Target Level Of Safety Research Articles

ACAS installation on unmanned aerial vehicles: effectiveness and safety issues

PurposeThe paper aims to investigate the compatibility of manned-aircraft airborne collision avoidance systems (ACAS) for use on unmanned aerial vehicles (UAV).Design/methodology/approachThe paper uses the Fault Tree method for defining ACAS model adapted for the UAV operations, with the aim of showing the presence of certain factors that configure in such ACAS system, and whose failure can lead to an adverse event – mid-air collision.FindingsBased on the effectiveness analysis of ACAS solution adapted for the UAV operations, for given inputs, it can be concluded that the probability of ACAS failure is on the order of 10–4, as well as that in the case of autonomous ACAS solution for the UAV, the probability is reduced to 10–5. The most influential factors for the failure of the UAV’s ACAS are as follows: technical implications on the UAV, human factor, sensor error, communication and C2 link issue.Practical implicationsThe established model could be used both in the UAV’s ACAS design and application phases, with the aim of assessing the effectiveness of the adopted solution. The model outputs not only highlight the critical points of the system but also provide the basis for defining the Target Level of Safety (TLOS) for the UAV operations.Originality/valueThe developed model can be expected to speed up the design and adoption process of ACAS solutions for the UAVs. Also, the paper presents one of the first attempts to quantify TLOS for the UAV operations in the context of collision avoidance systems.

Construction and Research of Safety Management System for Machine Patrol Operation

Aiming at the flight safety problems existing in UAV power patrol inspection, this study proposes a UAV patrol inspection safety management system (SMS) scheme, which takes the safety target level specified in soar as the target management, based on safety management, modern control theory, risk management, and UAV operation regulations, combined with the actual needs of machine patrol inspection of China Southern Power Grid and the requirements of local government. The UAV SMS scheme is developed from four parts: safety policy, risk management, safety guarantee, and safety promotion, and the application analysis is carried out in combination with the Kobe accident case in 2020. The experimental results demonstrate that the implementation of SMS scheme can effectively reduce the accident risk level during UAV power patrol inspection.

Collision Risk Modeling and Analysis for Lateral Separation to Support Unmanned Traffic Management.

This article investigates the utility and extension of well-established collision risk modeling approaches for lateral separation standard development for unmanned traffic management and network design. The applicability of standard assumptions and simplifications made in the manned environment to a scaled-down unmanned aerial systems (UAS) environment is first investigated. The results are used to derive an iso-risk surface that shows the tradeoff between separation distance and navigation performance for a given risk level or target level of safety. The model is then extended to consider collision risk from one to tracks, and finally to determine the total collision risk and the related iso-risk surfaces for systems of parallel tracks with additions to account for the effects of more than two parallel tracks. The extended model is applied to a case study where airspace design for an urban area is conducted via maximization of the number of same-direction parallel tracks while meeting the target level of safety. The results suggest that lateral separation distances less than 100 m are achievable for small UAS, and that the separation standards are mostly affected by the proportion of poorly navigatingaircraft.

제주남단 항공회랑(AKARA-FUKUE Corridor)의 항공안전 개선에 관한 연구

ICAO recommended that airspace monitoring and periodic safety assessments in each Contracting State ensure the stability of the airspace, since reducing the aircraft lateral and vertical separation intervals would rather increase the risk of collision. The target level of safety of the AKARA-FUKUE Corridor at the southern end of Jeju was 247×10^-9. In simple comparison, this means that the risk of an aircraft collision in this area (international safety standards, 5.0×10^-9) is about 50 times higher. The scope of this study is to organize the concept of terms, analyze the air traffic volume, the current status of navigational safety facility usage fees, and investigations of an aircraft collision risk in Jeju southern air corridor. Analyzing government policies and overseas evaluations, revising some of the existing contents, presenting some of the additional contents of new routes, and changing the instrument procedure for Korean-Chinese routes, change of arrive/departure route between Incheon Airport and Shanghai Airport, reduce the risk of aircraft collisions. We hope to restore airspace sovereignty, contribute to policies for the government to take the lead in solving this problem, and expect stability and operational efficiency in air traffic.

