Chapter 18 FAA Risk Hazard Analysis

The FAA is regularly revising their UAS Risk and Hazard analysis scoring methods. A recent report published the following risk matrix (Figure 18.1). The FAA defines safety risk as the composite of predicted severity and likelihood of the potential effect of a hazard.

Recently Published Risk Matrix from the FAA

Figure 18.1: Recently Published Risk Matrix from the FAA

18.1 Hazard Severity

The FAA defines severity as the consequence or impact of a hazard’s effect or outcome in terms of degree of loss or harm.

  • Minimal severity refers to outcomes in which a UAS causes discomfort to those on the ground.

  • Minor severity refers to outcomes in which a UAS causes non-serious injury to three or fewer people on the ground.

  • Major severity refers to outcomes in which

    • a UAS causes non-serious injury to more than three people on the ground;
    • a UAS crew experiences a reduced ability to cope with adverse operating conditions to the extent that there would be a significant reduction in safety margins; or
    • a UAS causes a manned aircraft to make an evasive maneuver, but the UAS and the manned aircraft remain greater than 500 feet apart.

  • Hazardous severity refers to outcomes in which

    • the UAS crew is incapacitated;
    • a UAS flies within 500 feet of a manned aircraft; or
    • a UAS causes injury to persons other than the UAS crew.

  • Catastrophic severity refers to outcomes in which

    • a UAS collides with a manned aircraft or
    • a UAS causes a fatality or fatal injury to one or more persons other than the UAS crew.

18.2 Likelihood

The FAA defines likelihood as the estimated probability or frequency in quantitative or qualitative terms of a hazard’s effect or outcome.

  • Frequent - at least once per week.
  • Probable - less than once per week and at least once per 3 months.
  • Remote - less than once per 3 months and at least once per 3 years.
  • Extremely Remote - less than once per 3 years and at least once per 30 years.
  • Extremely Improbable - less than once per 30 years.

18.3 Analysis

The Risk Matrix in Figure 18.1 can be utilized to determine whether or not a particular hazard requires mitigation. It also provides insight to the FAA’s safety approach.

Observations:

  • The FAA labels a UAS-manned aircraft as a catastrophic incident and that it is only tolerable without mitigation if it occurs less frequently than once per 30 years.
  • The FAA labels equivalent risk severity for injury a spectator as a UAS flying within 500 ft of a manned aircraft.
  • Injuring a member (or three) of the UAS crew is considered a minor severity and any hazard that may cause it to happen more frequently than once per 3 years recommends mitigation.