Based on the use of a qualitative longitudinal research design, this study examines Cargolux Airlines International, a major global air cargo airline, sustainable energy management. The study covers the period 2012 to 2020. Cargolux Airlines International energy sources are aircraft (Jet A1) aircraft fuel, diesel, cooling energy, electricity, heating energy, industrial fuel, natural gas, and unleaded gasoline 95. The case study revealed that Cargolux’s Jet A1 fuel consumption has principally exhibited an upward trend reflecting the growth in the airline’s services, route network expansion, and the growth in the aircraft fleet during the study period. Cargolux Airlines International annual cooling energy consumption (kWh) oscillated over the study period reflecting differing cooling requirements. Cargolux Airlines International annual diesel consumption fluctuated quite markedly during the study period reflecting differing vehicle fuel consumption requirements and usage. The case study found that there was a general downward trend in Cargolux Airlines International annual electricity consumption during the period 2012 to 2015, whilst there was a general upward trend in the airline’s electricity consumption from 2016 to 2020. The airline’s annual heating consumption also oscillated over the study period reflecting differing heating requirements. Cargolux Airlines International annual industrial fuel consumption primarily displayed a general downward trend. The airline’s annual natural gas consumption has fluctuated throughout the study period reflecting differing consumption patterns at the airline. Cargolux annual 95 gasoline consumption displayed a general downward trend from 2012 to 2015, and a general upward trend from 2015 to 2020. Throughout the study period, Cargolux Airlines International implemented a range of energy savings measures that enabled the airline to optimize its energy consumption.