The interpretation is simple; however, it is sometimes misleading. That an event is expected
to occur in 1 year does not mean that the event will take at least 1 year to occur. The event
may occur today or it may be many years before it happens. The period is an average period if
the time to obtain the data was long enough to measure the frequency of occurrence and the
conditions remained the same. When reviewing the number of accidents on the ramp over a
period of 15 years, an airport found that 18 accidents had occurred in that period, as shown in
Table H-2.