Generally. Except as set forth in paragraph (d) of this section, the standard industry fare level (“SIFL”) for coach/standard service in a market is equal to the predominant fare in effect in that market on July 1, 1977, as adjusted by the Board for cost increases.

Predominant fare. For each market, the predominant fare in effect on July 1, 1977, is presumed to be as set forth below. The presumption may be rebutted, however, by showing that more passengers used a higher fare.

For U.S. Mainland-Puerto Rico/Virgin Islands markets where the Board has specified day-of-week fare differentials: the peak-season midweek fare appearing in tariffs in effect on July 1, 1977.

For U.S. Mainland-Puerto Rico/Virgin Islands markets where the Board has specified only seasonal fare differentials: the off-peak-season fare appearing in tariffs in effect on July 1, 1977.

For U.S. Mainland-Hawaii markets: the peak-season second class fare appearing in tariffs in effect on July 1, 1977.

For all other interstate and overseas markets: the lowest unrestricted fare in effect on July 1, 1977.

Adjustments for cost increases. The Board adjusts the SIFL at least once every 6 months by the percentage change, since the previous adjustment, in the actual operating cost per available seat-mile for interstate and overseas transportation combined. The method of adjustment is illustrated in the example set out at the end of this subpart.

Intrastate markets in California, Florida, and Texas. For each of these markets, the SIFL is equal to the level that it would be if the market were an interstate one whose predominant fare on July 1, 1977, was the DPFI formula fare.

Intra-Hawaii markets. For intra-Hawaii markets, the Board's flexibility zones are based not on the SIFL, but on the standard Hawaiian fare level (“SHFL”), which is equal to 110 percent of the first class fare in effect on July 1, 1977, as adjusted by the Board for cost increases.