14 CFR § 234.8 - Calculation of on-time performance codes.
(a) Each reporting carrier shall calculate an on-time performance code in accordance with this section and as provided in more detail in accounting and reporting directives issued by the Director, Office of Airline Information. The calculations shall be performed for each reportable flight, except those scheduled to operate three times or less during a month. In addition, each reporting carrier shall assign an on-time performance code to each of its single plane one-stop or multi-stop flights, or portion thereof, that the carrier holds out to the public through a CRS, the last segment of which is a reportable flight.
(b) The on-time performance code shall be calculated as follows:
(1) Based on reportable flight data provided to the Department, calculate the percentage of on-time arrivals of each nonstop flight. Calculations shall not include discontinued or extra-section flights for which data are not reported to the Department.
(2) Based upon the on-time performance percentage calculated in paragraph (b)(1) of this section, assign a single digit code to each flight that reflects the percentile of on-time performance achieved by the flight, as set forth in the following table:
On Time Performance
(4) In the case of a new flight, carriers shall assign a performance code consisting of the letter “N.” A flight that is not a new flight shall be assigned the performance code calculated for the flight that it replaces, even if the two flights do not have the same flight number. In the case of a flight scheduled to operate three times or less during a month, carriers shall assign a performance code consisting of the letter “U.”
(c) Carriers shall calculate on-time performance percentages and assign on-time performance codes on a monthly basis. This process shall be completed no later than the 15th day of each month, when the reports required by this part are due to the Department, and the codes shall reflect the previous month's operations.