From Singapore, must layover in Manila first, There are only 2 flights a day from Manila to Batanes,
Philippine airlines, or
Skyjet air.
Ideal time to visit there is January to May, summer season, the rest of the year will be rainy and typhoons.
You can inquire more from trip advisor, more experts there. Or read my travelogue :
http://saventravel.blogspot.sg/search/label/Batanes
Sharing more interesting sceneries..
Ever seen an unmanned coffee shop, pay your own, no cashier, no shopkeeper..
Stone house, typhoon proof -