Commercial space transportation is becoming more affordable and accessible. Consequently, we expect to see significant expansion of commercial space launch activities in the coming decade. As space vehicles travel through airspace during the launch and re-entry stages, they potentially disrupt the regular operations of traditional users. This paper estimates the potential economic and operational impacts of commercial space horizontal launch activities on airlines under various launch scenarios using predictive fast-time simulation modeling, focusing on Cecil Air and Space Port in Jacksonville (Florida) and the rules governing the national airspace system (NAS) in the United States. Our results indicate that the existing 4-hour airspace closure rule impacts a significant number of flights, resulting in flight time delays, additional flight distance and fuel burn, as well as other direct operating costs. Safely reducing the duration of airspace closures could serve as a simple solution to mitigate the impacts on airlines and other traditional NAS users. More importantly, treating our studied launch vehicle as an aircraft and opening its departure/arrival corridor to air traffic during a horizontal launch and return would potentially reduce the impacts on airlines significantly, depending on the location of the spaceport, planned flight paths and the trajectory of the launch.

SummaryReal‐time (RT) systems include hardware and software components interacting in a tight fashion. Although formal methods for RT systems development have advanced, they are sometimes difficult to apply in practical applications, and scalability is compromised as the complexity of the system scales up. Instead, using modeling and simulation (M&S) methods and tools has showed to be useful for verification of practical aspects of RT systems (and having the advantage to be able to including models of the physical environment they interact with). Although several efforts exist in M&S of RT systems, none of them has considered problems of transient overloading in the RT systems specifications. Here, we introduce a new theoretical framework called I‐DEVS (imprecise discrete event systems specification) with the goal of guaranteeing responses to inputs within specified time constraints under such transient overloading conditions. The solution presented here has the advantages of a formal specification and the practicality of an M&S‐based approach. We also discuss how to define hierarchical models running in RT, and we present a set of tools that can be applied to develop RT‐embedded applications, and RT simulations.

The Federal Aviation Administration (FAA) Academy is challenged with limited availability of Air Traffic Control (ATC) training technologies for their trainees. Due to the number of trainees and cost of operation of ATC labs, trainees can only practice for limited amounts of time, hindering their learning experience. Embry-Riddle Aeronautical University is tasked with building a lightweight and web-based en route ATC simulator that mimics the FAA en route automation environment, allowing trainees to practice ATC scenarios at their own pace. The proposed simulation technology, namely ATC Scenario Training Technology (ASTT) mimics En Route Automation and Modernization (ERAM) functionalities and provides a web-based practice platform to en route trainees, as well as hints on their performance, without requiring any external human or system actors when running a scenario. This research tackled the issue of how to algorithmically fulfil the role of the pilot, the adjacent sector controllers, and the ATC instructor in a browser-based ATC training environment. Several criteria were identified as requirements for such a system to be implemented on the ASTT server to play the role of the above-mentioned actors. In this paper, we present the web-based ATC training environment by detailing the tool features and its unique feedback capabilities serving as an automated supervisory training platform. Front-end as well as back-end mechanism of ASTT technology will be discussed, highlighting tool's design and operation details.

The Federal Aviation Administration (FAA) Academy is challenged with limited availability of Air Traffic Control (ATC) training technologies for their trainees. Training is conducted over simulation scenario runs in dedicated ATC lab spaces under the supervision of ATC instructors. Current ATC training tools lack flexibility and cost effectiveness to provide 24/7 service to the trainees as well as providing dynamic fast prototyping environment for scenario development. Due to the number of trainees and cost of operation of ATC labs, trainees can only practice for limited amount of time, hindering their learning experience. Through a recent funded research project, Embry-Riddle Aeronautical University is tasked with building a web-based ATC En route simulator that mimics the FAA En route automation environment, allowing trainees to practice ATC scenarios at their own pace. The proposed simulation technology, namely ATC Scenario Training Technology (ASTT) mimics En route Automation and Modernization (ERAM) functionalities and provides a web-based practice platform to en route trainees. One technique in capturing software requirements is to study various system usage and functionalities scenarios that highlight top-level and low-level details. To apply this approach to ASTT project, a set of en route scenarios were developed and discussed during the requirements elicitation phase. For each given scenario, key elements were highlighted and relationships amongst them were established. Requirement modeling diagrams and documentations were then constructed, fully capturing ASTT details. In this paper, we demonstrate a rather non-traditional requirements engineering approach in extracting information for building an ATC simulator. Similar to the concept of user stories in software development projects, simulation scenarios can be used to extract essential details for designing and building simulators. ASTT requirements modeling and system architecture are discussed in this paper by presenting a sample ATC en route scenario and discussing our approach in extracting requirements details from it.

