**1. Introduction**

In some regions of the world, adverse weather conditions such as thunderstorms and hailstorms (convective cells) are one of the biggest challenges in commercial aviation as they can have major impacts on air traffic control (ATC) and airlines in terms of safety and capacity [1]. Climate change is intensifying the water cycle [2], thus bringing more intense rainfall and associated flooding, as well as more intense drought in many regions. Current studies suggest that aviation contributes to between 2% and 3% of global warming in the long term through CO2 and in the short term through methane and contrails [3]. It is expected that climate change, through its impact on atmospheric processes, especially on short-lived and highly localized phenomena (thunderstorms, hailstorms, etc.), will also affect air traffic management activities. This phenomenon, also commonly known

**Citation:** Temme, M.-M.; Gluchshenko, O.; Nöhren, L.; Kleinert, M.; Ohneiser, O.; Muth, K.; Ehr, H.; Groß, N.; Temme, A.; Lagasio, M.; et al. Innovative Integration of Severe Weather Forecasts into an Extended Arrival Manager. *Aerospace* **2023**, *10*, 210. https://doi.org/10.3390/ aerospace10030210

Academic Editor: Spiros Pantelakis

Received: 24 January 2023 Revised: 21 February 2023 Accepted: 21 February 2023 Published: 24 February 2023

**Copyright:** © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).

as thundercloud, is a main safety risk and can require circumnavigation, thus disrupting air traffic flow, increasing delays, and lowering cost-efficiency. At many major airports, capacity potential is already largely exhausted as global air traffic has continued to grow in recent years [4]. Despite economic fluctuations and the influence of the COVID-19 pandemic, a recovery and further steady increase in flight movements is also predicted for the future [5]. With narrow airspaces and the high density of movements, the probability of flight delays increases in adverse weather conditions.

For more than 9% of the first half of 2018, Munich airport was affected by thunderstorms around or close to the Alps [6]. In 2019, EUROCONTROL reported that 21% of the delayed flights in Europe were caused by adverse meteorological conditions [4]. Around 10% of all European departure flight delays result from adverse weather, varying between 2% at Charles de Gaulle in Paris and 20% in Istanbul [7]. In Austria, 95% of regulated airport traffic delays were caused by weather in 2018 [8]. In addition to reduced visibility [9], snow, short-term de-icing operations, and other strong weather events sometimes make areas of airspace impassable. Unfortunate weather situations are also responsible for the complete closure of airports [10]. The cost of a hub airport closure, for example, can exceed three million EUR per hour for all stakeholders combined [11]. The enormous economic significance that adverse and extreme weather events can have on aviation is also becoming apparent.

An early and coordinated avoidance of adverse weather conditions can make en-route flights and approaches more efficient; however, there are currently no appropriate solutions that are operationally available for a guidance system that takes dynamic and convective weather into account. Consequently, ATC requires innovative solutions for avoiding emerging severe weather during flight. Adverse weather is often limited to regional areas; however, when blocking main flight routes, this can have a significant impact on overall air traffic. Thus, it is of utmost importance to support air traffic stakeholders both on board and on the ground. If appropriate nowcast and forecast weather data are available, the process of circumnavigation can be improved by implementing computer-based air traffic controller and pilot support systems. These systems support ATCOs with route information, altitude and speed advisories, and enhanced traffic displays with weather cells and affected aircraft visualizations. To avoid areas with flashes and hail, diversions should be designed in a way that pilots and ATCOs are able to choose their routes according to their training and experience. This paper describes the technical implementation of an air traffic controller support system for adverse weather situations in the vicinity of airports. In addition, an initial validation of the prototypical system and its results is described, which will be incorporated into the further development of the used arrival manager.
