Note: Size related to seat capacity, two-class configuration.
Source: adapted from IEA/OECD (2009) Transport, Energy and CO2: Moving toward sustainability. Paris: International Energy Agency.
Fuel efficiency is an important component of aircraft operations, so the evolution of jet planes goes on par with the evolution of their fuel efficiency (here measured in megajoules per passenger-km). Several factors contributed to the improvements in the energy efficiency of aircraft in recent decades:
- Improvements in engine fuel per unit of thrust: About 70%.
- Aerodynamic improvements: About 25%.
- Other factors such as economies of scale of larger aircraft: About 5%.
An important landmark was achieved in the early 1970s with the introduction of second-generation jet planes (B747 and DC10) that included engine efficiency improvements as well as the economies of scale benefits of high capacities, in the range of 300 to 400 passengers. Structural efficiency improvements, such as weight reduction, made a limited contribution to improved energy efficiency. Rising energy prices have several impacts on airline companies. One involves switching to more fuel-efficient aircraft and retiring those that are less.