Brava has no working airport -- the old airstrip near Faja d’Agua is closed. The only way to reach the island is by ferry from Fogo, and getting here requires patience and flexibility.
The ferry schedule is erratic. Enquire locally and be prepared to wait a day or two for a crossing, especially on the return -- build spare days into your plans if you have a flight to catch from Sal or Praia. On a good day you will get the large ro-ro ferry that also connects with Praia. Otherwise it is the small boat, built for cargo rather than passengers, with room for about 30 people clinging to whatever they can find. The sea between Fogo and Brava is usually rough. You can stay on the open deck and get soaked, or go below and get seasick. The crossing takes about an hour.