Recently, there has been much interest in measuring the environmental impact of short-to-medium-haul flights. Emissions of CO₂ are usually measured to consider the environmental footprint, and CO₂ calculators are available using different types of approximations. We propose analytical models calculating gate-to-gate CO₂ emissions and travel time based on the flight distance and on the number of available seats. The accuracy of the numerical results were in line with other CO₂ calculators, and when applying an analytical fitting, the error of interpolation was low. The models presented the advantage with respect to other calculators of being sensitive to the number of available seats, a parameter generally not explicitly considered. Its applicability was shown in two practical examples where emissions and travel time per kilometre were calculated for several European routes in a simple and efficient manner. The model enabled the identification of routes where rail would be a viable alternative both from the emissions and total travel time perspectives.

The sustained growth of air traffic over the past decades has increased the aviation’s contribution to anthropogenic radiative forcing through both ${CO}_2$ and non-${CO}_2$ emissions. Although the industry has committed to achieving net-zero emissions by 2050, this goal appears unrealistic without curbing, or at least stopping, the continued rise in traffic. To assess the potential of alternative travel options and quantify their environmental benefits, simple and flexible emission models are needed. In this work, we present a set of analytical models for estimating fuel consumption and associated emissions, including ${CO}_2$, SO_x, water vapour, and other key non-${CO}_2$ emissions such as NO_x and carbon monoxide. We also examine the emissions of non-volatile particulate matter. These models require only flight distance and aircraft seat numbers, enabling broad applicability across traffic scenarios. The models are openly available via a GitHub repository, and their practical use is demonstrated through a case study of a representative day of Spanish air traffic.

This article explores the potential impact of short-haul flight bans in Spain. We build the rail and flight network for the Spanish peninsula, merging openly available ADS-B-based data, for the reconstruction of air schedules and aircraft rotations, and rail operator data, for the modelling of the rail network. We then simulate a ban that would remove flights having a suitable train replacement, \ie representing a trip shorter than a threshold that we vary continuously up to 15-h. We study the impact in terms of 1) air route reduction, 2) aircraft utilisation and fleet downsizing for airlines, 3) airport infrastructure relief and rail network requirements, 4) CO2 emissions, and 5) possible itineraries and travel times for passengers. We find that a threshold of 3 hours (banning all flights with a direct rail alternative faster than three hours) presents some notable advantages in emissions while keeping the aircraft utilisation rate at an adequate level. Interestingly, the passengers would then experience an increase in their itinerary options, with only a moderate increase in their total travelling times.

Los aeropuertos son fuente de prosperidad económica, pero los aeropuertos principales de muchas ciudades están llegando al límite de su capacidad. Frente a las dificultades de expandirlos, el desarrollo de sistemas multiaeropuerto puede ser un mecanismo para adaptarse a la presión de la demanda. Sin embargo, los sistemas multiaeropuerto son difíciles de desarrollar, ya que no existe una tipología clara y dependen de particularidades locales. Por otro lado, y seguramente sea lo más relevante, las aerolíneas tienen pocos incentivos para operar en aeropuertos secundarios. En un mercado liberalizado, las aerolíneas siempre tenderán a concentrar su actividad en el aeropuerto principal. En este artículo presentamos estos principios básicos de funcionamiento que hacen de los sistemas multiaeropuerto un equilibrio difícil, aunque interesante de tratar de conseguir.