The analysis approach is consistent with an accident analysis (as in a Safety Analysis
Report) that defines an approximate level of risk, rather than a detailed risk assessment.
Thus, it adopts the typical accident analysis practice of addressing uncertainty through the
use of analytical margin (i.e., conservatism) instead of through a formal uncertainty
analysis. The philosophy is not one of providing substantial margin in every parameter
used in the approach, as the combination of these margins would yield a final result so
conservative as to be totally useless. Instead, margin is provided in each parameter
based on the standard development team's judgement of the level of uncertainty in the
parameter and the level of margin needed to address the uncertainty. Adjustments were
made to assure that the level of margin provided at each step and throughout the process
as a whole is adequate and reasonable.
When applied as a complete approach, the methodologies in this standard will result in a
technically justified, conservative analysis of the risk posed by releases resulting from
aircraft crash. The risk will be defined at a sufficient level of detail to document the safety
of the facility with respect to aircraft crash, and at the same level of detail as would be
expected for other types of accident analyses. The standard will also be sufficient to
support safety findings, decision making, and design, and will free the user from justifying
the techniques and models used in the assessment. However, it is not the intent of this
standard to imply that these are the only methodologies acceptable for such an
assessment. Alternative methodologies that meet the intent of the standard may be
proposed and used, but their acceptability needs to be assessed on a case-by-case basis.
Purpose. This is an analytical standard intended to provide a sound, technically justifiable,
and consistent approach to analyzing the risk posed by an aircraft crash into a facility
containing radioactive or hazardous chemical materials. The focus is on analyzing the risk
posed to the health and safety of the public and onsite workers from a release of
hazardous material following an aircraft crash. Thus, this is not a standard on aviation
safety and does not consider the risk to the occupants of the aircraft; the risk to individuals
inside a building affected by the crash itself; or the risk to other individuals on the ground,
either inside or outside a facility boundary, who might be directly impacted by the crash.
This focus forms the basis for the standard's assumptions about excluding the