North Central flight 261, a CV-580, collided in mid-air with Cessna 150 N8742S (Home Airmotive) at 2700 feet. The Cessna cabin remained attached to the Convair’s forward baggage compartment. The Convair made a safe emergency landing at Milwaukee. The 3 Cessna occupants were killed. The Cessna was on a VFR flight from Lombard, IL to Sheboygan, WI. PROBABLE CAUSE: “The inability of the Convair 580 flight crew to detect the Cessna 150 visually in sufficient time to take evasive action, despite having been provided with three radar traffic advisories concerning the latter aircraft. Visual detection capabilities were substantially reduced by the heavy accumulation of insect smears on the forward windshield and direct vision windows of the Convair. Visibility was further reduced by haze, smoke and sunglare, and by the inconspicuous colour and lack of relative motion of the Cessna. Under these circumstances, the crew of the Convair should have requested a radar avoidance vector.”