## 2 Safety and Human Errors in Aviation  
Safety in the aircraft industry is currently defined as \"the state in which the possibility of harm to persons or of property damage is reduced to, and maintained at or below, an acceptable level through a continuing process of hazard identification and safety risk management\" [2]. In ICAO Annex 19 [8], the Safety Management System (SMS) assumes two phases for increasing air transport safety. Phase 1 has the main goal of eliminating the common causes of accidents, mostly related to technology, training, and procedures, among others; it is also expected to manage organizational causes. ICAO and the regulators know that eliminating the risk is an impossible task; the purpose is to detect errors by safety barriers, especially designed to prevent them from going unnoticed. With this approach it is intended to keep the risk level very low; should it even so go up, mitigation measures must be ensured [8]. The evolution of the SMS through time is shown in Figure 1.  
Actions implemented in Phase 1 to handle Technical Factors were usually the introduction of better and more reliable technology, related with the technical evolution of aircraft systems. As to Human Factors, workload limitations were often implemented. In what concerns organizational factors, the actions taken were the introduction of active SMS departments focused on personal and organizational risk mitigation. An SMS is a top-down, organization-wide philosophy, that manages and controls the risk of all subjects related with the air transport. It assumes four basic pillars [8]:  
1. Safety policies. It must be a proactive system that looks to identify possible risks that can compromise safety before they happen. 2. Risk management. When these risks are identified, they must be properly assessed and actions must be taken to keep the risk as low as possible. 3. Risk Performance Assessment. Tools and Keep Performance Indicators (KPI) must then be developed to better manage and visualize the safety goals for the whole organization. Figure 1: The evolution of the SMS through time. Quality and Safety Assurance. From the monitoring of the KPI's, actions must be deployed to mitigate, or at least to bring again to very low levels, the risk or any potential threat to the air transport safety. These actions sometimes identify new threats, requiring new actions that must be deployed. To have success in this, a safety culture must be implemented in the entire organization. All persons and existing processes must be engaged therewith. One individual alone can compromise the entire safety culture process, if not engaged with its goals. Automated processes and actions can be an effective solution to increase safety and lower the risk, but the downside is that humans tend to rely too much on them and lower their guard, leading again to a risk increase for unidentified threats. To better assess the types of risks, the risk matrix in Table 1, which helps to categorize all types of hazards, was developed. Red, yellow and green identify, respectively, what is unacceptable under any type of circumstance, what is tolerable with the implementation of risk mitigation actions, and the acceptable region. [PERSON] [9] identified two types of approaches regarding errors. One is the personal approach, where the focus is solely on individual characteristics, such as personal moral weakness, forgetfulness, and distraction. In this vein, for instance, refs. [10; 11; 12] concluded that, in general aviation (i.e., civil flights excluding commercial activity), pilot gender has no bearing on whether accidents result in injuries, and that the same happens with age, as the increase in experience compensates for the more challenging flights that older pilots undertake. The other is the system approach, where the focus lies on the conditions promoting human error, with the intention of building layers of defense to manage risk and mitigate hazards, resulting in a safety management model. According to this approach, for instance, [PERSON] et al.