The most basic tool is the risk matrix.  [Figure 4-1]  It assesses  two items: the likelihood of an event occurring and the  consequence of that event. Every flight has hazards and some level of risk associated  with it. Pilots must recognize hazards to understand the risk  they present. Knowing that risk is dynamic, one must look  at the cumulative effect of multiple hazards facing us. It is  critical that pilots are able to: Likelihood is nothing more than taking a situation and  determining the probability of its occurrence. It is rated as  probable, occasional, remote, or improbable. For example, a  pilot is flying from point A to point B (50 miles) in marginal  visual flight rules (MVFR) conditions. The likelihood of  encountering potential instrument meteorological conditions  (IMC) is the first question the pilot needs to answer. The  experiences of other pilots coupled with the forecast might  cause the pilot to assign “occasional” to determine the  probability of encountering IMC.  The following are guidelines for making assignments. For the pilot who is part of a flight crew, input from  various responsible individuals cancels out any personal  bias or skewed judgment during preflight planning and the  discussion of weather parameters. The single pilot does not  have the advantage of this oversight. If the single pilot does  not comprehend or perceive the risk, he or she will make  no attempt to mitigate it. The single pilot who has no other  crewmember for consultation must be aware of hazardous  conditions that can lead to an accident. Therefore, he or she  has a greater vulnerability than a pilot with a full crew.  Assessing risk is not always easy, especially when it involves  personal quality control. For example, if a pilot who has been  awake for 16 hours and logged over 8 hours of flight time  is asked to continue flying, he or she will generally agree  to continue flying. Pilots often discount the fatigue factor  because they are goal oriented and tend to deny personal  limitations when asked to accept a flight. This tendency  is exemplified by pilots of helicopter emergency medical  services (EMS) who, more than other pilot groups, may make  flight decisions based upon the patient’s welfare rather than  the pilot’s personal limitations. These pilots weigh intangible  factors such as the patient’s condition and fail to quantify  actual hazards appropriately, such as fatigue or weather, when  making flight decisions.  Examining National Transportation Safety Board (NTSB)  reports and other accident research can help a pilot learn to  assess risk more effectively. For example, the accident rate  during night visual flight rules (VFR) decreases by nearly  50 percent once a pilot obtains 100 hours, and continues to  decrease until the 1,000 hour level. The data suggest that for  the first 500 hours, pilots flying VFR at night might want to  establish higher personal limitations than are required by the  regulation and, if applicable, become better skilled at flying  under instrument conditions.  Several risk assessment models are available to assist the pilot  in determining his or her risk before departing on a flight.  The models, all taking slightly different approaches, seek  the common goal of assessing risk in an objective manner.  The other item in the matrix is the severity or consequence  of a pilot’s action(s). It can relate to injury and/or damage. If  the individual in the example above is not an instrument flight  rules (IFR) pilot, what are the consequences of encountering  inadvertent IMC conditions? In this case, because the pilot is  not IFR rated, the consequences are potentially catastrophic.  The following are guidelines for this assignment. Figure 4-1.  A sample risk assessment matrix a pilot can use to  differentiate between low-risk and high-risk flights.  Catastrophic Critical Marginal Negligible Improbable Remote Occasional Probable Risk Assessment Matrix Likelihood Severity Serious Low Medium Serious Serious High High High • Negligible—less than minor injury, less than minor  system damage • Marginal—minor injury, minor damage • Critical—severe injury, major damage • Catastrophic—results in fatalities, total loss •  Improbable—an event is highly unlikely to occur.  • Remote—an event is unlikely to occur, but is possible. •  Occasional—an event will probably occur sometime. •  Probable—an event will occur several times. Severity of an Event Likelihood of an Event Quantifying Risk Using a Risk Matrix •  Differentiate, in advance, between a low-risk flight  and a high-risk flight. •  Establish a review process and develop risk mitigation  strategies to address flights throughout that range. 4-2