LA CROSSE, Wis. -- A faulty altitude detector was cited as a contributing factor in the last fatal crash of the same kind of helicopter owned by the same company as the Med Flight chopper that crashed Saturday night near La Crosse, Wis.
The National Transportation Safety Board, which is investigating the UW Hospital Med Flight crash that killed three, said a faulty radar altimeter contributed to the crash of a Eurocopter EC135 helicopter in the Potomac River in Washington, D.C., in January 2005.
Pilot error was the main cause of that crash, and night conditions also contributed, the NTSB said.
That helicopter, like Med Flight's EC135 that crashed, was owned by Denver-based Air Methods. A radar altimeter measures the distance above ground, while a regular altimeter measures the distance above sea level.
Air Methods spokesman Craig Yale said Tuesday the helicopter it leased to Med Flight that crashed Saturday almost certainly had a working radar altimeter. Since the 2005 crash in Washington, which killed two people and injured one, the company has required that radar altimeters be operable for all night flights, Yale said.
"There's nothing to suggest there was any issue with the radar altimeter on this one," he said.
A preliminary report on the cause of Saturday's crash is expected next week, but a final determination could take up to six months, authorities said.
Mark Hanson, Med Flight program manager, said Tuesday that the air ambulance service will continue leasing its aircraft from Air Methods.
"There is no reason for us not to continue going with them," Hanson said.
Four other crashes involving EC135s, including one that was fatal, have occurred since 2003, according to the NTSB.
The Med Flight helicopter that crashed shortly after 10:30 p.m. Saturday -- along with Med Flight's remaining chopper and about 60 percent of Air Methods' national fleet of 330 aircraft -- wasn't equipped with two other pieces of equipment the NTSB has recommended: night-vision goggles and a terrain warning system.
Air Methods officials said they are in the process of upgrading all of their fleet with that equipment but must wait in line behind the military and other customers to buy it. Purchasing and installing both pieces costs about $100,000 for each helicopter, the officials said.
A terrain warning system alerts pilots to the ground before them, while a radar altimeter indicates how high they are above the land they just passed, Yale said.
The Med Flight helicopter apparently flew into a hill or hit some trees, officials have said. Killed were Dr. Darren Bean, 37, nurse Mark Coyne, 53, and pilot Steve Lipperer, 39.
Investigators removed the mangled aircraft Monday from the wooded crash site in the town of Medary. The wreckage was taken to the La Crosse airport for a detailed examination, said NTSB investigator Tim Sorensen.
"We'll be looking at the engine, control systems, all the systems on the helicopter," he said. "... We'll be looking at records, we'll be looking at weather ... everything that might have affected the operation of the flight."
Med Flight's other helicopter remained grounded Tuesday, and Hanson said regional hospitals are handling calls for service for now.
The La Crosse Tribune contributed to this report.