The reasonable costs projected for a carrier providing essential air service at an eligible place will be evaluated:

For costs attributable to the carrier's flying operations (direct expenses), by comparing the projected costs submitted by the carrier with the following:

The carrier's historical direct operating costs with the same or similar aircraft types;

The direct operating unit costs of similar carriers using the same or similar equipment; and

Data supplied by the manufacturer of the carrier's aircraft.

For other costs, by one or more of the following methods:

By direct assignment where the indirect costs are attributable to the carrier's operations at the eligible place;

By comparing the carrier's systemwide indirect operating expenses to those submitted by the carrier for the eligible place; or

By comparing the indirect operating expenses submitted by the carrier with the ratio of indirect to direct costs that have been experienced by the carrier in other markets or to costs that are representative of the industry.

By considering the unique circumstances of the carrier or the community being served that justify deviations from the costs that would otherwise be established for that carrier under this paragraph.

By determining whether the aircraft to be used by the carrier at the eligible place, and on which its costs are derived, are appropriate for providing essential air service there. The appropriateness of the aircraft to be used is based on the following characteristics of the eligible place:

Traffic levels;

The level of air service that the Department has decided is essential for the eligible place;

Distance to the designated hub;

The altitude at which the carrier must fly to the designated hub; and

Other operational elements involved.

When the essential air service would be made part of the carrier's linear system, the Department might, instead of the factors in paragraph (a) of this section, consider only the incremental costs that the carrier will incur in adding that service to its system.