Fifteen months after a Bayflite medical helicopter hit a radio tower, killing its crew, federal investigators have reached a simple, unsatisfying conclusion about what had caused the crash:
The pilot made a mistake.
The National Transportation Safety Board released a final report Wednesday, blaming Bayflite pilot Mark Wallace for the April 25, 2000, accident. But it's clear now that some questions about the crash will never be answered.
Wallace, 39, was a seasoned helicopter pilot regarded by colleagues as safety-conscious and precise. That day, he was flying a route he knew well. He knew the location of that particular radio tower near Weedon Island.
After an exhaustive 15-month investigation, no one knows why Wallace flew into it.
"It's very frustrating. A very well-trained individual made some sort of mistake, and we don't know why,," said Karl Poulsen, director of operations for Rocky Mountain Helicopters, which leases the copters used by Bayflite.
The twin-engine BK117 helicopter had just dropped off a patient at Bayfront Medical Center in St. Petersburg and was returning to its base at St. Joseph's Hospital in Tampa. It was flying at midday in clear, sunny weather at an altitude of about 500 feet when it flew directly into a 649-foot radio tower.
The crash instantly killed Wallace, who was a husband and father of three; flight nurse Alicia Betita-Collins, 51; and paramedic Erik Hangartner, 29.
In blaming pilot error, the NTSB ruled out other possible causes such as weather or mechanical problems with the helicopter. Also, toxicology tests on Wallace found no trace of carbon monoxide, drugs or alcohol in the pilot's system.
Only a few days before the accident, Bayfront Medical Center had asked Bayflite to shift its standard route to Tampa slightly to the west because Snell Isle residents had complained about helicopter noise.
In the NTSB report, federal investigators repeatedly noted that Wallace "was flying a newly established route."
However, Wallace's employers downplayed the significance of the change in routes.
"It was not a new route. It was a slight variation, a version of a route that has been flown for years," Poulsen said. The NTSB noted that Wallace had flown in the area for 15 years and was familiar with local obstacles such as the radio tower, built in 1977.
Also, Bayflite pilots are not given specific routes. Those are left to pilot discretion, based on factors such as weather, air traffic and patient condition.
On Wallace's final flight, he got clearance to proceed from Albert Whitted Municipal Airport and then flew northeast toward Weedon Island, an area dotted with radio and television transmission towers.
The standard flight path would have taken the copter into a right turn and then on a course parallel to the Gandy Bridge. But that day, Wallace flew north of the usual point of the turn and hit the tower.
At normal flight speeds of 140-150 mph, Wallace would have had little time to avoid the collision. After that, Bayflite pilots began flying at higher altitudes, well clear of obstructions.