The 90-day performance tolerance standard assessment was prompted by a review at New York Tracon conducted last year that revealed some small operational-error violations on final approach that were detected by later examination of radar records. Controllers are not being assessed an operational error on final approach if aircraft separation is inadvertently reduced from 3 nm to 2.7 nm (excluding larger separation standards for heavies). The FAA emphasized that the assessment is not being done with the idea of changing the 3-nm separation, but rather to determine the fairness of charging controllers with an operational error for a small technical violation when there was no safety risk. The existing practice of charging controllers with an operational error encouraged controllers to “buffer” their separation to 3.5 or 4 nm to ensure they would not go under 3 nm and risk being charged with an operational error. It is a routine that the FAA believes results in lost capacity.