Evolved version of Advanced Weather Awareness System in the COAST Project: latest developments and validation

In the framework of the COAST (Cost Optimized Avionics SysTem) project, the Integrated Mission Management System (IMMS) has been developed, a technology aimed to automatically optimize the trajectory of Small Air Transport (SAT) vehicles considering, among possible obstacles, weather conditions, air-traffic and terrain. It is based on the interaction of the evolved versions of three systems, realized within COAST, including the Advanced Weather Awareness System (AWAS), devoted to provide on-board data regarding weather hazards monitored and forecast. The Evolved-AWAS technology has been developed by introducing several enhancements to its baseline version, in order to generate additional information required by IMMS for trajectory optimization. The current work describes the latest developments of Evolved-AWAS and the tests carried out to validate the prototype. All the new functionalities were tested verifying the correct generation of output data needed by IMMS and their visualization into the HMI (Human Machine Interface). The positive results of the performed tests ensured the proper functioning of the software, allowing its integration in the IMMS technology. Finally, the paper reports the outcomes of the last COAST flight demonstration campaign held in June 2023, which revealed the correct behaviour of the Evolved-AWAS, as well as of the overall IMMS.


Introduction
Within the COAST (Cost Optimized Avionics SysTem) project [1], funded by Clean Aviation Joint Undertaking in the European Union's Horizon 2020 Research and Innovation Programme, several technologies have been developed since 2016 for cockpit and avionics of Small Air Transport (SAT) vehicles.One of them is the Advanced Weather Awareness System (AWAS, [2]- [3]- [4]), aimed to increase the pilot weather awareness, providing on-board of the aircraft updated data regarding observed and forecast weather hazards.This system was successfully tested during the first COAST flight demonstration campaign held in 2021, highlighting its correct functioning in processing and visualizing the data [4], leading AWAS to reach the TRL6 (Technology Readiness Level) maturity level.Meanwhile, in 2020 the design of the Integrated Mission Management System (IMMS, [5]- [6]) started, devoted to automatically optimize the trajectory considering weather conditions, air-traffic, terrain and other kind of obstacles.To this aim, it was necessary to allow the interaction of three different COAST systems, individually developed since the beginning of the project: FRS (Flight Reconfiguration System [7], managing the flight path in case of pilot's incapacitation), TSS (Tactical Separation System [8]- [9], managing tactical traffic separation and enhanced situational awareness) and AWAS.This required to introduce new functionalities in each technology, leading to the development of their related evolved versions, Evolved-FRS (core of IMMS) [6], Evolved-TSS [10] and Evolved-AWAS [11], to be integrated into IMMS.Concerning Evolved-AWAS, several enhancements were made to its baseline version, with the purpose of generating and managing new data required by the Evolved-FRS to optimize the trajectory in case of presence of adverse weather conditions along the flight route.The main features of Evolved-AWAS are reported in detail in [11]; the present paper describes the last modifications made to the technology and all the activities performed to verify its correct functioning in view of the last COAST flight demonstration campaign, during which IMMS system was validated.Specifically, a brief description of Evolved-AWAS is reported in Section 2; Section 3 illustrates the tests performed in laboratory to validate the technology whereas Section 4 provides the results of the flights made in June 2023.Finally, the main conclusions are reported in Section 5.

