Victims’ families flew in from across the country on Wednesday for a private memorial service at DAR Constitution Hall. That was a key factor in the crash, along with air traffic overly relying on asking helicopter pilots to avoid aircraft. The National Transportation Safety Board held a hearing on the probable cause of the tragic midair crash over the Potomac River a year ago this week. Reporting live on NBC Washington, anchor Eun Yang said she kept the victims’ families in mind. Almost immediately after the crash, aviation officials began making airspace changes aimed at making it safer to fly near D.C.