LAS VEGAS (AP) — Federal investigators are looking at unexpected turns and a sudden climb that a Las Vegas sightseeing helicopter made moments before a crash that killed the pilot and four passengers who were marking marriage milestones.

A preliminary National Transportation Safety Board report issued Tuesday recounts details already made public by a board member who viewed the charred wreckage following the Dec. 7 crash near Lake Mead east of Las Vegas.

Radar records show that about a minute before the crash, the helicopter climbed 600 feet and turned sharply left, then fell 800 feet, turned left again and plunged into a ravine.

The report makes no conclusions or recommendations. Officials say a final report could take a year.

The NTSB has said the Sundance Helicopters aircraft had engine work the day before.

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