C U.S. Department of Transportation Federal Aviation Administration Advisory Circular Subject: Population Exposure Analysis AC No: 450.123-1
Date: 10/12/2022 Ini tiated By: AST-1
This Advisory Circular (AC) provides guidance and a comprehensive method for performing a population exposure analysis as part of a Flight Safety Analysis (FSA) in accordance with Title 14 of the Code of Federal Regulations (14 CFR) 450.123. In accordance with § 450.123(a), a flight safety analysis must account for the distribution of people across the entire region where there is a significant probability of impact of hazardous debris. In accordance with § 450.123(b), the exposure analysis must (1) characterize the distribution of people both geographically and temporally; (2) account for the distribution of people among structures and vehicle types; (3) use reliable, accurate, and timely source data; and (4) account for vulnerability of people to hazardous debris effects. In its application, an operator must submit a description of the methods used to develop the exposure input data and complete population exposure data, in tabular form, in accordance with § 450.123(c).
The Federal Aviation Administration (FAA) considers this AC an accepted means of compliance for complying with the regulatory requirements of § 450.123. It presents one, but not the only, acceptable means of compliance with the associated regulatory requirements. The contents of this document do not have the force and effect of law and are not meant to bind the public in any way. The document is intended only to provide clarity to the public regarding existing requirements under the law or agency policies.
If you have suggestions for improving this AC, you may use the Advisory Circular Feedback form at the end of this AC.
Michael J. O’Donnell, A.A.E.
Deputy Associate Administrator, AST-2 (A) FAA, Office of Commercial Space Transportation
Contents Paragraph Page
1 Purpose1
2 Applicability2
3 Applicable Regulations and Related Documents3
4 Definition of Terms5
5 Acronyms6
6 Flight Safety Analysis7
7 Use of Population Exposure Analysis in Flight Safety Analysis8
7.1 Identify Regions of Interest8
7.2 Transit Modes8
7.3 Population Categories9
7.3.1 Personnel Involved in S upporting a Launch or Reentry9
7.3.2 Neighboring Operations Personnel (NOP)10
7.3.3 Public10
8 Population Exposure Analysis – C onstraints11
8.1 Characterize Distributions of People Geographically and Temporally11
8.1.1 Geographical Distributions of People11
8.1.2 Temporal Distributions of People16
8.2 Sheltering18
8.2.1 Important Factors18
8.2.2 Characterizing Buildings19
8.2.3 Characterizing Motor Vehicles21
8.2.4 Characterizing Waterborne Vessels21
8.2.5 Characterizing Other Vehicles21
8.2.6 Characterizing Structures for Building-by-Building Modeling21
8.2.7 Characterizing Sheltering in Near-facility Areas22
8.2.8 Characterizing Sheltering in Larger Regions22
8.3 Input Data Sources23
8.3.1 Site Operator Data23
8.3.2 Completeness of Databases24
8.3.3 On-Facility Data24
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Contents (continued) Paragraph Page
8.3.4 Spectator Areas28
8.3.5 Near-Facility Population Data29
8.3.6 Offshore Oil Rigs Population30
8.3.7 Large-Region Population Data31
8.3.8 Process for Data Maintenance34
8.3.9 On-facility and Near-facility Data34
8.3.10 Large Region Data34
8.4 Accounting for Vulnerability of People35
8.5 Ensuring Documentation, Traceability, and Configuration Management35
9 Population Exposure Analysis - Application Requirements36
9.1 Description of Methods36
9.2 Complete Population Exposure Data36
9.2.1 Structure Classes36
9.2.2 Population Data36
9.3 Variable Population Data37
Figures Number Page
Figure 1. Population Data Resolution as a Function of Dispersion12
Figure 2. Near Facility Population Data Example14
Figure 3. Example of Downrange Population Center Areas16
Figure 4. Survey Example for Building Data Sheet25
Figure 5. Survey Example for Section Data Sheet26
Figure 6. Survey Example for Floor Data Sheet27
Figure 7. Example Vehicle Volume per Hour Data30
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Contents (continued) Paragraph Page Tables Number Page
Table 1. Data Collected for Beaches near Launch Site17
Table 2. Building Classes for Inert Debris20
Table 3. Building Classes for Explosive Debris20
Table 4. Example of EC for Varying Population Sizes in a Viewing A rea28
Table 5. Comparison of Data Sources for Quantifying Populations at Risk32
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1 PURPOSE.
