49 CFR § 91.11 - Standards.

(a) To minimize the burden of implementing this part on the United States, on U.S. flag air carriers and on foreign air carriers, estimates and periodic adjustments will be used to determine the amount of discrimination and compensatory charges therefor.

(b) For the purpose of determining the amount of excessive or otherwise discriminatory charges imposed upon U.S. flag air carriers by an entity:

(1) A service or use of airport or airway property includes, but is not limited to, fueling, food service, ticketing, baggage handling, runways, ramps, parking areas, navigational aids, communications facilities or any other service necessary and incidental to the conduct of a flight.

(2) An excessive or otherwise discriminatory charge includes, but is not limited to, a charge substantially above the cost of providing a service or any charge for a service that is substantially inferior to that which the U.S. flag air carrier could have provided for itself, at the same cost, by contract or otherwise (see also § 91.3).

(c) In determining the amount of compensatory charge:

(1) The total amount of excessive or otherwise discriminatory charges levied against U.S. flag air carriers will be estimated in dollars.

(2) The total volume of operations to the United States by air carriers of the nation concerned will be estimated for the succeeding six-month period.

(3) The total amount of excessive or otherwise discriminatory charges in paragraph (c)(1) of this section will be divided by the total volume of operations in paragraph (c)(2) of this section, and

(4) The quotient thus computed (which may be adjusted to reflect the type of aircraft) will constitute the compensatory charge to be collected as a condition to acceptance of the general declaration at the time of landing or takeoff of such air carriers of the nation concerned.