Structural improvements in aircraft design, seeking to improve energy efficiency, can significantly reduce greenhouse gas emissions (GHG) by reducing reduced fuel consumption. This research reviews improvements with the introduction of a structural component known as "winglet;" these are positioned at the top of the aircraft wing, and increased Airbus Group A320 sales. Data used are taken from air traffic in Spain for the 2010-2014 period with projections being made for 2020. The results show that winglets reduce CO2 equivalent emissions associated with Spain's air transport for the 2015-2020 period between 66.29 and 59.56 Gg. depending on the scenario considered in 2020.