(Story updated at 3:15 p.m. ET.)
Investigators returned Wednesday to the scene of a medical helicopter crash that killed three people in West Tennessee
, but an official said the preliminary cause of the crash was not expected for more than a week.
Two hospital workers and a pilot died Tuesday when the helicopter crashed en route to pick up an ailing child in Bolivar.National Transportation Safety Board
spokesman Keith Holloway said investigator Ralph Hicks was working at site of the crash in a wooded area of Somerville, about 45 miles east of Memphis. Hicks is expected to give a briefing Wednesday afternoon, though a preliminary cause of the crash is not expected for roughly 10 days, Holloway said. A final report on the crash could take a year or more, Holloway said.
Meri Armour, president and CEO of Le Bonheur Children's Hospital, said the Hospital Wing helicopter was cleared for both weather and flight plans when it took off. Authorities began searching when the helicopter didn't respond during a routine 10-minute check-in.
Corey Chaskelson, a forecaster with the National Weather Service in Memphis, said there were clouds at about 4,000 to 5,000 feet, but "we do not know if weather was a factor."
In a news release, the hospital identified those killed as 47-year-old pilot Charles Smith, 43-year-old nurse Carrie Barlow and 43-year-old respiratory therapist Denise Adams.
Barlow worked as a nurse in West Tennessee for 13 years. She lived in Halls with her husband, Keith, and was the mother to three children.
Adams had served as the hospital's Pedi-Flite respiratory therapist for the past eight years. She lived in Arlington with her husband, Rodney, and was the mother to three children.
Smith began his career at Hospital Wing in 2012, the same year he retired from the aviation unit of the Memphis Police Department after 25 years of service. He lived with his wife, Chi, and their two sons in Eads.
The sick child was not aboard the aircraft and was eventually taken by ground ambulance to Le Bonheur, Armour said.
Hospital Wing is a nonprofit air medical transport partnership with Le Bonheur and other Memphis-area hospitals.
Another of its helicopters crashed in West Tennessee in March 2010, when the pilot tried to outrun a storm. That crash killed the pilot and two nurses.
At that time, improving the safety of emergency medical services flights was on the NTSB's "most wanted improvements" list.
It first made the list in 2008, a year when the industry suffered a record 28 fatalities in seven helicopter accidents. The agency's focus on the problem may have had some impact.
According to statistics provided by NTSB, 2011 and 2012 each saw only one fatal helicopter emergency medical services crash. But those numbers began to creep up again this year. Including Tuesday's accident, 2013 has seen five fatal helicopter EMS crashes with 12 killed.