Story highlights The 10,000-ton USS Fitzgerald and the ACX Crystal collided early Saturday

Japanese coast guard revises its crash time estimate to 1:30 a.m.

Washington (CNN) Nearly an hour passed before the crew of a container ship reported its collision with a US destroyer, according to the Japanese coast guard, raising more questions about the sequence of events that ultimately led to the death of seven American sailors.

The 10,000-ton USS Fitzgerald and the ACX Crystal, a 29,000-ton container ship flagged in the Philippines, collided early Saturday local time off Japan's Izu Peninsula, officials said. The area sees heavy maritime traffic, with 400 to 500 vessels crossing it daily.

Initially, the Japanese Coast Guard said that the distress call from the ACX Crystal came at 2:25 a.m. on Saturday -- five minutes after it crashed into the USS Fitzgerald at 2:20 a.m.

But after interviewing the ACX Crystal's crew, the Japanese coast guard revised its crash time estimate to 1:30 a.m.

Japanese officials say a delay of 50 minutes or more between when the collision occurred and when it was reported would not be unusual for the merchant ship, as the crew could be busy determining damage to the vessel and avoiding other craft in the busy shipping lanes.

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