The ABCs of OEZs: Understanding Spaceport Camden’s Safety Criteria

Last week the Tribune & Georgian printed some excerpt of emails exchanged between Camden County and property owners on Little Cumberland Island regarding Land Hazard Areas, overflight exclusion zones and their potential to close and/or require evacuations of Cumberland Island and Little Cumberland Island.

This blog post will explain how these terms are used in the Code of Federal Regulations, the steps Camden County has taken to identify overflight exclusion zones and Land Hazard Areas, the due diligence the County has undertaken to ensure a variety of companies can launch from Spaceport Camden and our efforts to ensure property owners on Cumberland Island and Little Cumberland Island can remain on their property during launches.

A BASELINE UNDERSTANDING OF SAFETY CRITERIA IN THE CODE OF FEDERAL REGULATIONS

Launches from Spaceport Camden are generally governed by several separate sections of the Code of Federal Regulations (CRF).  The license to operate Spaceport Camden, the license Camden County is seeking, is known as a launch site operators license (LSOL).  LSOL’s are governed by 14 CFR 420.

Before any launch company (Vector, ABL, SpaceX etc.) can launch a rocket from Spaceport Camden, they must also receive a license from the FAA pursuant to 14 CFR 415 and meet the launch safety criteria outlined in 14 CFR 417.  There are other sections of the CFRs that govern licenses for re-entry of various objects as well, but are not addressed here as they do not impact our discussion topic.

Therefore, in order to have a successful spaceport, you need to be sure your launch site meets the requirements of 14 CFR 420 before you can get a license and you want to be sure potential customers can pass the safety criteria in 14 CFR 417.

There are some terms that seem the same but have different definitions within the CFR.  To make them clear, we have highlighted them below.

Overflight Exclusion Zone (OEZ) – This term is found in 14 CFR 420. The flight corridor will include an OEZ “where the public risk criteria of 1 * 10-4 would be exceeded if one person were present in the open.”

Land Hazard Area– This term is found in 14 CFR 417 where the FAA notes for a land mass “a launch operator may initiate flight only if the risk to any individual member of the public does not exceed a casualty expectation of 1 * 10-6 for each hazard.”

***Note, this is a similar, but 2 orders of magnitude more stringent requirement to meet than the OEZ requirement (which is 1 * 10-4).

So now that we have a baseline understanding of the safety criteria and the terminology in the Code of Federal regulations let’s take a look at how this all applies to Spaceport Camden.

ALLOWABLE OEZ CALCULATION METHODS AND FINDINGS

Within 14 CFR 420, there are two appendices, A and B that describe example methods to define a flight corridor, and a subset of the flight corridor called the OEZ.  Neither of these appendices are required to be used by an applicant, as noted in 14 CFR 420.23(a)(3) that states:

Uses one of the methodologies provided in appendix A or B of this part. The FAA will approve an alternate method if an applicant provides a clear and convincing demonstration that its proposed method provides an equivalent level of safety to that required by appendix A or B of this part.

Spaceport Camden has elected to use a quantitative method of calculating the Overflight Exclusion Zone for a specific launch vehicle and trajectory.  Spaceport Camden contracted with The Aerospace Corporation, a private company that utilizes using specialized algorithms and models to performs various safety related analyses including calculating the OEZ areas.

The Aerospace Corporation performs these analyses for many parts of the US Government and private entities. For Spaceport Camden, The Aerospace Corporation calculated the flight corridor and OEZ pursuant to the quantitative requirements of 14 CFR 420.23(a)(1) and (2), respectively and found that the OEZ does not reach Little Cumberland Island or Cumberland Island for the largest planned rocket to be flown from Spaceport Camden.

As noted earlier, the OEZ is just one of two exclusion areas that ultimately need to be determined.  While Spaceport Camden is only required to calculate the OEZ to obtain its license from the FAA, potential customers will need to calculate, among other things, a Land Hazard Area for their individual launches.  Therefore, The Aerospace Corporation was further tasked to perform the safety analysis required for launch operators under 14 CFR 417 to ensure the safety of the public and that future customers could reasonably obtain a launch license from Spaceport Camden.

Spaceport Camden is not required to perform this 14 CFR 417 individual risk analysis to gain a launch site operators license, however, we wanted to be sure companies could launch from Spaceport Camden without requiring property owners to leave their property on Cumberland Island or Little Cumberland Island. Again, no Land Hazard Areas were identified on Cumberland Island or Little Cumberland Island for a representative medium-large launch vehicle (the size of a Falcon 9 rocket); the largest planned size rocket to be launch from our site.

ASSUMPTIONS IN OUR CALCULATIONS

Because the Aerospace Corporation calculated the OEZ and Land Hazard Areas using specialized algorithms and models we have received inquiries and feedback asking if Spaceport Camden used liberal assumptions (such as census records that show zero population on Little Cumberland Island, or assuming homeowners to shelter inside “bunkers”,  or rocket failure rates below the range specified in the Draft EIS) to achieve these favorable results.  Nothing could be further from the truth.

In fact, Spaceport Camden used highly conservative assumptions.  Here are just a few examples:

  • For one launch, we assumed a launch trajectory of 83 degrees. This is a flight path that makes little sense commercially due to the science and math of orbital mechanics because you can get to the same orbit flying a little southeast (away from Little Cumberland Island, as flying a little northeast over Little Cumberland Island.  But it is a very conservative trajectory assumption because it flies over the most amount of people, and hence drives up the calculated risk results.
  • We assumed the largest launch vehicle that will be launched at Spaceport Camden, a medium-large rocket similar to a SpaceX Falcon 9 or United Launch Alliance Atlas V.
  • We assumed every structure on Little Cumberland Island was inhabited 24 hours a day, 7 days a week, 365 days per year.
  • We assumed all population on Little Cumberland Island were located outside, in the open air, not inside any structure or hardened shelter.
  • We assumed a rocket failure rate well in excess of the 2.5%-6% rate specified in the EIS.

Even with these conservative assumptions, Spaceport Camden launch trajectories passed the Aerospace Corporation safety analysis.

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