# Holographic Mixed Reality System for Air Traffic Control and Management
## 2 Literature Review  
Air traffic control is a very hectic and sensitive job. Many researchers have worked on making this job easier to perform. Approximately 25 years ago, [PERSON], a member of the Federal Aviation Administration (FAA), proposed the idea of performing tasks in air traffic control towers using augmented reality technology [3]. A prototype was not made at that time, although many researchers recalled [PERSON] surmising various methods that could facilitate controllers [4]. In 1996, an advanced interface for the human-computer interaction for air traffic management was presented  
Figure 1: The virtuality continuum. by [PERSON] et al. [5]. Moreover, another concept under scrutiny is the development of remotely located air traffic services. This is based on a rendering of a recreated 360\({}^{\circ}\) tower view in real time in virtual reality [6; 7; 8; 9]. Many researchers have investigated 3D interfaces and compared them with 2D interfaces based on the controllers' performance with air traffic management systems [10; 11; 12]. In 2010, [PERSON] et al. proposed a 4D interface rendered over a 2D screen for better interpretation of flight data by controllers [13]. For early detection of conflicts among flights, that study proposed a method to evaluate and display the airplanes in their future locations. In 2014, [PERSON] et al. did a flight test to measure the registration error in the use of augmented reality within the control tower [14]. They observed errors in the registration due to the latency in the airplanes' surveillance transport. In 2015, another method based on rendering the 3D information of flight data on 2D displays was proposed by [PERSON] et al. [15]. They also targeted the provision of better interaction paradigms to air traffic controllers using more focused visuals for better understanding of flights around the control tower. In 2016, [PERSON] et al. also proposed an augmented reality-based method for air traffic control towers [16]. They presented a rendering pipeline for multiple head-up displays to overlay outside views of the control tower with a visual symbol representing the location of an airplane outside the tower. In the same year, [PERSON] et al. introduced a virtual reality-based immersive control tower and investigated future challenges as well as multiple scenarios for the air traffic control system [17]. In September 2016, [PERSON] et al. evaluated various augmented reality systems for the assessment of their application to on-site control towers [18]. In their project, they concentrated on the placement of the airplanes' information in the windows of the air traffic control tower. In 2017, [PERSON] et al. presented a discussion on the development of a prototype that could merge real-time ground radar information on the airplanes with the airplanes in captured images from a live IP camera [19]. In addition to the support of augmented reality for an air traffic control and management system, [PERSON] et al. also developed an augmented reality-based interface for supporting joint air tactical controllers [20]. All of the existing systems discussed above played a vital role in enhancing the performance of air traffic controllers. However, there are still many limitations in terms of better human-computer interaction in air traffic management services. The three-dimensional interfaces provided to visualize the traffic in an airport still use 2D screens for rendering [13; 15; 19]. Compared to conventional approaches, these methods have significantly improved the performance of air traffic controllers. However, due to the use of 2D displays for rendering 3D information, the interpretation power of controllers is still limited. Until now, no efficient and interactive interface has been provided for visualizing the radar data of traffic in the air. However, virtual reality-based immersive systems [17] also did not perform well because there was less confidence by the controller in a virtual environment disconnected from the outer world.