Bad weather can play havoc with the best-laid plans. This is especially true in air traffic management, where poor meteorological conditions are the cause of an estimated 20 % of all traffic delays in Europe. Performing better during adverse weather relies on timely and accurate forecasts, which is easier said than done given how quickly the conditions can evolve. Closing the gap on the uncertainty brought about by weather has been a focus of a number of SESAR research and innovation projects over the last two years.
Integrating meteorological uncertainty into flow management
Adverse weather has a significant impact on air traffic. It is estimated that poor meteorological conditions en-route are responsible for about 4 million minutes of delay every year in Europe. Delays come about because bad weather makes air traffic difficult to predict and complex to manage, resulting in reduced airspace capacity. “It is quite challenging, mainly because forecasting adverse weather is very difficult, even for short lead times. Furthermore, the accuracy of the weather prediction rapidly degrades with the forecasting horizon. Quantifying the weather forecast uncertainty is the main difficulty, and its analysis requires a probabilistic approach,” explains Alfonso Valenzuela, one of the principal researchers in the SESAR project, FMP-MET.
The project looked at how to best integrate MET forecast uncertainty information into the decision-making process for flow management positions (FMP), an operational position that monitors the level of traffic in airspace sectors and coordinates flow measures when an excess of demand over capacity is detected. The research team developed a probabilistic methodology to forecast traffic congestion and traffic complexity to be used in conjunction with the tools currently employed by FMPs. An innovative feature of the FMP-Met tool is its ability to provide the FMP with an intuitive and interpretable probabilistic assessment of the impact of convective weather on the traffic, up to 8 hours in advance, to allow better-informed decision making. The next steps in this research should lead to the development of a prototype tool, in close collaboration with FMPs, implementing the FMP-Met concept.
Of course, predicting the weather is an important part of network forecasting and performance. The ISOBAR project prototyped a storm forecaster tailored to air traffic management and a user-driven mitigation plan that takes into account flow constraints and network effects. The set of weather management boosters includes a neural network that integrates convective prediction into a structured airspace map, together with a set of AI modules, such as AI-based hotspot detection and adaptive mitigation measures, to support decision-making by the human operator. The project also developed an operational and technical roadmap for the integration of ancillaries into the Network Manager platform by defining interfaces, and functional and performance requirements.
“The project results are expected to improve convective weather forecasts, anticipate the detection of demand - capacity imbalances in the network and provide optimal mitigation solutions. This means better situational awareness of the operating environment, which at end of the day, means better decision-making and performance all around,” says Marta Sánchez Cidoncha, ISOBAR project coordinator.
FMP-MET: https://fmp-met.com
ISOBAR: https://isobar-project.eu/
Sounding the alarm on natural hazards
Bad weather is not just a nuisance for air traffic, it can also be hazardous. “Serious damage can be caused to aircraft if smoke, dust or even sea salt are ingested by engines, due to both the erosion and corrosion they cause, and possible obstructions, or because they affect in-flight combustion,” explains Manuel Soler, ALARM project coordinator. “Volcanic ash and gases, such as sulphur dioxide, are also important hazards, causing abrasions to windscreens, corrosion to engines, and different damage to aircraft systems and instruments, while electromagnetic radiation from the sun can interfere with aircraft communication systems,” he adds.
The ALARM project developed a system that monitors and gives early warnings about natural events that pose a risk to aviation, but also considers the environmental impact of these events as a further hazard. The early warning system prototype can be integrated into ATM systems as an application programming interface (API) providing nowcasting (up to 2 hours) and short-term forecasting (up to 6 hours) of SO2 plumes at a regional scale and of severe thunderstorms at a local scale (airport). It also provides forecasting and medium-term forecasting (up to 48 hours) of climatic hotspots at a European scale. The requirements of all these products have been included in the system-wide information management (SWIM) yellow profile to facilitate data exchange.
Managing bad weather around airports
Today, especially at larger airports, controllers use air traffic control support systems to help them organise and guide arriving and departing traffic. However, these systems do not yet have the capability to use weather measurements or forecasts to calculate flight routes around, for example, thunderstorms. “If extreme weather areas occur, the pilots decide on which side and at what distance they will fly around them. Controllers then have to calculate manually separation infringements with other aircraft,” explains Antonio Parodi, coordinator of the SINOPTICA project.
The project developed a module for an extended arrival manager (Extended AMAN) system that uses current weather information and forecasts to plan the approaching traffic around the developing weather at an early stage. It is integrated directly into the working position of approach controllers and works seamlessly with existing systems. In case a severe weather area blocks the route, the AMAN calculates new approach routes around the dangerous areas with new arrival times and new positions in the landing sequence. The controllers responsible get advisories where and for how long the aircraft have to leave the standard approach routes and at which target times they will be at the main waypoints of the route. Additionally, the systems allow controllers to visualise the predicted and animated severe weather areas.
Climate impact and weather
Weather and climate change are inextricably linked, which is what prompted the CREATE project to assess the impact of ATM operations on the climate, while also improving resilience to weather phenomena in a changing climate. “The changing global climate increases the future severity and frequency of disruptive weather phenomena. This deteriorates the reliability of ATM network planning and increases potentially the delays within air traffic operations,” says Angelo Ricco, CREATE project coordinator.
The project developed a climate and weather-aware concept of operations (ConOps) encompassing a multi-aircraft four-dimensional (in space and time) trajectory optimisation framework. It also built an environmental scoring module (ESM) to evaluate the “greenness” of aircraft trajectories. This considers CO, non-CO emissions and contrail probability formation during the en-route phase of flight, in addition to NO and particulate matter emissions (related to the impact on air quality) during the approach and departure phase. The algorithmic approach is fast enough to be easily implemented at different stages of the trajectory lifecycle; for example helping to resolve hotspots in the network due to weather hazards, or air quality sensitive regions, taking into account evolving traffic.
Non-CO emissions are also assessed in the FlyATM4E project; the climate impact of such emissions is strongly dependent on weather and varies considerably according to atmospheric conditions, such as air temperature and altitude. “Non-CO effects, such as contrail cirrus clouds (ice crystals that form behind an aircraft) and NOx-induced changes of ozone and methane, upset the radiative balance of the atmosphere. They can cause both warming and cooling effects and, unlike CO, do not follow a linear pattern but contribute to both positive and negative effective radiative forcing (ERF),” explains Sigrun Matthes, coordinator of the FlyATM4E project. The project modelled these climate impact metrics in multiple environments with a focus on intra-European flights, and explored the feasibility of a concept for aircraft avoiding the more sensitive areas, otherwise known as “big hits”. Their modelling found that in most cases it should be possible to apply effective re-routing strategies to support eco-efficient routes and climate-optimised aircraft trajectories.