Influence of viscous dampers ultimate capacity on the seismic reliability of building structures

Anti-seismic devices should be designed with proper safety margins against their failure, because the reliability of the structural system where they are installed is strongly influenced by their reliability. Seismic Standards generally prescribe safety factors (reliability factors) amplifying the device responses at the design condition, in order to reach a target safety level. In the case of Fluid Viscous Dampers (FVDs), these factors are applied to the stroke and velocity, and their values are not homogeneous among seismic codes.This paper investigates the influence of the values of the safety factors for FVDs on the reliability of the devices and of the structural systems equipped with them. An advanced FVD model is employed to account for the impact forces arising when the dampers reach the end-stroke and the brittle failure due to the attainment of the maximum force capacity. The effect of damper failure on both the fragility and the seismic risk of the structural system is investigated by performing multiple-stripe analysis and monitoring different global and local demand parameters. In particular, a parametric study has been carried out, considering two case studies consisting of a low-rise and a medium-rise steel building, coupled with a dissipative system with linear and nonlinear properties and studying the consequences of different values of safety factors for stroke and forces. The study results give evidence to the potential brittle behaviour of the coupled system and provide information about the relationships between damper safety factors and effective structural reliability. Some preliminary suggestions are given on possible improvements of current design approaches and on the values of the reliability factors to be considered for future code revision.

Development of Shear Resistance Formula for the Y-Type Perfobond Rib Shear Connector Considering Probabilistic Characteristics

A design shear resistance formula for Y-type perfobond rib shear connectors is proposed with the various reduction factors, which can be selected depending on the target safety level. The nominal shear resistance formula is improved based on the systematic sensitivity analysis as well as the regression fit test based on 84 push-out test results, including 15 additional push-out tests to extend the application ranges and reduce the estimation errors, compared to the formula proposed in previous studies. Some design variables are additionally included in the proposed design formula: the yield strengths of rebar and rib plate. The basic design variables in the proposed design formula are (1) number of ribs and transverse rebars, (2) concrete compressive strength, (3) rebar diameter and yield strength, and (4) rib thickness, width, height, and yield strength. The application ranges of the basic design variables are recommended for the proposed design formula. The various shear resistance reduction factors are proposed based on the probabilistic ultimate shear resistance model of Y-type perfobond rib shear connectors. The proposed procedure may be recommended to develop the design formula for shear connectors with various shapes.

OAS Surface Optimization of Shuangliu Airport based on Collision Probability Calculation

Airport clearance safety management is an important part of airport operation indicators. Controlling obstacle height is one of the most important tasks in airport clearance management. The current program design and evaluation in China currently uses the obstacle restriction surface (ILS) and Obstacle Evaluation Surface (OAS). The current program design in our country rarely uses the collision risk mode (CRM), but the obstacles around the airport are gradually increasing. At this stage, the OAS surface is more conservative. A simplified model with a collision probability of approximately 1×10-7 is constructed and compared with the OAS surface to improve it. The results show that the slope of the original OAS surface is larger than that of the simplified model. The improved OAS surface meets the target safety level and solves the problem of being too conservative.

On Probabilistic Risk of Aircraft Collision along Air Corridors

The separation of aircraft in cruising flight in air corridors is based on the assurance of an extremely low probability of collision due to position inaccuracy caused by navigation errors, atmospheric disturbances, or other factors. The appropriate standard is the International Civil Aviation Organization (ICAO) Target Level of Safety (TLS) of frequency of collision less than 5 × 10−9 per flight hour. An upper bound for the collision probability per unit distance is the probability of coincidence, in the case of aircraft flying at the same speed along parallel tracks in the same direction. This leads to the case of two aircraft flying at a constant separation, for which at least three probabilities of coincidence can be calculated: (i) the maximum probability of coincidence at the most likely point; (ii) the cumulative probability of coincidence integrated along the flight path; and (iii) the cumulative probability of coincidence integrated over all space. These three probabilities of coincidence are applied to the old standard and new reduced vertical separations of 2000 ft and 1000 ft respectively, for comparison with the ICAO TLS, and also to assess their suitability as safety metrics. The possibility is raised of complementing the ICAO TLS 5 × 10−9 per hour, which is suitable for the cumulative probability of collision, by two additional safety metrics: (i) one per hour flown squared, which is suitable for comparison with the maximum joint probability density of collision; and (ii) another times hour flown, for comparison with the three-dimensional cumulative probability of coincidence. These three metrics (i) to (iii) have distinct dimensions, give different information, and could be alternatives or supplements.