Through a recent project for the FAA Academy, an ATC Scenario Training Technology (ASTT) is being developed at Embry-Riddle Aeronautical University to provide the Academy students with an online tool to practice various En Route scenarios specified by the FAA. Our proposed ATC Scenario Training Technology (ASTT) is currently being developed as a Web-based ERAM training tool, designed to provide a recreation of the ERAM's core functionality with the ability to load/create/modify scenarios. The tool will allow for students to select an instructor-provided scenario and switch between the R-Side and EDST contexts in real time. The challenges of designing such a system are mainly constrained to the team development environment, interface design, scenario simulation, and user response processing domains, but the overall architecture needs to be considered closely. This paper reports on the challenges in designing and developing the underlying ASTT software technology as a computationally intensive and multifaceted system, specifically in the domains of the technology stack selection and development environment creation. ASTT prototype architecture (both front-end and back-end) will also be presented and discussed. In addition, the proposed architecture for project execution will be addressed.

Detect and Avoid (DAA) systems are complex communication and locational technologies comprising multiple independent components. DAA technologies support communications between ground-based and space-based operations with aircraft. Both manned and unmanned aircraft systems (UAS) rely on DAA communication and location technologies for safe flight operations. We examined the occurrence and duration of communication losses between radar and automatic dependent surveillance–broadcast (ADS-B) systems with aircraft operating in proximate airspace using data collected during actual flight operations. Our objectives were to identify the number and duration of communication losses for both radar and ADS-B systems that occurred within a discrete time period. We also investigated whether other unique communication behavior and anomalies were occurring, such as reported elevation deviations. We found that loss of communication with both radar and ADS-B systems does occur, with variation in the length of communication losses. We also discovered that other unexpected behaviors were occurring with communications. Although our data were gathered from manned aircraft, there are also implications for UAS that are operating within active airspaces. We are unaware of any previously published work on occurrence and duration of communication losses between radar and ADS-B systems.

The Federal Aviation Administration's (FAA) Next Generation Air Transportation (NextGen) program is a long-term modernization and transformation of the current National Airspace System (NAS) into a more effective and coordinated decision-making system. NextGen provides a more reliable, secure, and dependable aviation capability for both users and operators ensuring more capacity, throughput, and safety. System Wide Information Management (SWIM) is a NextGen Service Oriented Architecture (SOA) technology that communicates aviation data among the various stakeholders incorporating trajectory based operations and optimum profile descent. SWIM data is delivered to the aircrew via Aircraft Access to SWIM (AAtS) framework.This research paper investigates the information security threats and performance caveats in the main operating components of AAtS by identifying the information security breaches associated with the NAS Enterprise Message Service (NEMS), particularly its data exchange path with Electronic Flight Bag (EFB) through the Data Management Service (DMS). This research addresses the risks associated with the information flow passing through the NAS Enterprise Security Gateway (NESG) internal Data Management Zone (DMZ) and external DMZ. This research delineates the overall strategy for identifying the methodology in testing the data flow from the aircraft EFB via the NEMS network to the external service providers as well as identifying test procedures to emulate the threat vectors on this network. After conducting the necessary tests, the key technical research areas are comprehensively evaluated and recommendations to support the security of the AAtS will be documented.

