MADISON, Wis. -- Twenty-three years of accident-free medical rescues by UW Med Flight ended in tragedy Saturday, with the fatal nighttime crash of an American Eurocopter EC 135 helicopter on a wooded bluff five miles outside downtown La Crosse (Wis.) on a return trip to Madison after ferrying a patient to a La Crosse hospital.
The craft lost contact with the airport shortly after take-off at 10:48 p.m. Killed in the crash were Dr. Darren Bean, nurse Mark Coyne and pilot Steve Lipperer.
The cause of the accident is under investigation by the National Transportation Safety Board, but several studies have found circumstances of such a flight -- at night and without a patient on board -- are linked with high accident rates in what authorities have identified as an alarming increase in the number of emergency medical services aircraft crashes.
In 2006, the NTSB threatened to tighten regulation of air ambulances, but opted instead for voluntary guidelines.
The NTSB had launched a special investigation into EMS operations and accidents after 55 air ambulances, helicopters and fixed-wing craft crashed between 2002 and 2005 -- a level not seen for 20 years, authorities said.
Recurring safety issues identified in the study included: less stringent requirements of EMS flights without patients on board; a lack of flight risk evaluation programs for EMS operations; and no requirements to use terrain awareness or night-vision technologies to enhance safety.
Other studies have pointed to factors that increase air ambulance crash rates.
A 2006 Johns Hopkins University study of NTSB data on EMS helicopter crashes between 1983 and 2005 found that the odds of a fatal outcome were increased by a post-crash fire, bad weather and darkness.
Post-crash fires resulted in fatalities in 76 percent of crashes, compared to 29 percent without fires. Weather conditions requiring instrument navigation resulted in fatalities in 77 percent of crashes, compared with 31 percent when pilots navigated visually. Fifty-six percent of crashes occurring in darkness were fatal, compared with 24 percent of crashes not in darkness.
There were no reports of a post-crash fire in Saturday's Med Flight crash, and the conditions were not considered risky at take-off, UW Hospital officials said.
The Air Medical Physician Association reported in 2002 that a study of 20 years of data showed that while 38 percent of all EMS helicopter flights occur at night, 49 percent of accidents occurred at night. One study cited by the AMPA identified peak accidents times, including 10-11 p.m.
The AMPA report also found that 60 percent of air ambulance crashes occur without a patient on board.
Med Flight operated a fleet of two EC 135s leased from Air Methods of Denver. The craft that went down was secured in August.
The Med Flight program averaged three to four flights a day, transporting patients an average of 55 miles, officials said. The program served a 225-mile radius.
The state's first EMS helicopter crash occurred in April 2006 when a craft operated by Eagle III crashed at a Green Bay emergency service heliport following a post-maintenance flight. The pilot was killed.