Feds can't find cause of plane crash that killed developer, colleague

BUTTE, Mont. -- Federal investigators say they can't determine the specific cause of a 2007 Montana plane crash that killed two men with ties to the suburbs, but icing on the aircraft could have played a role.

Allan Hamilton, 69, was flying his Cessna Citation 550 from Rockford on May 3, 2007, when he crashed while trying to land at the Dillon airport during a storm. Also killed was Hamilton's business associate, John "Mark" Wauterlek, 30.

National Transportation Safety Board investigator Howard Plagens said in his report on the crash that the accident was caused by "an in-flight loss of control for undetermined reasons."

He said the potential for icing existed above 4,000 feet in elevation. Hamilton approached the airport at about 13,000 feet before beginning his final descent.

The airplane dropped 1,600 feet in 10 seconds, and a witness at the airport reported hearing a "loud engine noise" followed by a plop and then intermittent loud and softer engine noises.

Another witness saw the airplane below the base of heavy clouds turning hard to its right at a downward pitch of 75 or 80 degrees, according to the report. The witness said the aircraft made six or seven increasingly tighter turns before it disappeared from view.

Plagens determined the airplane was well maintained and in good working order. He said anti-ice fluid was found on the leading edges of the wings and tail.

Hamilton was a self-made millionaire who founded Hamilton Partners, known for such projects as Greenspoint office complex in Hoffman Estates.