It appears to be an industry-wide problem. Continental's RASM for March was down about 20%...makes 12% look kinda rosy by comparison.

http://online.wsj.com/article/BT-CO-...01-717103.html

In this case, jetBlue is probably helped by not having a first- or business-class cabin. I think there are fewer business customers willing or able to pay premium fares.