FAA Administrator Randy Babbitt was grilled by a House panel on Thursday over the agency's request for a 32% jump in funding for the NextGen air-traffic control system. Babbitt told lawmakers that NextGen is complex and interdependent, "not unlike a symphony," and that "some of the complexities have proven to be bigger obstacles than forecasted." But some committee members were concerned by delays in implementation as well as vague cost estimates for key components such as ADS-B. Babbitt declined to give a per-aircraft figure for ADS-B avionics, though he said the figure was relatively low. "Everybody equipped is everybody best served," he said. "If more aircraft are equipped, our entire system runs better."