This Advisory Circular (AC) provides guidance and methods for performing a population exposure analysis in accordance with Title 14 of the Code of Federal Regulations (14 CFR) 450.123. This AC is not mandatory and does not constitute a regulation. This AC describes an acceptable means, but not the only means, for performing a population exposure analysis as part of a flight safety analysis.
1.1 Analysis Scope.
An operator’s flight safety analysis method must account for all reasonably foreseeable events and failures of safety-critical systems during nominal and non-nominal launch or reentry that could jeopardize public safety, in accordance with § 450.115(a). In accordance with § 450.123(a), a flight safety analysis must account for the distribution of people for the entire region where there is a significant probability of impact of hazardous debris. In § 45 0.123(a), the standard of “significant” means that the scope of the population exposure analysis is bounded by what is necessary to demonstrate compliance with the risk criteria in § 450.101(a) and (b), consistent with the scope and methods requirements set forth in §§ 450.113 a nd 450.115.
1.2 Description of Methods.
Section 450.123(c)(1) requires an applicant to submit a description of the methods used in the population exposure analysis, in accordance with § 450.115(c). For a population exposure analysis, physical surveys or other empirical data should be considered benchmark conditions. The results from well-validated high fidelity population models can qualify as a valid benchmark. Section 450.115 (c) requires the identification of:
• The scientific principles and statistical methods used;
• All assumptions and their justifications;
• The rationale for the level of fidelity;
• The evidence for validation and verification required by § 450.101(g);
• The extent to which the benchmark conditions are comparable to the foreseeable conditions of the intended operations; and
• The extent to which risk mitigations were accounted for in the analyses.
1.3 Level of Imperatives.
This AC presents one, but not the only, acceptable means of compliance with the associated regulatory requirements. The FAA will consider other means of compliance that an applicant may elect to present. In addition, an operator may tailor the provisions of this AC to meet its unique needs, provided the changes are accepted as a means of compliance by the FAA prior to application acceptance in accordance with § 450.35(a)(1). Throughout this document, the word “must” characterizes statements that directly follow from regulatory text and therefore reflect regulatory mandates. The word “should” describes an option that, if used would constitute a means to comply with the regulation; variation from the provisions of this AC is possible, but must satisfy the regulation to constitute a means of compliance. The word “may” describes variations or alternatives allowed within the accepted means of compliance set forth in this AC.
2 APPLICABILITY.
2.1 The guidance in this AC is for launch and reentry vehicle applicants and operators required to comply with part 450. The guidance in this AC is for those seeking a launch or reentry vehicle operator license, a licensed operator seeking to renew or modify an existing vehicle operator license, and FAA commercial space transportation evaluators.
2.2 The material in this AC is advisory in nature and does not constitute a regulation. This guidance is not legally binding in its own right, and will not be relied upon by the FAA as a separate basis for affirmative enforcement action or other administrative penalty.
Conformity with this guidance document (as distinct from existing statutes and regulations) is voluntary only, and nonconformity will not affect rights and obligations under existing statutes and regulations. This AC describes acceptable means, but not the only means, for demonstrating compliance with the applicable regulations.
2.3 The material in this AC does not change or create any additional regulatory requirements, nor does it authorize changes to, or deviations from, existing regulatory requirements.
3 APPLICABLE REGULATIONS AND RELATED DOCUMENTS.
3.1 Applicable United States Code (U.S.C.) Regulation.
• 51 U.S.C. Subtitle V, Chapter 509.
3.2 Related FAA Commercial Space Transportation Regulations.
The following 14 CFR regulations should be accounted for when showing compliance with § 450.123. The full text of these regulations can be downloaded from the U.S.
Government Printing Office e-CFR. A paper copy can be ordered from the Government Printing Office, Superintendent of Documents, Attn: New Orders, P.O. Box 371954, Pittsburgh, PA, 15250-7954.
• Section 450.31(a)(6), General Requirements to Obtain a Vehicle Operator License.
• Section 450.101, Safety criteria.
• Section 450.113, Flight safety analysis requirements – scope.
• Section 450.115, Flight safety analysis methods.
• Section 450.117, Trajectory analysis for normal flight.
• Section 450.119, Trajectory analysis for malfunction flight.
• Section 450.121, Debris analysis.
• Section 450.135, Debris risk analysis.
