Las Vegas ? A second wrongful death lawsuit was filed Thursday in a Nevada court against the Las Vegas-based operator of a sightseeing tour helicopter that crashed and killed five people earlier this month.

The lawsuit filed in Clark County District Court in Las Vegas seeks unspecified damages from Sundance Helicopters Inc. on behalf of four children of Delwin and Tamara Chapman, both 49, of Utica, Kan. The Chapmans were celebrating their 25th wedding anniversary when they died Dec. 7 in a remote ravine near Lake Mead.

“It’s horribly sad,” attorney Gary Robb of Kansas City, Mo., said of the effect the crash has had on the Chapman family.

Sundance offered condolences to the Chapman family but didn’t respond to allegations in the lawsuit.

“Sundance will continue to work openly with all parties involved in the investigation,” company chief executive Larry Pietropaulo said in a statement.

Robb filed a similar civil wrongful death lawsuit Dec. 13 in Las Vegas against Sundance on behalf of the families of Lovish Bhanot, 28, and Anupama Bhola, 26, a couple from India killed in the crash. That case is pending.

Robb said he plans to consolidate evidence collection for the two cases but seek separate trials.

The pilot, Landon Nield, 31, of Las Vegas, was also killed. Nield was a devout Mormon who grew up in Wyoming and Utah, and a newlywed. He was married in June.

Robb pointed to radar tracking data made public by the National Transportation Safety Board that showed the six-seat Aerospatiale AS350-B2 aircraft spun into what Robb called an “erratic and abnormal” flight pattern in the last minute before the crash. A final NTSB report on the cause of the crash and possible safety recommendations could take a year.

Robb said he suspected pilot error or mechanical failure.

NTSB officials said the ill-fated helicopter, built in 1989, underwent routine maintenance the day before the crash — including installation of a replacement engine and mechanical devices called servo-actuators in the tail and main rotor.

The aircraft made one test flight and two passenger tours before the fatal last flight. NTSB investigators found evidence the engine was producing power when the aircraft crashed.

Nield made no emergency call before the chopper went down, and a search and rescue team reached the charred scene and determined there were no survivors.

The wreckage was found in rugged terrain about four miles west of the Lake Mead reservoir behind Hoover Dam on the Colorado River.

The area remained closed Thursday to visitors pending completion of fuel and toxic material clean-up, wreckage removal and landscape restoration, said Andrew Munoz, National Park Service spokesman for the Lake Mead National Recreation Area.