Recovery efforts are continuing today for the wreckage of a 1981 Cessna Citation II that crashed into Lake Michigan soon after takeoff from Milwaukee late yesterday afternoon, killing all six aboard. The dead included two doctors and two specialists from the University of Michigan Health System, who were in Milwaukee harvesting human lungs for transplant. The Citation 550 (N550BP, S/N 0246) was owned by Toy Air of Southfield, Mich., and operated by Marlin Air at Willow Run Airport in Ypsilanti for the University of Michigan’s Survival Flight air ambulance service. Marlin’s chief pilot, Bill Serra, and copilot Dennis Hoyes were also killed. The aircraft departed Milwaukee for Willow Run at 3:59 p.m. At 4:03 p.m. one of the pilots declared an emergency and indicated they were returning to the airport. The aircraft then vanished from radar. Eyewitnesses reported seeing the Citation proceeding southbound en route to the airport along the lakeshore at a high bank angle before it rolled inverted and plunged nose-down into the water. Weather conditions at the time of the crash were reported as light rain with wind gusting from 12 to 22 mph. This is the third Citation 550 crash in a month, two of them fatal.