# A Novel Intelligent IoT System for Improving the Safety and Planning of Air Cargo Operations
## 1 Introduction  
Since its conceptualization in the early 1980s, the Internet of Things (IoT), has revolutionized the way people work, move, trade, communicate or even live. During the last decade, concepts such as smart cities [1], smart factories [2], or smart agriculture [3] are part of our daily lives with a great impact on circular production [4] and blue growth [5], among others. Furthermore, advances in technologies such as 5G and parallel processing as well as data analysis techniques (i.e., machine learning, deep learning) enable the design and operation of large-scale digital manufacturing processes [6] and digital twins, even of an entire city [7]. A comprehensive review of the current state of the art of the IoT is provided in [8], while an overview of architectures and applications of industrial IoT (IioT) is critically presented in [9]. As a vital cell for international trade and economic development [10], the aviation industry provides USD 3.5 trillion in world economic activity which accounts for 4.1% of the global gross domestic product [11]. Focusing on its efficiency, optimization, and safety enhancement, the industry is gradually moving to the Industry 4.0 era [12]. Unit load devices (ULDs) are an integral component of air cargo operations. The International Air Transport Association (IATA) states that approximately 1 million aircraft ULDs are in service globally [13]. It provides the only rapid worldwide transportation network,which is vital to many industries' global supply chains, used primarily to transfer time-sensitive goods. Fast delivery is essential to businesses that provide streamlined production processes or that rely on the urgent delivery of parts for machinery and equipment [11]. While in the last two decades, a large number of solutions have been presented aiming at secure and efficient transportation of hazardous or high-value cargo in the railway [14], ground transportation [15], and the shipping [16] industry, similar efforts in the aviation industry are limited. Technologies such as digital twin [17] have been introduced, but they are mainly focusing on cargo load planning and optimization [18; 19], introducing RFID technology for ULD identification and monitoring (e.g., [20; 21]), due to the high impact of the ULD operations on the delivery cost. However, the occurrence of accidents regarding cargo transportation is alarmingly high. According to the International Air Transport Association (IATA) [22], ULD is one of the most common causes of aircraft damage among all ground operations. The utilization of batteries is particularly perilous, being inflammable. More than 100 incidents related to battery ignition in cargo holds have been reported since 2019, prompting the Federal Aviation Administration (FAA) to present a new regulation imposing the use of fire suppressant ULDs, to avert potential life-threatening emergencies [23]. The European Union Aviation Safety Agency (EASA) in the latest accident report [24], included the cargo handling risk among the major risks in the industry. Furthermore, in a recent report on the impact of COVID-19 in the aviation industry by EASA [25], it was emphasized that systems enabling ULD status monitoring are crucial for cargo handling and the elimination of human mistakes. Although there are examples of studies developing frameworks for remote monitoring and cargo handling [26], structural health monitoring approaches [27; 28; 29], and intelligent systems for fire detection [30; 31], to the best of the authors' knowledge, the currently available solutions do not comprehensively support remote monitoring and control of the container parameters regarding their structure, status, location, fire and smoke warning indication. In this regard, recognizing its necessity, through its project called \"Interactive Cargo\" [32], IATA targets establishing a new regulatory regime to enable the use of connected devices to monitor the transported cargo.