The couple owned units at the Le Chateau Royale condominium in South Palm Beach and in the Golden Lakes retirement community west of Lake Worth. They were seasonal residents for several decades.
Their son, John B. Bialek, told the Chicago Tribune that his father was undergoing treatment for a blood infection and the couple had decided to return to Chicago to be near their children and grandchildren.
The plane was owned by Trans North Aviation, a firm that provides medical airlift service, and left West Palm Beach at about 6 p.m.
It refueled in Jesup, Ga., before beginning the final leg of the trip to Chicago Executive Airport in the suburb of Wheeling.
The pilot reported fuel problems and the plane went down about five miles short of the airport in a wooded area, barely missing a home, in Riverwoods, a northwest suburb, a Federal Aviation Administration official said.