Reisen Travel offers helicopter service from suburban towns to John F. Kennedy International Airport.?

How would you determine the most important cost driver when estimating cost functions in the case of Reisen Travel? Identify the cost driver and how it would impact Reisen’s operating budget.

I am thinking the purchase of the helicopter would be the most important because without the helicopter they wouldn't be doing any kind of business. What do you think?

Fuel and pilots' wages. The helicopter can be leased.