Common threads run through many of the more than 100 crashes of medical evacuation helicopters that have occurred in the United States during the past decade.
Investigators from the National Transportation Safety Board say these common factors include:
* Pilot error, often influenced by darkness, bad weather or unfamiliar terrain.
In a South Carolina crash that killed three crew members and a patient last year, "Night visual meteorological conditions with mist and light fog prevailed in the area of the accident site," the NTSB said in its report on the accident.
* Inadequate flight planning, often the result of the emergency nature of many medevac flights.
In one fatal 2004 crash, NTSB investigators blamed the pilot's "inadequate planning/decision, which resulted in his failure to maintain terrain clearance. Contributing factors were the pilot's inadequate preflight planning, his diverted attention, and the dark night conditions."
* Failure to notice or anticipate obstacles, a particular problem for helicopters, which typically fly much lower than fixed-wing aircraft. The fact that many accidents occur at night adds an extra hazard.
In a Nevada crash that killed three crew members and an infant patient last year, the evacuation helicopter crashed while in cruise flight in mountainous terrain shortly after the moon set.
* Failure to recognize and successfully transition from visual flight rules to instrument rules.
In a Florida crash last year, the NTSB noted, "instrument meteorological conditions prevailed at the time and no flight plan was filed."
* The difficult terrain which many emergency landing sites are located.
In December of last year, a medevac copter crashed while attempting to land in a shopping center parking lot in Apache Junction, Ariz., killing one crew member. The pilot apparently lost control while trying to make a safe approach through a maze of overhead wires and other obstacles.
* Excessive focus on the mission.
In an accident near Pyote, Texas, last March, a pilot accepted a patient transfer mission knowing that "yellow" weather conditions, including thunderstorms and possible damaging hail, were expected. The fact that the patient was an infant might have influenced the pilot's decision to fly.
* Sometimes, even clear, calm weather can be deceptively dangerous.
In a 1995 crash near the Winslow ferry dock, the NTSB noted that calm, clear conditions prevailed and that the surface of the water was "glassy" and mirror smooth.
The "lack of visual cues" in such an environment may have confused the pilot and made him think he was at a higher altitude. Three crew members died in the ensuing crash.
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Jeff Standaert: 253-597-8354
jeff.standaert@thenewstribune.com
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SIDEBAR: Northwest Companies
Airlift Northwest
Founded: 1982
Base locations: Puyallup/South Hill, Seattle (home base), Arlington, Bellingham, Wenatchee, Juneau, and Ketchikan
Covers: Primarily Western Washington and Alaska
Aircraft: Four helicopters, four planes
Employees: About 160
Northwest MedStar
Founded: 1992, result of a merger between two air medical companies
Base locations: Spokane (home base), Moses Lake and the Tri-Cities. Moses Lake and Tri-Cities to merge next Tuesday.
Covers: Primarily Eastern Washington and parts of northeastern Oregon, northern Idaho, northwestern Montana and Canada
Aircraft: Five helicopters, two airplanes
Employees: About 100
Where are some helipads located around Tacoma?
* St. Joseph's Medical Center, Tacoma
* Tacoma General Hospital
* Clover Park Technical College, Lakewood
* Pierce County Airport - Thun Field, South Hill
* Auburn Municipal Airport
There are dozens of other landing zones that Airlift Northwest crews use in the area, including vacated school yards and empty parking lots, said Brenda Nelson, assistant chief flight nurse. Officials from local fire departments generally select these sites, she said.
The company requires landing areas that measure 60-by-60 feet to land during the day, and 100-by-100 feet at night, Nelson said. They can also land on closed highways or deserted country roads and logging areas, she said.
