Abstract
Abstract
A case study has been performed to analyse the influence of geometric altimetry on aircraft flight efficiency in climb and descent if using global navigation satellite systems (GNSS) instead of barometric altimetry in the future. Geometric altimetry would allow more precise altitude measurements, but because the flight performance is depending on the atmospheric conditions and not directly on the geometric altitude, there are several effects on the flight performance. These effects have to be considered in order to determine whether geometric altimetry would result in a fuel benefit or in a fuel penalty. For the purpose of this study, an Airbus A320 simulation model identified from flight test data has been modified in order to allow a comparison of flights with barometric and geometric altimetry for several climb and descent procedures. The results show that there is a very small but slightly positive benefit with the use of geometric altimetry, but there can also be additional indirect benefits due to an optimisation of the procedures enabled by geometric altimetry. However, the benefits are strongly depending on the details of the scenario and not all aspects of the procedure optimisation always result in positive fuel savings. Generally, the direct benefit of the usage of geometric altimetry can be neglected in many scenarios, but the indirect benefits can justify further research about this topic.