Major carriers for CLT to BCN itineraries in May include American Airlines (often connecting via JFK or PHL), Delta Air Lines (via JFK or ATL), United Airlines (via EWR/IAD), and Iberia (typically via Madrid MAD with codeshares). American often offers convenient connections and Admirals Club access, Iberia may provide shorter European connections through Madrid but could require separate long-haul booking, Delta emphasizes comfort and SkyTeam connections, and United connects reliably via New Jersey or Washington hubs. Compare total travel time, baggage allowances, seat selection fees, and loyalty program benefits. Book flights with these primary keywords in mind to filter options: CLT to BCN flights, cheapest Charlotte to Barcelona flights, and best airlines CLT BCN in May.