GOLDMAN, Mo. (AP) - The plane carrying Missouri Gov. Mel Carnahan, his son and a campaign aide plunged about 3,200 feet in nine seconds before disappearing from radar, investigators said Wednesday.
Minutes earlier, Carnahan's son, who piloting the twin-engine Cessna, told air traffic controllers his artificial horizon, an instrument used to maintain level flight, was not working properly.
Carnahan, 66, died when the plane crashed Monday night in a hilly, wooded area about 25 miles south of St. Louis. Also killed were Roger Carnahan, 44, and Chris Sifford, 37, Carnahan's chief aide in his bid for the U.S. Senate.
National Transportation Safety Board member Carol Carmody said radar records show Carnahan's plane descending from 7,100 to 3,900 feet in nine seconds. NTSB investigators have ruled out an in-flight breakup of the plane, she said.
Carmody said that Cessna issued a service bulletin Oct. 2 on a part of the plane called a ''vacuum system manifold check valve.'' If the valve wasn't working, it could have affected the operation of the artificial horizon, she said.
''We don't know if this has any significance, but it is one of those things we will take a look at,'' Carmody said.
Weather data also showed shear winds at about 7,000 feet near the time of the crash, she said. A shear layer results when air masses collide and cause buffeting currents.
''This would be of interest to someone flying an airplane,'' Carmody said. ''I would think it might result in some turbulence.''
Earlier in the day, Carmody provided details of communications between Roger Carnahan and the control tower at Lambert Airport in St. Louis. Full transcripts were not released.
The Cessna 335 took off just before 7 p.m. from Parks Airport in Cahokia, Ill., near St. Louis. It was heading south, where Carnahan was to appear at a fund-raiser in New Madrid in Missouri's Bootheel.
At 7:20 p.m., Roger Carnahan said he was having trouble with the artificial horizon, which is used to judge whether the plane is tilting. Two minutes later, he sought permission to turn to the west toward an airport in Jefferson City.
Six minutes later, at 7:28 p.m., Roger Carnahan told controllers he was still having trouble and was trying to switch to visual flight rules, which means he was trying to find a path clear enough to fly by sight.
Air traffic control told him ''to just keep heading west'' to avoid fog and rain. The pilot said he was heading west, and then the tower lost radar contact with the plane at 7:33.
NTSB investigators have found a football-sized piece of the plane's engine more than a quarter-mile away from most of the plane's wreckage, something agency spokeswoman Carol Carmody called unusual.
The investigation could take months.
The aircraft had a clean track record, as did Roger Carnahan, an amateur pilot with more than 1,600 hours of flying experience.
Earlier Wednesday, Lt. Gov. Roger Wilson officially took over leadership of the state after a medical examiner identified the remains of Mel Carnahan and Sifford.
Wilson, like Carnahan, is a Democrat. He was sworn in as Missouri's 52nd governor at a brief ceremony after midnight attended by his family, Carnahan's staff and state lawmakers. He will serve out the rest of Carnahan's term, which ends Jan. 8.
''The people of Missouri have my pledge that I will do everything I can ... to make Missouri as productive as possible and a great place to live,'' said Wilson, who became lieutenant governor in 1992 and was re-elected in 1996.
Mel Carnahan had been battling Republican Sen. John Ashcroft in one of the nation's tightest Senate races. Carnahan's name will stay on the Nov. 7 ballot because the deadline to change it has passed. If Carnahan receives the most votes, Wilson can appoint a replacement to serve until the next general election, in November 2002.
Carnahan's casket will lie in state at the Governor's Mansion on Thursday for public visitation. President Clinton is expected to attend a memorial service Friday outside the Capitol in Jefferson City.
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On the Net:
State government: http://www.gov.state.mo.us
National Governors' Association: http://www.nga.org/subtocnga.htm
Campaigns: http://www.johnashcroft.com and http://www.carnahan2000.com