• Section 450.137, Far-field overpressure blast effects analysis.
• Section 450.139, Toxic hazards for flight.
• Section 450.187, Toxic hazards mitigation for ground operations.
3.3 Related FAA Advisory Circulars.
FAA Advisory Circulars are available through the FAA website, http://www.faa.gov.
Some of these are not yet published.
• AC 450.101-1A, High Consequence Event Analysis, dated May 20, 2021.
• AC 450.107-1, Hazard Control Strategies Determination, dated July 27, 2021.
• AC 450.108-1, Flight Abort Rule Development, dated July 27, 2021.
• AC 450.115-1A, High Fidelity Flight Safety Analysis, dated June 24, 2021.
• AC 450.115-2, Medium Fidelity Flight Safety Analysis, when published.
• AC 450.117-1, Trajectory Analysis for Normal Flight, dated August 19, 2021.
• AC 450.119-1, Trajectory Analysis for Malfunction Flight, when published.
• AC 450.137-1, Distance Focusing Overpressure Risk Analysis, when published.
• AC 450.139-1, Toxic Risk Hazard Analysis and Mitigations, when published.
3.4 Technical Reports Related to Population Exposure Analysis.
1. Allahdadi, Firooz A., Isabelle Rongier, Tommaso Sgobba, and Paul D. Wilde, Safety Design for Space Operations, Sponsored by The International Association for the Advancement of Space Safety, (Watham, MA, Elsevier, 2013).
2. Bureau of Transportation Statistics, “Number of U.S. Aircraft, Vehicles, Vessels, and Other Conveyances,” 2021. https://www.bts.gov/content/number-us-aircraftvehicles-vessels-and-other-conveyances
3. Florida Department of Transportation, “Statewide Traffic Impacts”, 2020.
4. Larson, Erik, Large Region Population Sheltering Models for Space Debris Risk Analysis, American Institute of Aeronautics and Astronautics (AIAA) Atmospheric Flight Mechanics Conference and Exhibit, Report #2005-6322, (San Francisco, CA:
AIAA, August 2005).
5. Oak Ridge National Laboratory, “LandScan, Geographic Information Science and Technology”, 2018. https://landscan.ornl.gov/
6. Range Commanders Council, Risk Committee, Range Safety Group, Common Risk Criteria for National Test Ranges, RCC 321-10, (White Sands, NM: RCC, 2010).
7. Socioeconomic Data and Applications Center (SEDAC), “Gridded Population of the World (GPW), v4, CIESIN, (New York, New York: Columbia University, 2020). https://sedac.ciesin.columbia.edu/
8. United States Census Bureau, “Explore Census Data”, 2020.
https://data.census.gov/cedsci/ Note: The industry documents referenced in paragraph 3.4 of this AC refer to the current revisions or regulatory authorities’ accepted revisions.
4 DEFINITION OF TERMS.
For this AC, the terms from § 401.7 and the following definitions apply:
4.1 Flight Safety Analysis (FSA) A quantitative evaluation of the risks to people and critical assets addressing both normal flight and malfunctions of the launch vehicle and safety-critical systems.1
4.2 Population Center A geographic region over which the variation in risk, for each class of individuals, is not significant either because the probability of casualty or the probability density of people is nearly uniform.
4.3 Sheltering The distribution of people among structures and vehicle types, which affects their vulnerability to hazardous debris.
1 Under part 450, there are 11 performance-based sections with FSA requirements that fall into three groups. The first group, §§ 450.113 and 450.115, provides requirements on the scope and fidelity of the analyses required by the remaining nine sections. The second group, which consists of five sections from §§ 450.117 through 450.131, specifies the requirements for analyses necessary to develop quantitative input data used by the last four sections.
The last group consists of four sections that specify quantitative risk analyses with products necessary to evaluate compliance with the safety criteria in § 450.101. All of the FSA sections must use methods that comply with § 450.101(g) because they are essential to demonstrating compliance with the safety criteria in § 450.101.
