The widow of US basketball legend Kobe Bryant is suing the owner of the helicopter that crashed last month, killing her husband and 13-year-old daughter, Gianna.
Bryant, Gianna and seven others died when the helicopter they were in crashed in fog on 26 January.
In the lawsuit, Vanessa Bryant says the pilot was negligent for flying in such poor weather.
It was filed shortly before a memorial service held in Los Angeles.
Island Express Helicopters and the pilot, Ara George Zobayan, had a "duty to use that degree of care that an ordinarily careful and prudent pilot would use under the same or similar circumstances," the suit says.
It alleges that Zobayan - who died in the crash - did not assess weather data before taking off.
The suit says the pilot did not abort the flight despite the treacherous conditions.
The company authorised the flight "with full knowledge that the subject helicopter was flying into unsafe weather conditions", the complaint says.
Ms Bryant is seeking undisclosed compensatory and punitive damages.
Island Express Helicopters has suspended operations.
Bryant and Gianna were remembered in a "Celebration of Life" memorial at the Staples Center in Los Angeles on Monday.
Beyoncé opened the service with her 2013 hit XO, which she said was one of Bryant's favourite songs.
Basketball stars Michael Jordan, Magic Johnson and Bryant's former teammate Shaquille O'Neal were among those attending.
The Staples Center was Bryant's home arena for much of his 20-season career with the Los Angeles Lakers.
Speaking at the event, Ms Bryant said of her husband: "He was mine. He was my everything," and called her daughter Gianna an "amazingly sweet and gentle soul" whose smile took up her entire face.
What do we know about the crash?
Island Express Helicopters was limited to operating when the pilot was able to see clearly while flying.
The aircraft - a Sikorsky S-76B - went down into a hillside outside the city of Calabasas.
Conditions were foggy when the flight took off, and local police had grounded their helicopters due to the poor weather.
The pilot asked air traffic controllers for a special clearance, known as Special Visual Flight Rules, to fly in less than optimal weather, said NTSB board member Jennifer Homendy, who went to the crash scene to collect evidence.
The helicopter, she added, circled in the air for 12 minutes before being given the clearance. The pilot then asked controllers for "flight following", an assistance given to helicopters to avoid collisions, but was told the craft was too low to be picked up by radar.
Minutes later, the pilot said he was "climbing to avoid a cloud layer", she added. The helicopter climbed and began a left descending turn, according to radar data, before communication was lost. All those on board were killed.