Lateral collision risk assessment of parallel routes in ocean area based on space-based ADS-B

In order to ensure the safe operation of parallel routes in the ocean area, it is necessary to assess the risk of lateral collision of routes. The data used in the assessment often come from the real flights, while the traditional land-based ADS-B equipment has limited coverage and cannot be used for research. The space-based ADS-B system can receive and send the flight position of the aircraft over the ocean area. In this paper, the ocean tracks in space-based ADS-B data are first extracted. According to the different route structures, the data of fixed route and flexible route are preprocessed by segmented Kalman filter and cubic polynomial fitting method respectively. Then the processed track position error is calculated, and Q-Q (Quantile-Quantile) median method is used to test the normal distribution of the error, and k-means clustering is used to obtain the clustering center and occurrence frequency of positioning error and flight error. Finally, a collision risk model based on Bayesian network is established, and the error distribution parameters and occurrence frequency are brought into the model to evaluate the collision risk of parallel routes in the ocean area. The results show that the lateral collision risk based on space-based ADS-B ocean flight data is lower than 0.5 × 10−8 times/hour specified by ICAO when the fixed route separation is 14n miles and the flexible route separation is 49n miles. And the actual lateral interval of the Pacific flexible route is 50n miles (Jiang, 2010), which meets the safety target level.

Study on the Operation Safety and Reliability of a Waxy Hot Oil Pipeline with Low Throughput Using the Probabilistic Method.

When the hot oil pipeline is running at a low throughput, it easily enters into an unstable condition, which seriously threatens the safety of the hot oil pipeline operation. In this study, the unsteady heat transfer and flow mathematical models for the hot oil pipeline system were established first by comprehensively considering the uncertainty of parameters during pipeline operation, such as the operating parameters (throughput and oil temperature), physical properties of crude oil (freezing point, viscosity, and thixotropic parameters), and environmental parameters (buried deep soil temperature and soil thermal conductivity). Then, the efficient Latin hypercube sampling (LHS) stochastic numerical algorithm was applied and further developed to quantitatively describe the operation safety of hot oil pipelines with low throughput in the form of probability. On the basis of the abovementioned research, the qualitative relationship between pipeline flowrate and friction loss is obtained. Finally, taking an actual crude oil pipeline as an example, the failure probabilities of the pipeline under different operating conditions were analyzed in detail. Combined with the target safety level of pipeline operation, the minimum allowable throughput of pipelines was determined. This study revealed the flow and heat transfer law of hot oil pipelines with low throughput and determined its operation safety and reliability under different operating conditions.

Empirical study of airport geofencing for unmanned aircraft operation based on flight track distribution

With the increasing activities of unmanned aircraft (UA) near airports, severe challenges have emerged regarding airport safety management. This paper presents a brand-new data-driven based approach to accurately design the geofencing for UAs around an airport, focusing on midair collision risk between commercial flights and small UAs which is considered as the most important hazard. In premise, prevalent trajectory extraction from real flight tracks is realized based on an advanced and general model, taking the advantage of describing turning legs which is more popular in terminal area. As a key solution, a Gauss-Laplace-composite distribution is provided for rigorous estimation of flight track distribution in line with the extracted prevalent trajectory. Based on those, airport geofencing is proposed consisting of an inner critical area and an outer buffer area. This approach can be adaptive for different traffic patterns of an airport. The buffer area is an extension range to help the execution of some defense measures. Results of an empirical study for setting up geofencing for small UAs around Chongqing Jiangbei International Airport (ZUCK) show the superiority of the proposed approach, which indicates that it can provide practical application, especially varying from different target level of safety.

Runway Veer-Off Risk Analysis: An International Airport Case Study

Runway excursions are the main risk for runway safety: operational protection areas mitigate the effects of events classified as veer-off, overrun, and undershoot. This paper presents a methodology for the quantitative risk assessment of runway veer-off in an international airport whose name will not be revealed for privacy reasons. The proposed methodology is based on similar principles adopted in other aviation risk analyses. The Real Level of Safety (RLS) related to the veer-off accident was calculated through the implementation of a retrospective analysis that permits to define a frequency model, a location model and a consequence model. Instead, Target Level of Safety (TLS) was defined through the risk matrix and acceptability criteria present in the International Civil Aviation Organization (ICAO) Safety Management Manual. Finally, the risk of veer-off accidents in the airport under evaluation was determined by using primary data provided by the airport management body. Risk values were calculated in more than 1300 points around the runway and they were used to assess the current level of safety. The authors present a risk map that allows identifying the areas in the strip with the highest risk of a veer-off accident. The obtained results demonstrate that the developed methodology represents a useful tool to define TLS and to assess whether infrastructural and operational modification need to obtain the required level of safety.

