Error containment improves as the severity of operational errors (OEs) increases, according to a U.S. Federal Aviation Administration (FAA) study of events involving U.S. en route air traffic controllers.1 But looking at the OE data strictly by risk categories masks some error containment inefficiency.
The report describes two different studies of OEs. The first concerned the probability of resolution (POR); the second, the effects of the controller’s time on position (TOP).
Study 1 was described as measuring “OE containment.” The FAA Air Traffic Organization (ATO) classifies OEs into four risk categories in increasing order of severity: proximity events, in which 90 percent or greater separation is retained either horizontally or vertically; Category C, or low risk; Category B, or moderate risk; and Category A, or high risk. The ATO calculates the rates of Category B and Category A OEs to monitor progress toward safety goals.
