In the past decade, fuel consumption and CO2 emission have increased in the airline industry. Large CO2 footprint has a damaging effect on the environment. Global concerns over this issue have made the airline industry to be greener. Most efforts of the green airline industry are improving the fuel consumption to reduce the CO2 emission and its environmental damage. Here, we use cruise speed control to control the fuel consumption and CO2 emission. Each aircraft has a different speed level needing a different fuel consumption. Service quality is studied besides the energy consumption. We investigate two objectives including total energy consumption (TEC) and passenger service level (PSL). TEC and PSL are conflicting in nature. We develop a mixed-integer nonlinear programming model to integrate schedule design, aircraft assignment and maintenance routing problems. We make use of the augmented ε-constraint method to solve the problem. To evaluate the model, a real data based on the Emirates airline flights is used. The results are compared using four different scenarios.Gholami, Jalalian and Ramezanian environment [39]. Also, there is a limit on CO2 emission in some countries [10]. Therefore, the airline industry tries to be eco-friendly and greener to reduce the damaging environmental effect. Green consideration has an economic benefit besides the positive environmental effects. Green efforts reduce the fuel consumption and CO2 emission in the airline industry. In this way, the fuel cost is reduced. Therefore, managers can price flight ticket at a lower rate. High prices have negative effects on customer loyalty [25], but low prices can attract more passengers and increases the market share. Green efforts can increase revenues by reducing costs and ticket prices. Also, positive publicity of green airlines encourages passengers to pay more for green flights as they pay more for better services [19]. Service quality is another important element to attract passengers. Improving the service level increases passengers' satisfaction and loyalty.Many researchers in operational research took advantage of optimization problems to reduce costs [9]. Results of operational research in the airline problems including schedule design, aircraft assignment and maintenance routing have proven to be effective for the industry [4]. We propose a new bi-objective mixed-integer nonlinear programming (MINLP) model to integrate schedule design, aircraft assignment and maintenance routing problems. We focus on total energy consumption and passenger service level as two conflicting objectives. We consider cruise speed control to overcome the conflict. Not having an effective model may lead to catastrophic damages. For example, an accident occurred for the Brazilian football players while traveling from Brazil to Colombia killing 72 passengers. The accident was due to inappropriate aircraft assignment to the flight. Aircraft fuel tank capacity was not enough for the flight. Therefore, the fuel finished before aircraft reached the destination...