This appendix provides the information and guidance necessary to implement the frequency
calculation methods described in Chapter 5 of the standard.
Determination of Number of Operations. The first factor in determining the aircraft impact
frequency, F, is the number of annual aircraft flight activities, N, near the site under
consideration. Because of the different ways in which flight operations are conducted,
aircraft flight activities are tabulated differently for the airport environment and the
In the airport environment, aircraft flight activities may be tabulated in terms of aircraft
operations or airport operations. The analyst may have to use data concerning either
aircraft operations or airport operations or both to derive a value for N. Aircraft
operations, as defined by the Federal Aviation Administration (FAA), include the arrivals
at and departures from an airport at which an airport traffic control tower is located.
Airport operations are defined as either local or itinerant. Local airport operations are
flights in which the aircraft flies to a nearby airport or performs simulated approaches to
the airport. Also classified as local operations are those which include aircraft that
(1) operate in the local traffic pattern or within sight of the airport, (2) are known to be
departing for or arriving from practice areas located within a 22-mile radius of the airport,
or (3) execute simulated instrument approaches or low passes at the airport. All other
airport operations are classified as itinerant operations. Itinerant operations are basically
flights which land at the airport after a trip from somewhere else, or take off from the
airport for a trip elsewhere. For both itinerant and local airport operations, each takeoff,
landing, or approach without landing is an operation. For historical data on airport
operations at airports with FAA control towers, the analyst should obtain the document,
FAA Air Traffic Activity, distributed by the FAA Office of Aviation Policy, Plans and
Management Analysis each fiscal year.
For the nonairport environment, values for the NPf(x,y) product have been determined.
If additional information is needed, the analyst should consult the ACRAM Modeling