The three people who died on a sightseeing tour of the Grand Canyon have been identified as a veterinary receptionist, her boyfriend and his brother.
Family and friends of 27-year-old Becky Dobson, 30-year-old Stuart Hill and 32-year-old Jason Hill say the Britons had gone to Las Vegas to celebrate Stuart Hill's birthday.
Dobson's father told Britain's Press Association news agency that they had been looking forward to the trip for a long time.
The three were killed when their helicopter crashed Saturday onto the jagged rocks of the Grand Canyon on the Hualapai reservation outside the boundaries of the national park.
Three other British tourists and the pilot survived and were airlifted to a Las Vegas hospital.
The National Transportation Safety Board and the Federal Aviation Administration are investigating.