A man walking his dog along the Potomac River in Northern Virginia on Sunday found what appears to be an airplane seat and a tray table among other airplane debris. The National Transportation Safety Board is now examining the debris, which is believed to be from the mid-air collision between an American Airlines regional jet and an Army Black Hawk helicopter near Reagan National Airport in January that killed 67 people. Andrew Guevara, who lives near the trail along the Potomac River, said he spotted the airline seat cushion while walking his dog.