5 ACRONYMS.
AC – Advisory Circular AST – FAA Office of Commercial Space Transportation CEC – Conditional Expected Casualties CFR – Code of Federal Regulations DFO – Distance Focusing Overpressure EC – Collective Risk FAA – Federal Aviation Administration FFBO – Far-Field Blast Overpressure FSA – Flight Safety Analysis GDP – Gross Domestic Product GPW – Gridded Population of the World (on-line database) IIP – Instantaneous Impact Point km – kilometer MPL – Maximum Probable Loss NASA – National Aeronautics and Space Administration NOP – Neighboring Operations Personnel PEMB – Pre-Engineered Metal Building RCC – Range Commanders Council U.S. – United States U.S.C. – United States Code 6
6 FLIGHT SAFETY ANALYSIS.
Launch and reentry flight safety analysis is a process that is inherently dependent on using models and model parameters to simulate the consequences of vehicle failures and the resulting hazardous events, which must account for the distribution of people both geographically and temporally in accordance with § 450.123(b)(1). A population exposure analysis should define a set of scenarios that describe all of the possible distributions of people sufficiently to produce a valid determination of risk using accurate source data from demographic sources, physical surveys, or other methods.
The flight hazard area analysis must account for the regions of land, sea, and air potentially exposed to hazardous debris generated during normal flight events and all reasonably foreseeable failure modes, in accordance with § 450.133(a)(1), and all reasonably foreseeable events and failures of safety-critical systems during nominal and non-nominal launch or reentry that could jeopardize public safety, in accordance with § 450.115(a). The population exposure analysis produces input data that is necessary for the flight safety analyses. The population exposure analysis must account for the distribution of people among structures and vehicle types, use reliable, accurate, and timely source data, and account for vulnerability of people to hazardous debris effects in accordance with § 450.123(b)(2) through (b)(4).
Note: In accordance with §§ 450.137, 450.139, and 450.187, a population exposure analysis must also be used to provide input to other public risk analyses to address toxic hazards and far-field overpressure blast effects, if any. Applicants should refer to AC 450.137-1 Distance Focusing Overpressure (DFO) Risk Analysis, AC 450.139-1, and Toxic Release Hazard Analysis for guidance on those topics.
7 USE OF POPULATION EXPOSURE ANALYSIS IN FLIGHT SAFETY ANALYSIS.
Section 450.123(a) requires the flight safety analysis to account for the distribution of people for the entire region where there is a significant probability of impact of hazardous debris. This requirement is accomplished by performing a population exposure analysis. This analysis results in a quantitative model of the location of people, which varies spatially and accounts for different time periods. The model is often based on data from numerous sources and typically aggregates people into population centers. A population center could be as small as a section of a building or as large as several thousand square kilometers (km).
7.1 Identify Regions of Interest.
As a first step, a population exposure analysis must identify the entire region where there is significant probability of impact of hazardous debris, in accordance with § 450.123(a). The standard of “significant” means that the scope of the population exposure analysis is bounded by what is necessary to demonstrate compliance with the risk criteria in § 450.101(a) and (b), consistent with the scope and methods requirements set in §§ 450.113 and 450.115. The region should consider all types of hazardous debris (as defined in § 401.7), which accounts for hazards from explosive and toxic substances, as well as potential for consequences due to either planned operations (e.g. jettisons) or reasonably foreseeable failures. The extent of the region should always include, at a minimum, the region enclosed by hazardous debris impact points corresponding to flight abort limits (extending with a hazard footprint buffer; see AC 450.108-1). To analyze risks of the failure of a flight abort system (if present) or if there is no active abort system, an operator should identify a region that covers any portion of the Earth where hazardous debris could impact. The extent may be defined by the region where the individual probability of casualty exceeds 1x10-14 for individuals in any shelter category.2 For a suborbital vehicle, the extent may be defined by the region that encompasses the maximum range of the vehicle’s worst-case instantaneous impact point (IIP).
7.2 Transit Modes.
The exposure model should also include people in all types of transit vehicles other than aircraft; including ships, boats, autos, buses, trains, and trucks; in accordance with § 450.101(a)(1) and (b)(1). People in aircraft are excluded from the collective risk (EC) requirements of § 450.101(a)(1) and (b)(1) and people in spacecraft are accounted for by compliance with § 450.169, which discusses launch and reentry collision avoidance.
These modes are especially important in areas near the launch/landing site. It is also important to appropriately account for waterborne vessels because the vulnerability of people on waterborne vessels can be quite different than it is on land.
2 The individual probability of casualty limit comes from the sufficiency to meet the 1E-4 EC criteria. 1E-14 comes from the potential of the entire world (global population) being exposed (such as for random reentry). 1E-14 is a little smaller than 1E-4 / Global Population.