graveyard spiral
n.— «He told naval authorities that while he was over Cherry Point in thick clouds at 40,000 feet the Banshee suddenly went out of control and nosed into a “graveyard spiral,” a downward banking motion at increasing speed.» —“’Chutes 6 Miles And Lives” by Lloyd Norman Chicago Daily Tribune Sept. 17, 1949. (source: Double-Tongued Dictionary)