Enhanced reliability assessment of punching shear resistance models for flat slabs without shear reinforcement

Punching shear is one of the main failure mechanisms in flat slabs. To prevent such failures, modern structural codes, as EN 1992-1-1, offer design provisions against punching shear. However, these provisions were calibrated based on experience, which can affect the precision of the resulting safety level. The use of modern reliability analysis techniques is required for a more precise evaluation of the safety level of these structural systems. This paper presents a comprehensive review of the state-of-the-art of reliability techniques where the safety level of design provisions for punching shear resistance without shear reinforcement is investigated. This study addresses three reliability analysis techniques: Mean-Value First Order Second Moment Method (MVFOSM), First-Order Second Moment Method (FOSM) and a Monte-Carlo simulation with Importance Sampling (MC-IS). Reliability indices β are used as a practical measurement of the safety level representing probabilities of failure. The parameters influencing the punching shear capacity without shear reinforcement were varied that the area of practical interest is covered. The estimated reliability indices β are evaluated and compared to a target safety level given by EN 1990 for a 50-year reference period where β is equal to 3.8. The results seem to confirm that the punching shear provisions for slabs without shear reinforcement according to EN 1992-1-1 achieve a required safety level, which is in accordance to the target level given by EN 1990. In addition, the study shows that the use of the techniques FOSM and MC-IS seems appropriate for determining the probability of failure of the design equation for the punching shear capacity without shear reinforcement. Furthermore, the study suggests that the method MVFOSM may not be suitable to assess the absolute safety level of such design equations. Finally, the study highlights the potential of using the aforementioned reliability analysis techniques and stresses the importance of modelling the uncertainties for a precise structural safety assessment of flat slabs without shear reinforcement.

Проблемы и перспективы формирования системы проактивного мониторинга безопасности работников предприятий горнодобывающей отрасли

The analysis of official statistics shows that the existing mechanisms for reducing the risks of occupational injuries, based on monitoring traditional indicators of occupational safety, and financing a set of appropriate preventive measures, largely exhausted their potential. They do not contribute to further formation of a stable trend to reduce the occupational injuries. The phased abandonment of prescriptive regulation in the industry of the Russian Federation makes it inevitable to introduce the concept of the goal of activities on ensuring occupational safety and health. Approaches to managing safety of the organizational processes when measuring the efficiency of the occupational health and safety management system should be based on active monitoring and continuous improvement of the performance indicators of the relevant processes. The relevance and need for a comprehensive solution of the theoretical, methodological and applied problems of monitoring efficiency in the field of ensuring safety of employees labor in the industry of the Russian Federation, as well as the imperfection of the scientific and methodological base and the state system of the operative management of occupational risks require the development of adequate and efficient solutions for improving the level of occupational safety, reduction of deaths and injurie rate. The essence of the concept of proactive monitoring of safety is that the efficiency of planning and monitoring in the field of ensuring safety at all levels (state, industry, corporate, etc.) should be justified using measurable indicators (indices) of the efficiency of ensuring safety and corresponding values of the target and threshold safety levels. The paper focuses on the problems of developing a proactive monitoring system for occupational safety, and the use of leading indicators for monitoring occupational safety and health state in real time, as well as to respond appropriately.

Feasibility Study on Independent Instrument Approach Operations between Runways 36L/18R and 01/19 at Beijing Capital International Airport

