By mid-1971, the Royal Laotian Air Force had thirteen AC-47 "Spooky" gunships on strength and were conducting approximately 50 missions per month in support of government ground units as well as the Hmong tribesmen in the highlands. Though superstitious, the Laotion gunship crews readily adopted the Spooky call sign but would not operate the AC-47s seven crew members as Buddhist tradition regarded the number seven as an unlucky number. As a result, RLAF AC-47s went into combat either with one man short (six crew) or one man extra (eight).
Source: Gunships: The Story of Spooky, Shadow, Stinger and Spectre by Wayne Mutza. Specialty Press, 2009, p183.