NTSB investigators are still on scene examining the wreckage of an air tour helicopter for clues to what caused last week's deadly crash, hoping divers can find key pieces of evidence that may answer why the chopper crashed into the river killing all 6 aboard.

The National Transportation Safety Board said on Saturday that the helicopter involved in a crash that killed six people in New York earlier this week was not equipped with any flight recorders and that the accident occurred during the aircraft's eighth flight of the day.