Editor's note: This article uses the terminology regarding safety barriers and mitigations as used in "Operational Safety Study: Risk of operation without a transponder or with a dysfunctional one, by EUROCONTROL SISG"

Introduction

Generally, two types of safety barriers exist – prevention barriers and mitigation barriers. The former are used to minimize the risk of an occurrence happening and the latter are intended to eliminate or reduce the impact of an event after it has happened.