Air friction goes up with velocity squared, so a small decrease in speed gives you a relatively large savings in fuel. It's just too expensive to fly fast. Th

Air friction goes up with velocity squared, so a small decrease in speed gives you a relatively large savings in fuel. It's just too expensive to fly fast. There's a sweet spot where fuel savings, customer satisfaction, and capital costs meet, and it's at a much lower speed than engineers are capable of producing.