This paper presents a Research and Development (R&D) effort to design and develop a flight simulation system with Adaptive Surveillance Broadcast (ADS-B), and Traffic Collision Avoidance System (TCAS), for integration of Unmanned Aerial Systems (UAS) into National Airspace System (NAS). The paper will delineate the design and development of the Next Generation Applied Research (NEAR) Lab's FMS (NEAR-FMS) including the UAS aircraft models, and the surveillance simulation equipment. The NEAR-FMS will be used in NextGen projects such as Four-Dimensional Trajectory 4DT operations, as well as Alliance for System Safety of UAS through Research Excellence (ASSURE) projects funded by Federal Aviation Association (FAA). Middle-fidelity Flight Dynamic Models (FDM) of two UASs, a Predator class and a Global Hawk have been designed and tested on JSBSim aerodynamic simulator. Autopilots have been designed and implemented for both UAS FDMs. The paper will present the results of tests on the UAS simulated flights and performance data. The UAS models will be used to test the criticality of the conventional surveillance equipment of the UASs as well as identifying the requirements of these systems for such aircraft. Finally, the assessment of the data generated by the simulated flights will drive the requirements and constraints on the conventional surveillance equipment on the UAS. This project is a work in progress and the detailed results will be published in future publications.

One of the major investments of the Federal Aviation Administration's (FAA) Next Generation Air Transportation (NextGen) program is in Four-Dimensional (4D) Trajectory Based Operations (TBO). The heart of 4D TBO is the autopilot capability on any National Airspace System (NAS) operating aircraft. Autopilot is an essential component of the Flight Management System (FMS), a vital piece in the future automation of the aviation industry. In this research, we propose a simulation-based design of an autopilot for Boeing-737 that can be extended to other types of aircraft. The paper will present the control mechanism in autopilot altitude hold, as well as detailed results of the control loop tests. Multiple tests consisting of diverse maneuvers are simulated to verify the performance of the aircraft. Finally, the autopilot is compared against a conventional autopilot in performing similar maneuvers and the results are displayed. This simulation-based framework allows for cost-effective and risk-free prototyping, verifying, and validating future 4D TBO concepts.

Airspace integration is a major challenge that must be addressed for wider unmanned aircraft system (UAS) acceptance and one-day ubiquitous operations. Both research and training play a role in addressing these challenges, which are cross-disciplinary. Embry-Riddle Aeronautical University (ERAU) is heavily invested in promoting the safe integration of UAS into both the United States National Airspace System (NAS) as well its future under the FAA NextGen programs planned upgrades. This paper surveys ERAUs use of modeling and simulation (M&S) to address the relevant challenges including development of flight management systems (FMS) for UAS to operate amongst manned air traffic, the development of aircraft performance models for various UAS categories, the application of simulator technologies to UAS flight crew training, and the creation of virtual labs to provide realistic training experience for UAS system configuration and testing.

In recent years, there have been important efforts focusing on providing suitable services for mobile networks users and on supporting their increasing demands. One promising standard is called Long Term Evolution Advanced (LTE-A). LTE-A uses different techniques (such as Coordinated Multipoint - CoMP) to deal with bottlenecks to improve performance, in particular for users at the edge of the cells. Here, we show a simulation study focused on the Shared Segmented Upload (SSU) algorithm, which deals with these problems. We use the Discrete Event System Specification (DEVS) formalism to model two different approaches. The simulations show how the SSU algorithm improves services for cell-edge users. We show how to define these kinds of applications using a formal framework like DEVS.

There have been ongoing efforts focused on improving mobile networks standards to support the ever-increasing user demands of high data rate services. These efforts are more crucial for cell-edge users where their long distance from their serving Base Station (BS), and the higher interference from the neighbouring cells, degrades their performance. Contemporary communication standards, proposed for Fourth Generation (4G) of mobile telecommunication standards, use different techniques to deal with these bottlenecks. Long Term Evolution Advanced (LTE-A), is a promising standard for 4G mobile networks, and it uses different technologies to enhance users' performance regardless of their location in the coverage area. LTE-A employs Coordinated Multi-Point (CoMP) technique particularly to provide high data rate services for cell-edge users. In this context, we present Shared Segmented Upload (SSU), a novel method for uploading large files from User Equipment (UE) to multiple BSs in a CoMP communication scenario. We use Discrete EVent System Specification (DEVS) formalism to model an LTE-A mobile network using SSU. In addition, we employ DEVS to simulate a conventional noncooperative algorithm to evaluate the effectiveness of SSU in two scenarios: rural and urban area settings. The simulation results show that, compared to the conventional method, SSU improves cell-edge users' uplink performance and reduces the latency for a UE to upload its data to the network.

