Landing at Quito’s Mariscal Sucre airport can be a white-knuckle affair. High altitude, a cramped runway and towering volcanos nearby make it one of Latin America’s most challenging airports for pilots. That all changes Tuesday as Quito opens a new airport in an agricultural area 12 miles northeast of the city. Of course, Mariscal Sucre sat amid cornfields when it was christened in 1960. Over the years, Quito grew dense around it, turning the airfield into a notoriously nerve-racking neighbor. The new airfield encompasses nearly 6 square miles, 12 times the area of the old airport, most of which will become a public park.