A 2013 review of the radio transcripts and other data by astronomer and retired United States Air Force pilot James McGaha and author Joe Nickell proposes that the inexperienced Valentich was deceived by the illusion of a tilted horizon for which he attempted to compensate and inadvertently put his aircraft into a downward, so-called "graveyard spiral" which he initially mistook for simple orbiting of the aircraft. According to the authors, the G-forces of a tightening spiral would decrease fuel flow, resulting in the "rough idling" reported by Valentich. McGaha and Nickell also propose that the apparently stationary, overhead lights that Valentich reported were probably the planets Venus, Mars and Mercury, along with the bright star Antares, which would have behaved in a way consistent with Valentich's description.