The National Academies

ACRP 04-18 [Final]

Runway Protection Zone (RPZ) Risk Assessment Tool

  Project Data
Funds: $400,000
Research Agency: Applied Research Associates
Principal Investigator: Jim Hall
Effective Date: 6/4/2014
Completion Date: 7/11/2016


The FAA has identified a number of critical safety areas that airports need to maintain to specific standards to protect aircraft, passengers, people, and property. The runway safety area (RSA) is one such area that is designed to protect aircraft utilizing the runway. The runway protection zone (RPZ) is designed to enhance the protection of people and property on the ground.
The FAA recommends that the RPZ is clear of structures and people, but activities occur within a RPZ at airports for any number of reasons, some of which are beyond the control of the airport. For example, the introduction of GPS approaches can increase the size of the RPZ that had previously been maintained, thus introducing activities into the RPZ that were once outside.
ACRP Report 3: Analysis of Aircraft Overruns and Undershoots for Runway Safety Areas looked at data related to overrun and undershoot accident and incidents. ACRP Report 50: Improved Models for Risk Assessment of Runway Safety Areas  developed a risk analysis related to obstacles in or near the vicinity of the RSA. Airports also need to understand the risks of activities that occur within the RPZ so they can develop mitigation strategies, amongst other planning activities.
The objectives of this research are to develop (1) a tool for airports that will assess the risk (a) of an aircraft accident in a RPZ and (b) based on the output in the first analysis, assess the risk to people and property based on a density measure, and land use; and (2) a users’ guide. Airports will use the output from both sections of the tool to develop mitigation strategies as part of their overall planning process.  The first part of the tool will assess the probability of an aircraft accident in the RPZ, and should be based on (1) a quantifiable risk analysis of accidents and incidents that have occurred in RPZs within the United States and relevant international data within the last 20 years; (2) an analysis of historical trends of accidents relative to the RPZ both within the U.S. and internationally for the past 20 years; and, (3) other factors that influence the risk analysis, such as weather, geography, topography, type of approach, aircraft type, type of operations, and so on. Airports will use the second part of the tool to determine the severity of the risk to people and property for a specific RPZ. The airport will input two sets of data in the second part: site-specific factors as identified in the first part, and the range of density measures, land uses, and any other relevant factors.
The users’ guide should include at a minimum:
  • General overview on risk assessment, risk tolerance, and how to use the information;
  • How this tool can be used as part of an SMS;
  • How to use both parts of the tool;
  • How to interpret the results;
  • An outline of the steps necessary to use the output of the tool to develop mitigation strategies;
  • Identification of the variables that are relevant to determining the risk to lives and property that will be needed to use the tool;
  • A case study or example that illustrates how to the tool can be used and the application of results; and
  • Additional resources, as appropriate.
STATUS: This has been published ACRP Report 168: Runway Protection Zone (RPZs) Risk Assessment Tool Users' Guide as well as the RPZ_RAT Tool that can also be downloaded. The Contractor's Final Report is also available on how the research was conducted and an explanation of the methodology.

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