Long Term Evolution Advanced (LTE-Advanced) networks have problems of low data rate for cell-edge users, as well as coverage gaps. Contemporary communication standards use different techniques to deal with these problems; one candidate technique is called Coordinated Multi-Point (CoMP). In this context, we introduce Shared Segmented Upload (SSU), a novel method for uploading large files from a UE to multiple BSs in a CoMP communication sce-nario. We use the Discrete Event System Specification (DEVS) formalism to model a mobile network using two approaches: SSU and a conventional non-cooperative algo-rithm. The simulation results show that, compared to the conventional method, the SSU algorithm improves cell edge users' uplink performance and reduces the latency for a User Equipment (UE) to upload its data to the network.

Within the Federal Aviation Administration's (FAA) NextGen project, System Wide Information Management (SWIM) program is the essential core in facilitating the collaborative access to the aviation information by various stakeholders. The Aircraft Access to SWIM (AAtS) is a Service Oriented Architecture (SOA) that provides the technical platform for the exchange of situational information between the aircraft and the National Airspace System (NAS). In this research project, we investigate the challenges in one and two way communication between the Electronic Flight Bag (EFB) and the SWIM network architecture. EFBs are utilized for allowing aircrafts' access to SWIM through a Data Link Service (DLS) provided by a Data Link Service Provider (DLSP). Issues such as cybersecurity, performance, availability, and quality of service in the AAtS are investigated and mitigation approaches toward more secure and efficient service provided to the aircraft and to NAS are discussed. To this end, a set of comprehensive tests are carried out in an emulated network in a lab environment to identify and assess some of the issues associated with quality of service (QoS) as well as cybersecurity in both wired and wireless connectivity of Electronic Flight Bags (EFBs). This work also aims to assess the efficiency of different approaches in the downlink and uplink data transmission between aircraft and the AAtS system. Nine operational scenarios are identified in AAtS, where they are tested with three technical communication scenarios that are further correlated with messaging patterns using web-services.

The System Wide Information Management (SWIM) program is one of the critical components in the Federal Aviation Administration's (FAA) NextGen project. This investigates some of the challenges that arise during communication between the Electronic Flight Bag (EFB) and the Data Management System (DMS). The FAA has identified nine operational scenarios (OS) detailing information exchange within the context of the AAtS between the DMS and the aircraft. The FAA has also identified three technical scenarios (TS) for communication between an aircraft and the DMS for conveying the NAS information. This study is limited to the downlink (information from the aircraft to the DMS) portion of the EFB-DMS interaction. Additionally, we do not investigate NAS-DMS interaction. We implemented a replicated network infrastructure to mimic the functionality of the Aircraft Access to SWIM (AAtS) and the SWIM components relevant to the research. In this environment, the behavior of the entire system is emulated with approximated specifications. We implemented three messaging patterns (MPs), namely, DMS Hosting Request-Response Web Service, DMS Hosting Pub-Sub Service using Java Messaging Service (JMS), and DMS Hosting Pub-Sub with Web Service Notification in the replicated network and tested them against recommended OS-TS combinations. Several message sizes and frequencies of occurrence were used for testing selected combinations. We performed the tests using three different data sizes under full bandwidth contention and no bandwidth contention. Our tests suggest that the selected combinations can work and deliver the desired performance within the available data link bandwidth. The test outcomes also assist in determining which OS-TS-MP combinations are optimal.

Computational Fluid Dynamics (CFD) deals with computing the equations of fluid flows using numerical methods. The Discrete-Event System specification (DEVS) theory has been used to approximate the continuous systems by applying a quantized state system approach. In this research, we employ Cellular DEVS theory (Cell-DEVS) – originally proposed for modeling and simulation of spatial environments – to create a uniform set of rules for CFD. This harmonized set of state changes can effectively render the fluid dynamics, by applying the accurate rule that represents the behavior of the fluid. The combination of the simplicity and the mathematical backbone allows for constructing models computable on an average computer or an array of cluster computers.