Beijing Capital International Airport is one of the busiest hub airports in the world, but its capacity is limited. Reducing the minimum radar interval during instrument approaches would be feasible to increase capacity. The airport has three parallel runways; the distance between runways 36L/18R and 01/19 is 3.485 km. Currently, because there is no final monitoring seat, the dependent parallel instrument approach mode is adopted on the two runways; approaching aircraft must maintain a 4 km safety separation. This paper focuses on whether the 4 km radar safety separation for parallel instrument approaches could be reduced to 3.485 km without the final monitoring. This would mean implementing independent instrument approach operations between the two runways. To consider this, a new collision risk model based on position error probability and aircraft kinematics is proposed. A test program to acquire data on controllers’ reaction times in abnormal situations was designed and implemented over 10 days by the North China Air Traffic Management Bureau (ATMB). Furthermore, six months of radar trajectory data was collected at the airport. This was analyzed and processed to obtain the position error, speed, and other parameters required for the calculation of the collision risk model. The results show that the independent instrument approach operations between runways 36L/18R and 01/19 would be feasible the within safety target level set by the International Civil Aviation Organization (ICO). Based on the theoretical research results, the North China ATCB implemented independent instrument approaches between runways 36L/18R and 01/19 on December 25, 2018; it has operated safely since.

Adequate fire safety for structural steel elements based upon life-time cost optimization

Structural fire safety requirements implicitly balance up-front investments in materials (protection or element sizing) with improved performance (loss reductions) in the unlikely event of a fire. For traditional prescriptive fire safety recommendations, the underlying target safety levels are not clear to the designer, nor is the associated balancing of risk and investment costs.It is discussed that traditional (structural) fire safety design is deterministic, with the safety foundation premised upon the collective experience of the profession. However, it is noted that building forms are increasingly uncommon in nature, due to material choice, height, failure consequences, etc. Within the framework presented in PD 7974–7:2019 there is an expectation that probabilistic risk assessment (PRA) methods be employed to demonstrate adequate safety for cases where the collective experience of the profession cannot be called upon to guide design approaches. In doing so, any design must be demonstrated to be tolerable to society, and the residual risk as low as is reasonably practicable (ALARP).In support of the PD 7974–7:2019 framework, the paper assesses the failure probabilities of isolated steel elements in function of insulation thickness, utilization, load ratio and (mean) fire load. In support of a generalized definition of target safety levels for structural fire safety engineering, optimum target safety levels for insulated steel beams are then determined as a function of the fire characteristics by applying life-time cost optimization (LCO) techniques. The LCO results in an assessment of the optimum investment level as a function of the fire, and damage and investment cost parameters characterizing the building. It is intended that the current contribution can be a steppingstone towards rational and validated reliability targets for performance-based design (PBD) in structural fire safety engineering.

A survey of regional citrate anticoagulation for emergency continuous renal replacement therapy

To investigate the status of regional citrate anticoagulation (RCA) in continuous renal replacement therapy (CRRT) in emergency department. Participants of a national emergency conference from August 1st to August 4th in 2019 from hospitals of different levels in different regions were interviewed by online questionnaire to collect data about the current status and limitations of the application of RCA in emergency CRRT by convenient sampling. Totally 407 questionnaires were collected through internet, and the completeness of the answers was as high as 100%. Twenty-three responses with logic errors were excluded, and 384 questionnaires were finally retrieved, with an effective rate of 94.35%. Representatives from 29 provinces, autonomous regions and municipalities directly under the Central Government participated in the questionnaire survey, and the hospitals in which they worked were mainly class III grade A [70.31% (270/384)]. The survey showed that 61.46% (236/384) of the emergency departments could carry out CRRT independently. There were less than 10 CRRT cases per month in most emergency departments [52.87% (166/314)]. In the emergency departments where CRRT were carried out, heparin was a widely used and well-applied anticoagulant [82.17% (258/314)], and 199 emergency departments (63.38%) were proficient in RCA. In clinical practice, heparin [49.68% (156/314)] was preferred to RCA [25.80% (81/314)] and low molecular weight heparin [23.56% (74/384)]. In the emergency departments where RCA could be used skillfully, 4% sodium citrate was the main regional anticoagulant [68.34% (136/199)]. Anticoagulation protocol came from different sources, most of which were from nephrology or dialysis center (29.65%). Most departments could adjust the ionized calcium before the filter to the target safety level [0.9-1.2 mmol/L, 88.94% (177/199)], and adjust the ionized calcium after the filter to the target ideal anticoagulation level [0.2-0.4 mmol/L, 93.47% (186/199)] within 4 hours. The common complications that emergency physicians concerned were accumulation of citrate [58.29% (116/199)], metabolic alkalosis [54.77% (109/199)] and metabolic acidosis [37.19% (74/199)]. In 281 emergency departments that could not use RCA, there were kinds of factors that limited the use of citrate, such as higher cost than heparin (31.67%), unskilled personnel (21.00%), limited source of citrate (17.08%), concerns of complications (11.74%). At present, the substitution fluids used in clinical practice were mainly the commercial products (45.54%). In most cases, emergency CRRT filters had a life span of 12-23 hours (39.49%). The use of RCA in domestic emergency CRRT is low. Compared with the international peers, we are still lacking of adequate understanding of RCA. Therefore, it is necessary to develop an anticoagulation protocol of RCA for emergency departments in China, and promote training of CRRT.

