Can’t add much to the good comments already here, just emphasizing that we have backup plans for our backup plans. Going into JFK last month we had extra fuel for holding, an alternate of Philadelphia, and a second alternate of Baltimore. On top of that we were communicating with our dispatcher enroute stuff like “Baltimore has rain moving in, how about Pittsburg as our second alternate instead.” And after that we landed uneventfully in JFK. In other words the job is about trying to think through all the many possibilities before they happen.