Spirit Airlines, the Florida-based low-cost carrier, is adding 11 new routes this fall from Orlando to destinations in the Caribbean, Central America and South America in what the company says is one of its biggest growth spurts ever. The new routes include Aguadilla, Puerto Rico; Bogotá, Medellin and Cartagena, Colombia; Guatemala City; Panama City; Santa Domingo, Dominican Republic; San José, Costa Rica; San Pedro, Honduras; San Salvador, El Salvador; and St. Thomas, US Virgin Islands. Spirit already serves all these destinations from Fort Lauderdale, its busiest hub. Spirit operates a fleet of all Airbus aircraft, flying only narrow-body planes. It operates a single-cabin configuration but with between four and 10 “big front seats” on all aircraft with extra legroom.