Section 399.36 - Unreasonable discrimination(a) As used in this section:(1)Unreasonable discrimination means unjust discrimination or unreasonable preference or prejudice; and(2)Rate means rate, fare, or charge.(b) Except in unusual circumstances or as provided in paragraph (c) of this section, the Departmentwill find a rate for domestic air transportation to constitute unreasonable discrimination only if: (1) There is a reasonable probability that the rate will result in significant long-run economic injury to passengers or shippers;(2) The rate is in fact discriminatory according to a reasonable cost allocation or other rational basis;(3) The rate does not provide transportation or other statutorily recognized benefits that justify the discrimination; and(4) Actual and potential competitive forces cannot reliably be expected to eliminate the undesirable effects of the discrimination within a reasonable period.(c) A rate that discriminates on the basis of the status of the traffic carried will not be presumed to be unreasonably discriminatory, unless the use of the status categories in question is contrary to established national anti-discrimination policy.PS-93, 45 FR 36062, May 29, 1980