I received a question from someone interested in what literature might be available for understanding the FAA’s risk criteria for expected casualties (Ec —pronounced “E sub c”), and how Ec is calculated.
One of the best ways to understand an agency’s regulations is to read the two preambles that accompany the regulations. You can find preambles in the Federal Register. You will find the FAA’s commercial space transportation regulations at Title 14 of the Code of Federal Regulations, Chapter III. Chapter III applies to FAA licensing, permitting, and the regulation of launch and reentry vehicles and the operation of launch and reentry sites, and contains parts 400 through 460. Part 420 contains the requirements for a licensed launch site operator. Part 460 applies to human space flight. Other parts apply to expendable launch vehicles, reentry, enforcement, and financial responsibility.
An explanatory preamble accompanies an agency’s proposed new rules. Another preamble, which also discusses any comments the agency received from the public, accompanies the agency’s release of its final rules. For Ec, there are now a number of preambles that help to understand those calculations.
If you just want to understand what Ec is, the discussions of the risk requirements in part 420 for launch sites—aka spaceports—are a great place to start because they discuss two simplified versions of the calculations and thus make a good primer for newbies. The notice of proposed rulemaking for 14 C.F.R. part 420 is here. The final rule and disposition of comments is here. Do be aware that these are early versions of the FAA’s risk requirements, and the FAA made changes later, and apply to persons applying for a license to operate a launch site. Launch operators must look elsewhere.
A launch operator of expendable launch vehicles (ELVs) will be more interested in the risk requirements of 14 C.F.R. part 417, and an operator of a reentry vehicle, including reusable launch vehicles (RLVs), will find its risk criteria in parts 431 and 435.
The FAA recently changed its risk requirements for ELVs, RLVs and spaceports. The agency proposed to do so in this notice of proposed rulemaking. It released the final version of the new regulations and a discussion of the comments it received in this final rule. When you are reading recent documents such as these, note the references to earlier notices of proposed rulemaking and final rules. You may find discussions there that explain something the new regulations don’t address.
Practitioner’s Note: When referring to the FAA’s space regulations in their entirety, do refer to 14 C.F.R. ch. III. Do not refer to them as 14 C.F.R. part 400. Part 400 only contains two sections, and there are many more parts.