(1) The transportation revenue derived from transactions and activities in the regular course of the trade or business of the taxpayer and miscellaneous sales of merchandise, etc., are included in the denominator of the receipts factor as provided in ARM 42.26.253. The numerator of the receipts factor is the total revenue of the taxpayer in this state during the income year. The total revenue of the taxpayer in this state during the income year is the result of the following calculation:

(a) the ratio of departures of aircraft in this state weighted as to the cost and value of aircraft by type, as compared to total departures similarly weighted multiplied by the total transportation revenue. The product of this calculation is to be added to any nonflight revenues directly attributable to this state.