由營運效益探討航空公司機隊改裝時程及航機生命週期模式

Abstract

近年來在世界景氣的穩定復甦下，加之中國大陸經濟強勢成長，由遠東至世界各地的航線，無論客運或者貨運的需求都急速成長，然而二者之景氣循環，存在時間與量上之落差。本研究以航機生命週期結合航機創造收益及營運成本隨時間變化的觀念，對個別航機建立生命週期模式，分別由預期營收以及營運成本項切入，並同時將客運機及貨運機的不同特性納入考量。以僅有成本支出而無營收檢視客機改裝貨機時程之航機機會成本，及相對反應在航機出廠後營運成本函數與營收函數的變化情形。再由預期營收及營運成本建構隨時間變動之航機營運效益。將灰色模式所預測之貨物運輸及旅客需求量結合馬可夫鏈模式作波動機率預測後，並以動態規劃構建機隊規劃數學模式，以最大化航空公司機隊營運效益為目標，得出最佳機隊更新決策及時程。最後以機隊改裝時程之決策結果結合航機生命週期之動態變化，尋求以此決策模式下，個別航機最大營運效益之航機改裝最佳時點，並進一步評估相較於未改裝情況之效益改善幅度。本研究以一實例進行範例分析，說明模式之應用性，並由改裝效益最大概念尋求最適改裝方案時程，實證結果發現，實例研究航線本身客貨運需求量成長之落差，及相關航線間貨物運輸需求量相對成長幅度之落差，皆為航空公司將客運機改裝為貨運機之主要考量因素，且相關航線之客運需求亦為影響改裝決策之主要因素，並進一步影響是否租賃航機之方式滿足該研究時區之客運需求量。另一方面，採行改裝方案對個別航機營運效益產生之增益，亦使其可作為航空公司機隊簡化時之配套考量。最後本研究再納入航機購置成本之折舊攤提概念，作為航空公司在考量個別航機營運效益與其財務運用彈性情形下之航機改裝決策影響因素。

In recent years, due to the steady revival of world economy and the strong development of China economy, the demand of air traffic from far east to the worldwide has been continuously increased no matter passenger or cargo volumes. However, there exist differences in terms of time gap and growth rate between passenger and cargo demand as regard to their relationships with economic cycles. This research aims to formulate a life-cycle model for an objective aircraft based on the concepts of aircraft life-cycle, time dependent profit gain, and operating costs. The differences in the characteristics of passenger and cargo fleets are also taken into account to formulate the expected revenues and operation costs for aircraft used for two types of services. The costs involved in the process of conversions are age-related and include opportunity costs in terms of loss in operating revenues. The decline in operating cost and the increase in operating revenue after aircraft conversion are also considered. Moreover, the study formulates a dynamic programming model by maximizing airline fleet operating efficiency, and applies Grey forecasting model and Markov Chain to forecast future cargo and passenger demand fluctuation. Then, the study combines the result of fleet model, and individual aircraft life-cycle model to evaluate the profit improvement due to conversion decision. Finally, the study illustrates the application of the models by performing a numerical analysis. The results show the optimal conversion time points for the example fleet, and indicate that improvements in the operating efficiency of aircraft conversion, depend on the extent of reduction in the expenditure and the increased level of air cargo demand on related air routes. The passenger demand on related air routes could be a major factor, which also affect the decision on leasing passenger aircraft to meet the demand. The results also reveal that the conversion decision can be considered jointly with the simplification of aircraft type. Furthermore, the depreciation amortization related to the efficiency of individual aircraft and financial feasibility are further incorporated into individual aircraft conversion decision.