Assessing the Effect of ADS-B Message Drop-Out in Detect and Avoid of Unmanned Aircraft System Using Monte Carlo Simulation

Abstract

This work analyzes the severity and risk associated with automatic dependent surveillance-broadcast (ADS-B) message drop-out in detect and avoid (DAA) function of unmanned aircraft systems (UAS). Performance assessment of the universal access transceiver (UAT) ADS-B message implies that, in some cases, ADS-B fails to update within a specified update interval, which is referred to as ‘drop-out’ in this work. ADS-B is a fundamental surveillance sensor for both class 1 and class 2 DAA systems. Message loss or drop-out has been found as one of the common limitations of the ADS-B system. The key feature of this study is incorporating the update rate of real ADS-B data transmitted from the manned aircraft. The data were received from the Grand Forks International Airport, North Dakota. Monte Carlo method has been adopted to resolve encounter scenarios in the presence of drop-out. The change in the alert triggered by the UAS DAA in the presence of ADS-B drop-out has been investigated. Furthermore, the risk matrices are created to quantify the associated risk with drop-out affected alerts. Simulation results depict that both the duration of drop-out and DAA look-ahead time affect the alert-triggering function of UAS. With a small look-ahead window and longer duration of drop-out, the number of warning alerts increases. Also, alerts are affected more during an overtaking encounter than that of a head-to-head encounter. A system-level analysis is also carried out to recognize the potential reasons behind the ADS-B drop-out.

Analyzing Sense and Avoid Requirements to Integrate Unmanned Aircraft Systems into Controlled Airspace

“…Proceedings of the International Conference on Industrial Engineering and Operations Management Manila, Philippines, March 7-9, 2023 © IEOM Society International as successful avoidance maneuvering is deterministic and verifiable in nature. In their study, Tabassum and Semke found that ADS-B message drop-out to presented a hazardous or catastrophic outcome with ≤ 120 second look-ahead time at an incidence rate of 1.7935×10 -5 to 1.5140×10 -6 (Tabassum & Semke, 2018). A proposed pulse-Doppler radar for detection of non-cooperative aircraft with a beamwidth of 140° would provide for a probability of failed detection of non-cooperative aircraft of 3.88×10 -3 in a head-on scenario.…”

“…The majority of events in the study fell into the category of accepted risk with mitigation, concluding that "with the provision of ATC [Air Traffic Control] interation and possible multi-sensor fusion", the risks of UAS integration could be appropriately mitigated (Tabassum & Semke 2018). Though it provides a thorough surveillance picture adaquate for UAS sense-and-avoid applications when operating as intended, ADS-B message drop-out presents a significant enough risk that complimentary sensors to detect non-cooperative aircraft are required.…”

“…Local ADS-B performance has been recorded and analyzed at a number of low-and high-density aerodromes in an attempt to quanitfy its reliability (Syd Ali 2013;Tabassum & Semke 2018;Hicok & Lee 1998). In their 2018 study using data collected at Grand Forks International Airport, North Dakota, Tabassum and Semke concluded that ADS-B drop-out presented a remote probability of an unacceptable risk of an intruding aircraft violating what is defined as 'well-clear', UAS separation minima defined by Special Committee-228 and the FAA and summarized in Table 2…”

“…Representing a generational leap from its transponder predecessors, ADS-B allows for a complete and automatic air surveillance picture, updated in near real-time, and allows for direct aircraft-to-aircraft communication (International Civil Aviation Organization 2014). Despite its numerous advantages, ADS-B reliance presents potentially significant risk: failed message delivery referred to as 'drop-out' risk fracturing surveillance picture accuracy (Fang & Zan 2011;Tabassum & Semke 2018). In addition, detection probability of non-cooperative aircraft and lost-link logic, particularly in BLOS operations, must be carefully examined to ensure that UAS integration introduces no significant level of risk not already present in current VFR operations.…”

Research on ADS-B spoof detection technology based on radio spectrum features

“…The ADS-B technology is based on an airborne navigation system and an airborne broadcast transmitter system, combined with corresponding receiving equipment, to provide surveillance services to the ATC system [9][10]. The application provided by ADS-B contains two types, ADS-B OUT and ADS-B IN, i.e., transmitting and receiving.…”