Considered we are in Brazil to get to Cumbuco is quite easy.
Fortaleza has an international airport, the Pinto Martins, served from Europe by scheduled flights (TAP from Lisbon/IBERIA from Madrid) and charter flights (from Italy with Air Italy and Livingston, from Holland with Arkefly, from Germany with Condor, and also from Sweden, Hungry, Finland, Switzerland and Poland).
In USA, Delta Air Lines flies from Atlanta to Fortaleza.
From the airport to get to Cumbuco takes about 45 minutes by car. It´s just 35 km northwest of Fortaleza.