The increasing cost of jet fuel is expected to lead to significantly higher airfares, driven by strong demand for travel as much as the cost of fuel. Despite higher ticket prices, airlines are booking record-breaking numbers and are likely to keep higher fares as long as passengers continue flying. United CEO Scott Kirby stated that the longer consumers pay these prices, the more likely it is to hold. American Airlines CEO Robert Isom said customers have already been willing to pay more for things like extra legroom or seats closer to the front. The price of fuel has doubled since the start of the year and is a major factor behind the widespread fare increases. Airlines are already charging passengers 20% more for every mile they fly compared to the previous year and are expected to increase further. There is also the possibility that Spirit Airlines, a trendsetter in ultra-low fares, could fold due to higher fuel costs.