Evaluation of Intermediate Refueling Stops in Long-Haul Flight Operations

The aviation sector has suffered a big blow from the series of recent economic depressions. Airlines are struggling to stay in business and are looking for multiple ways to cut on expenses. This has led to the initiation of studies to find strategies which will reduce an airline’s overall fuel consumption. One of these methods is to initiate intermediate refueling stop operations on long-haul flights. This means that instead of flying with a fully fueled aircraft from e.g., Amsterdam to Tokyo, the route is split into two or more segments which are flown with the appropriate amount of fuel and possibly even different aircraft types more suitable for shorter range flight. By developing a novel computer model, this research aims at finding the answers to the following questions: \u95 What are the fuel consumption- and emission savings that can be attained by implementing this model on specific routes and with specific aircraft types? \u95 What are the route requirements to optimally benefit from operating flights with intermediate refueling stops? \u95 Which costs are directly linked to introducing refueling stops, what are the consequences and what can be done to reduce these costs? \u95 How does this concept influence the airport groundside operations and what is the impact on the airport infrastructure? The model consists of two independent programs which work in cohesion to find the optimal stopover airport for a specific route operated by a specific aircraft. The first program is the aircraft model, which is capable of calculating the fuel consumption on a specific mission. The calculations are based on the fundamentals of flight and the equations of motion. In total three aircraft types are incorporated and together cover short-, medium- and long range operations. The second program is the route model which is able to identify the costs for a specific segment and determines the optimal route by use of a modified version of the Dijkstra Algorithm and an airport database of ILS Cat. II/III equipped airports. This model computes a buffer zone in which to look for intermediate stop airports and selects the most advantageous option, based on local waiting times, landing- and navigation fees and fuel prices. The results show that on routes suitable for intermediate stop operations, the fuel reduction ranges from 5% - 10%. For the total cost reduction, these values are around 2% - 4% per flight. These figures strongly depend on the mission conditions and stopover position. Besides the fuel price and stopover time, the wind velocity and direction also have a vital role in the feasibility of the concept.Air Transport and Aerospace OperationsControl and OperationsAerospace Engineerin