Safe RPAS integration in non-segregated airspace

Purpose This paper aims to assess the implications in safety levels by the integration of remotely piloted aircraft system (RPAS). The goal is to calculate the number of RPAS that can jointly operate with conventional aircraft regarding conflict risk, without exceeding current safety levels. Design/methodology/approach This approach benchmarks a calculated level of safety (CLS) with a target level of safety (TLS). Monte Carlo (MC) simulations quantify the TLS based on the current operation of conventional aircraft. Then, different experiments calculate the CLS associated with combinations of conventional aircraft and RPAS. MC simulations are performed based on probabilistic distributions of aircraft performances, entry times and geographical distribution. The safety levels are based on a conflict risk model because the safety metrics are the average number of conflicts and average conflict duration. Findings The results provide restrictions to the number of RPAS that can jointly operate with conventional aircraft. The TLS is quantified for four conventional aircraft. MC simulations confirm that the integration of RPAS demands a reduction in the total number of aircraft. The same number of RPAS than conventional aircraft shows an increase over 90% average number of conflicts and 300% average conflict time. Research limitations/implications The methodology is applied to one flight level of en-route airspace without considering climbing or descending aircraft. Originality/value This paper is one of the most advanced investigations performed to quantify the number of RPAS that can be safely integrated into non-segregated airspace, which is one of the challenges for the forthcoming integration of RPAS. Particularly, Europe draws to allow operating RPAS and conventional aircraft in non-segregated airspace by 2025, but this demanding perspective entails a thorough analysis of operational and safety aspects involved.

Reliability of Steel Truss Roof Systems Under Variable Snow Load Profiles

The probabilistic safety analysis of steel truss roof systems under variable snow load profiles is investigated. The roofs of structures such as industrial buildings or sports halls, which require wide areas, are frequently subjected to unexpectedly high loads. Therefore, compared to the residential buildings, that type of buildings often comes across failure or prohibition of usage. Probabilistic techniques are utilized for the analysis of the problem. Thirty-six steel roof structures with different structural dimensions and load variations are modelled and their failure probabilities are calculated. In this paper, a complicated stochastic analysis is reduced to the solution of a load–resistance (S–R) problem by utilizing sensitivity analyses. Firstly, the structures were designed through structural analyses, and then the sensitivity analyses were conducted to understand the response of the structure to the load and to the span-length parameters. In this paper, a reliability study which gradually monitors the effect of geometrical parameters on the failure trend is presented. Three different snow load distribution functions were used. The relation between failure, and load or structural dimension variations was investigated. The results obtained in this study are discussed and compared with the results from the literature for similar structures subjected to snow loads. It is observed that for the snow load distributions with high standard deviations the structural reliability indices may give results below the target safety levels of the design codes. Finally, the assessment of the results shows that the effect of the standard deviation of the snow load on failure probability is much more than the effect of intensity of the nominal snow load.

Third-Party Risk Analysis of Small Unmanned Aircraft Systems Operations

Small unmanned aircraft systems (sUASs) are widely used in various applications, and their traffic will increase as the field of operations becomes varied. Increased traffic will potentially involve a higher possibility of conflicts between sUASs, and midair collisions can occur when the risk of conflicts is not fully mitigated by detect-and-avoid capabilities. Therefore, third-party risk should be assessed, especially for urban airspace. This paper proposes a methodology for the assessment of third-party risk due to midair collisions between sUASs. As a worst-case scenario of sUAS operations in urban airspace, this paper uses the proposed model to analyze the third-party risk in a central business district in a metropolitan city. The results show that third-party risk is not acceptable for the given traffic scenario. Based on these results, several methods are suggested to reduce the third-party risk and satisfy the target level of safety. In addition, the results shown in this paper can be used as references for certificates of operation and/or mitigation devices for sUASs. The main contribution of this paper is to build a third-party risk model that takes into account midair collisions between sUASs and the energy loss during impact.