The Evolved-AWAS system
The AWAS system, described in detail in [3]- [4], consists of three main components: AWAS on-ground, AWAS on-board and AWAS HMI (Human Machine Interface).The on-ground segment, running at CIRA, generates on-ground and provides on-board compressed text files reporting coordinates and severity level of polygons enclosing the areas affected by weather hazards, extracting data over an area centred on aircraft position from MATISSE (Meteorological AviaTIon Supporting SystEm [12]) geodatabase of the CIRA Weather Data Ground Repository.Concerning AWAS on-board, running in the Compact Computing Platform (CCP, [13]) of the aircraft, it is devoted to provide on-ground information about date and aircraft position extracted from GNSS (Global Navigation Satellite System) and to elaborate data received from the ground, generating JSON (JavaScript Object Notation) files used by the AWAS HMI to display the weather information on a PED (Portable Electronic Device) on board of the aircraft.The on-ground and on-board segments are connected each other through a low-cost Satellite Communication System (TLC-SAT) and the exchange of data occurs by means of an FTP onground repository.The Evolved-AWAS maintains all these functionalities while introducing new ones in order to allow the generation of data required by Evolved-FRS, core of IMMS, to perform the route re-planning.Specifically, in addition to the information already provided by the baseline AWAS, altitude limits of hazards and the coordinates of centre and radius of the circles enclosing the areas to be avoided have to be defined by the prototype.The new functionalities introduced in the technology are described in detail in [11] and briefly summarized in the following.The design of Evolved-AWAS started with the definition of an evolved architecture (shown in Figure 1) in which a new interface with Evolved-FRS is added and the old ones are updated, in order to permit the exchange of new data within Evolved-AWAS; indeed, a new IMMS file is produced as output by the on-ground segment and provided on-board through the FTP repository, allowing the generation onboard of new data both for the HMI and the Evolved-FRS.Concerning the Evolved-AWAS on-ground application, new weather data were integrated into the system and new methods were developed to retrieve minimum and maximum altitude for each weather hazard.Furthermore, new functions were implemented to define the circles enclosing polygons identified to represent hazard areas.Then, all the data required by Evolved-FRS, namely kind of hazard, severity level, coordinates of polygons vertices, centre and radius of circles and altitude limits, are provided in a new compressed text file by adopting a suitable format agreed with the project partners.Finally, the generation of a new log file was implemented, in order to have a more detailed reporting of the status of the process.All these changes were integrated into a unique MATLAB code that performs both baseline and evolved functionalities.Additionally, new settings were adopted in the logging of the FTP on-ground server to preserve as much information as possible during the execution of the flights.For what concerns the on-board segment, it was initially based on three different applications, exchanging data with each other, each one dedicated to a specific function (i.e.FTP data exchange, generation of JSON files for observations and forecasts) [4].Afterwards, in order to improve the data synchronization on board, the architecture of Evolved-AWAS was redesigned, developing in C++ a unique application that performs all the necessary functionalities.Moreover, new methods have been implemented and the baseline ones have been upgraded with the aim to retrieve from the FTP, decompress and decode the new file sent by the on-ground segment.Data are then processed and the corresponding information are provided to Evolved-FRS, for IMMS purposes; a new JSON file is also generated to allow the visualization on-board of data through the HMI.Finally, the writing of a log file has been introduced in order to report information needed to analyse the process execution.In terms of HMI, consisting of a Javascript code implemented in Software Development Kit (SDK) environment, a new layer was added in the Evolved-AWAS to display circles enclosing polygons by using two different colours, on the base of the hazard's severity: yellow in case of moderate level and red for severe level.

The Evolved-AWAS validation
The baseline AWAS prototype was successfully validated in laboratory in the previous project phases through the execution of several tests, described in detail in [4], aimed to evaluate the capability of each system component to automatically generate the correct output data.The tests previously carried out remain still valid also for the Evolved-AWAS, since it includes all the features of its baseline version; however, the proper behaviour of the prototype needs to be assessed with respect to the new functionalities introduced, verifying:  the correct generation of the new IMMS text file produced by Evolved-AWAS on-ground,  the correct generation of the new IMMS JSON file produced by Evolved-AWAS on-board,  the correct representation of IMMS additional information in the Evolved-AWAS HMI.Different tests were carried out by using the CIRA computing systems as fast-time SW simulation environment, also performing long-time tests (3 scenarios lasting 1800 seconds and 1 scenario lasting 2000 seconds).At first, the capabilities of the prototype to correctly associate to each hazard minimum and maximum altitude values and numerical parameters representing severity level were assessed.Moreover, the inclusion of each polygon in the associated circle identified by the prototype was checked.To this aim, specific functions were developed in MATLAB and control maps were used to verify the correctness of the data for several test cases, considering both observed and forecast weather conditions.For what concerns the output of the Evolved-AWAS on-ground, several checks were performed to evaluate if the information reported in the new IMMS text file is correct, including a comparison between this file and those produced by the baseline version of AWAS.An example is provided in Figure 2, in which the data obtained by the prototype for a specific date and time are displayed: Figure 2 (a) and Figure 2 (b) show the output of the baseline AWAS (text files reporting vertices of polygons and severity level for each hazard and an additional file with supplementary information about the weather data) for observations and forecasts respectively, whereas Figure 2 (c) shows the new text file generated for IMMS (reporting all the data required by Evolved-FRS).This picture highlights the correspondence among the information regarding kind of hazard, severity level and coordinates of polygon vertices, for both observed (outlined in orange) and forecast (in blue) hazards.The format of the IMMS text file (shown in Figure 2(c)) was also checked, ensuring its compliance with the one agreed with the project partners.Concerning the output of Evolved-AWAS on-board, the correctness of produced JSON files was verified by comparing them with the corresponding IMMS text files generated by the on-ground segment.
In terms of visualization, the capability of the prototype to reproduce in SDK environment the Evolved-AWAS information was assessed.Specifically, the functioning of the third layer introduced in the HMI was checked, verifying the appearance of the circles associated to each polygon when the corresponding layer is selected into the dashboard.Additionally, the maps visualized in the HMI were compared with the ones generated on-ground by the MATLAB prototype as shown, for example, in Figure 3, in which the correct match of displayed data is pointed out.Finally, the timing for files generation and storage was monitored to verify that the execution time of Evolved-AWAS is acceptable and lower than the established refresh rate.Additionally, the dimension of all produced files was analysed to assure that the COAST requirements of data throughput are satisfied (i.e.not exceeding 150KB).
Once ensured that the new functionalities were correctly developed and integrated in the prototype, its behaviour under off-nominal conditions was assessed.Specific tests were performed to verify that Evolved-AWAS on-board does not crash if there are connection problems or the FTP repository is offline, also evaluating the cases of unavailability of on-ground application or reception of corrupted files from ground.Regarding Evolved-AWAS on-ground, instead, its behavior was verified when wrong input files are generated by the on-board application.
During this off-nominal lab testing phase, several checks were implemented to enhance the performance of the prototype, so that all the tests revealed the correct functioning of Evolved-AWAS, never crashing in the above described situations and resulting compliant with the IMMS requirements applicable to Evolved-AWAS technology.
The positive results of the validation allowed to deliver the prototype for the integration into IMMS system, permitting its final testing before the execution of the flight demonstration.

