The issue focused on when it was safe to board the aircraft that crashed at London's Heathrow Airport.As with any plane crash, there are always questions about what happened to the plane and what caused it to crash.But there are also questions about how it happened.What happened to the plane?On Friday the flight data recorder  from the crashed Airbus A320-200 came off the aircraft and was later recovered in the Western Isles.It was taken to the crash site at Scapa Flow in the Western Isles