A jet carrying 60 passengers and four crew members collided Wednesday with an Army helicopter while landing at Ronald Reagan National Airport near Washington, prompting a large search-and-rescue operation in the nearby Potomac River. Less than 30 seconds before the crash, an air traffic controller asks the helicopter if it has the arriving plane in sight: “PAT-25, do you have the CRJ in sight?” The controller makes another radio call to PAT25 moments later: “PAT-25 pass behind the CRJ.”