Results of flight demonstration campaign
In view of the flights, a preliminary activity was performed concerning the selection of dates characterized by weather conditions of interest, identifying days and times when weather hazards occurred close to Prague airport and, more generally, in the area between Kunovice and Prague planned to be used for the flight demonstration.The aim was to use these meteorological data during the demonstration to allow Evolved-FRS, integrated into IMMS, to perform the flight reconfiguration in response to the presence of adverse weather conditions along the route.The final COAST flight campaign was carried out in June 2023 around the Kunovice International Airport (Czech Republic) using the EVEKTOR EV-55 aircraft.During this campaign, IMMS (and therefore also Evolved-AWAS integrated into it) was validated.All the data generated during the flights were analysed to assess the proper working of the Evolved-AWAS system.At first, the comparison between JSON files created on-board and TXT files available on-ground was performed.Moreover, the HMI images were compared to the PNG files produced by the on-ground segment to assess the correct representation of data.As an example, Figure 4   Additionally, the log files of FTP on-ground server and Evolved-AWAS on-board application were examined, revealing several information concerning the process execution.The file generated on-board showed the correct working of the application in the CCP of the aircraft; moreover, analysing the log available on-ground, the timing of retrieval of text files from the FTP was assessed, highlighting the right correspondence with the time of their storage on-board and generation of related JSON files.All the analyses highlighted that Evolved-AWAS system integrated into IMMS behaved as expected: the weather hazard data were correctly received, elaborated and represented on-board in real-time, allowing the generation of information needed by Evolved-FRS to manage the flight path re-planning.

Conclusions
The present work describes the evolution of the Advanced Weather Awareness System (AWAS), a technology designed in the framework of the COAST project with the aim to increase the weather awareness of the pilots of Small Air Transport (SAT) vehicles.AWAS was successfully developed during the first phases of the project; afterwards, it emerged the need to develop an evolved version of the system (Evolved-AWAS) in order to permit its integration into the Integrated Mission Management System (IMMS), a new COAST technology devoted to allow autonomous operations on board, optimizing the trajectory considering obstacles such as terrain, air traffic and weather hazards.At first, new interface specifications were defined to ensure the interaction between Evolved-AWAS and the other on-board systems integrated into the Compact Computing Platform of the vehicle.Then, with respect to its baseline version, several enhancements were introduced into the on-ground and onboard segments of Evolved-AWAS, in order to integrate new input data and generate new output needed by IMMS for the re-planning of the route in case of presence of adverse weather conditions.The Human Machine Interface (HMI) was enhanced too, by introducing the possibility to visualize on-board of the aircraft all the data generated by the technology, including the new ones required by IMMS.The development of Evolved-AWAS was completed and the prototype was validated at first in laboratory, through the execution of several tests aimed to evaluate its functioning with respect to the new functionalities introduced, also considering off-nominal conditions.The positive result of the tests allowed the integration of Evolved-AWAS into IMMS system.Then, the final prototype was validated during the last COAST flight demonstration campaign carried out in June 2023 around the Kunovice International Airport.The post-flight data analysis pointed out the correct working of Evolved-AWAS once integrated into IMMS: all the available data generated by the on-ground and on-board segments during the flights were examined, revealing that the weather data were correctly processed and visualized on-board, allowing IMMS to perform the route re-planning when necessary.Hence, the last flight campaign of the project was successfully conducted, leading the Evolved-AWAS prototype to the achievement of the TRL6 maturity level.

Figure 2 .
Figure 2. Example of comparison between text files generated by the baseline AWAS, for OBS (a) and FCST (b), and the new IMMS text file generated by Evolved-AWAS (c).

Figure 3 .
Figure 3. Example of comparison between images generated by on-ground segment, for OBS (a) and FCST (b), and image obtained through HMI (c).
reports a selection of data analysed for a specific date and time used during the flights: Figure4(a) shows the new text file generated on-ground for IMMS; Figure4(b) displays an image produced on-ground, which represents polygons and circles enclosing areas affected by weather hazards, superimposing in a unique image both observations and forecasts; Figure4 (c)shows the image of HMI extracted from the video recordings of the PED display.This picture points out the correspondence between the data generated on-ground and on-board, revealing a correct processing of the weather data by the Evolved-AWAS prototype.

Figure 4 .
Figure 4. Example of data generated during the flight demonstration: IMMS text file (a) and image representing OBS and FCST hazards (b) obtained on-ground; image produced by HMI (c).