The engineer in me is always pleased by a plane with extra bits added. This Learjet 60 was departing San Jose. As it taxied out, you could see a lot of extra probes on the front fuselage and some antennae on the fin. It is a Federal Aviation Administration jet, hence its abbreviated registration number. I assume it is used for flight checking services when the performance of things like instrument landing systems is calibrated. Whatever it does, it has a few added extras compared to the average bizjet.