Therefore, passengers can be relatively more sensitive
to the cost of the air travel price, even though it is only
one component within the overall cost of travel. Air travel
itself is a derived demand, based on the demand for
passengers to travel to another location for business or
leisure purposes. The other components of the journey
cost are derived from the decision to travel and are
essentially complementary goods to air travel (i.e. they
have a cross-price elasticity to air travel prices of less
than zero).