Safety Assessment and Risk Estimation for Unmanned Aerial Vehicles Operating in National Airspace System

Xuejun Zhang,Xiangmin Guan,Li Tang,Yu Zhang,Yang Liu,Daniel Delahaye

doi:10.1155/2018/4731585

Abstract

This paper proposes an effective approach for modelling and assessing the risks associated with unmanned aerial vehicles (UAVs) integrated into national airspace system (NAS). Two critical hazards with UAV operations are considered and analyzed, which are ground impacts and midair collisions. Threats to fatalities that result from the two hazards are the focus in the proposed method. In order to realize ground impact assessment, a multifactor risk model is designed by calculating system reliability required to meet a target level of safety for different UAV categories. Both fixed-wing and rotary-wing UAVs are taken into account under a real scenario that is further partitioned into different zones to make the evaluation more precise. Official territory and population data of the operation scenario are incorporated, as well as UAV self-properties. Casualty area of impacting debris can be obtained as well as the probability of fatal injuries on the ground. Sheltering factors are not neglected and defined as four types based on the real scenario. When midair collision fatality risk is estimated, a model of aircraft collisions based on the density of civil flight in different regions over Chinese airspace is proposed. In the model, a relative collision area and flying speed between UAVs and manned aircraft are constructed to calculate expected frequency of fatalities for each province correspondingly. Truthful data with different numbers of UAVs is incorporated in the model with the expected number of fatalities after a collision is included. Experimental simulations are made to evaluate the ground impacts and midair collisions when UAVs operate in the NAS.

Highlights

Unmanned aerial vehicles (UAVs) are a kind of aircraft without pilots onboard but can be remotely controlled or can fly autonomously based on preprogrammed flight plans [1, 2], which is a viable and operational technology in the future [3, 4]
Experimental simulations are made to evaluate the ground impacts and midair collisions when UAVs operate in the national airspace system (NAS)
To develop a preliminary estimate of midair collision risk, the variation of frequency of fatalities spatially over China was investigated, assuming that the UAV was likely to be located from sea level to 50,000 ft, neglecting effects of elevation

Summary

Introduction

Unmanned aerial vehicles (UAVs) are a kind of aircraft without pilots onboard but can be remotely controlled or can fly autonomously based on preprogrammed flight plans [1, 2], which is a viable and operational technology in the future [3, 4]. Risk assessments and estimations of UAVs operating in the NAS become the basement and the first key step. Because it will fundamentally transform existing aviation patterns and its public perceptions. Two critical hazards of UAV operations are taken into account, namely, ground impacts and midair collisions. To estimate the midair collision fatality risk, a model of aircraft collisions based on density of civil flight in different regions over China is proposed. A relative collision area and operating speed between UAVs and manned aircraft are constructed to obtain expected frequency of fatalities for each province using official government data with different numbers of UAVs. Experimental simulations are made to evaluate the ground impacts and midair collisions when UAVs operate in the NAS.

Ground Impact Assessment

Model Simulations

Midair Collision Fatality Risk Estimation

Conclusions