"No close contacts," Tarkowski called out, slowing his periscope search to find more distant contacts or aircraft.

Decks awash," Turner announced, returning to a slow periscope search, the water's surface slowly climbing higher in the television monitor's view.

Pacino did a rapid low-power periscope search, scanning the horizon for approaching contacts or aircraft, then checked the supertanker-pier one last time.

Waddle later explained how he conducted his periscope search:

During Waddle's periscope search, Seacrest was busy operating other control room instruments and did not actively monitor his fire control displays.

The Greeneville hurried through crucial maneuvers - including a periscope search - in order to return to Pearl Harbor on schedule, he said.

Once a 180-degree periscope search confirms the area is clear, the submarine rises, usually within minutes, after sounding an internal alarm.

A standard periscope search, he testified, would last at least three minutes.

Another factor that has not yet been fully explained has to do with the periscope search itself.

It was also steaming south nearly head on, minimizing its profile in any periscope search.