 Although "Ehime Maru" was at this point heading toward "Greeneville"'s location, Waddle failed to see the ship.Regulations mandated that Waddle conduct a three-minute, 360-degree periscope scan before executing the emergency main ballast blow maneuver.Waddle, however, aware that they were still behind schedule, conducted a short scan, searching primarily in the sector where he believed
the known contacts were located, noted that the haze was still present, and saw no ships in the vicinity.