The airplane that took off Tuesday was climbing above Marine One as the helicopter approached, so the two aircraft were not on a collision course. “The air traffic controller was in contact with both the commercial pilot and Marine One pilot during the loss of separation,” the FAA said. The air traffic controller didn’t acknowledge that transmission and after the pilot tried again, the controller said the message was broken and unreadable. So when Marine One’s pilot announced the helicopter was proceeding as briefed, the controller seemed surprised. The rules also require air traffic controllers to use radar — and not rely on pilots’ eyes — to maintain separation and require all military aircraft to broadcast their locations.