in n.m/hr.   More details are available in [2].
The the DOC of maintenance was calculated, mostly based on the values from a local airline and values founded in [2]. This was also true for the DOC of the depreciation, as well as the DOC of the landing and navigation fees. Once all of these components were calculated, the total direct operation cost could be calculated by just adding these values together, for each of the flight scenarios. The unite of DOC is dollars per nautical miles After calculating DOC, and with the known distance and the seats for each aircraft at each sector, the cost efficiency chart could be generated and determined (Table 3). Figures 2 and 3 shows the efficiency of each aircraft at a given sector. Different aircraft types are not only compared with their trip cost but also with their seat mile cost, the lower the two parameters for the given aircraft the better, the aircraft is said to be more efficient if both parameters are low.

Conclusion
• In the cost efficiency chart the best-performed aircraft in this sector would be the lowest seat mile cost and the lowest aircraft trip cost.
• B737-500 has the highest seat mile cost but the lowest trip cost for each sector.
• A321 has the lowest seat mile cost but has the highest trip cost.
• Since it is preferential to have the lowest seat mile cost and the lowest trip cost the A319 performed better than the B737-500 and A321.   Table 3: Direct operating cost in $ per n.m.