How low-cost airlines alter the economics of flying

Low-cost carriers force the big airlines to figure out a way to draw the most price-sensitive fliers

For more than three years, the average one-way fare between Detroit and Philadelphia never dipped below $308, and sometimes moved higher, topping $385 at one point.

But then, early in 2016, fares suddenly started to fall, according to data from the Bureau of Transportation Statistics. By the end of the year, the average one-way ticket between the two cities stood at just $183.

What changed? The primary factor was Spirit Airlines.

The low-cost carrier began operating flights from Philadelphia International Airport to Detroit in April 2016, offering one-way fares for less than $100, in some cases. Spirit’s move into the route pushed down