Methodology for Impact Frequency Screening

DOE-STD-3014-96

Nijk

estimated annual number of site-specific aircraft operations (i.e.,

takeoffs, landings, and in-flights) for each applicable summation

parameter (no./y);

Pijk

aircraft crash rate (per takeoff or landing for near-airport phases and

per flight for the in-flight (nonairport) phase of operation for each

applicable summation parameter;

fijk(x,y) =

aircraft crash location conditional probability (per square mile) given

a crash evaluated at the facility location for each applicable

summation parameter;

Aij

the site-specific effective area for the facility of interest that includes

skid and fly-in effective areas (square miles) for each applicable

summation parameter, aircraft category or subcategory, and flight

phase for military aviation (see Appendix B);

(index for flight phases): i=1, 2, and 3 (takeoff, in-flight, and landing);

(index for aircraft category or subcategory): j=1, 2,..., 11;

(index for flight source): k=1, 2,..., K (there could be multiple

runways, and nonairport operations);

;

site-specific summation over flight phase, i; aircraft category or

ijk

subcategory, j; and flight source, k.

It should be noted that there is uncertainty associated with the frequency estimates

produced using the four-factor formula, caused by the need to model complex physical

processes using parameters that are based upon limited historical data.

Experience-based judgements have been made as needed to supplement historical data,

introducing additional uncertainties. This standard does not provide a quantitative

estimate of the uncertainties involved; rather, the mathematical formulations and

supporting parameter estimates have been made so as to provide a

reasonable point estimate of the frequency of aircraft crash impacts into specified

facilities.

5.2

Methodology for Impact Frequency Screening. Although the desirability of a simple

impact frequency screen based on the number of operations at nearby airfields was