MILWAUKEE — No one was believed to have survived the crash of a small plane that was carrying a six-member organ transplant team and their cargo of donor organs, authorities said yesterday.The team's lifesaving mission — carrying unspecified organs from Milwaukee for transplant to a patient in Michigan — was cut short when the Cessna Citation went down Monday night in 57-degree water shortly after the pilot signalled an emergency.

The pilot had reported a problem with its trim runaway system, said John Brannen, senior air safety investigator with the National Transportation Safety Board. The system controls bank and pitch, but it wasn't clear what caused the problem.

"We will piece together what we can of the wreckage," Brannen said.

Investigators also planned to look at the aircraft's maintenance records within the next few days.

Only small parts of the plane had been found so far. Human remains have been found but hadn't been identified.

Milwaukee County Medical Examiner Jeffrey Jentzen said he likely would have to use dental records and DNA to identify the victims.

"A high-speed impact in water causes explosion-type injuries," he said.

Those on board were two surgeons and two donor specialists from the University of Michigan Health System and two pilots who regularly fly their transplant missions.

The patient who was to have received the transplant organs was in critical condition, the university said. Jay Campbell, executive director of the Wisconsin Donor Network, declined to say which hospital the team was working with, citing privacy regulations.

The president of the United Network for Organ Sharing, the national organisation that co-ordinates organ transplants, issued a statement calling the transplant team "unsung heroes" even as she said privacy rules prevented the group from sharing information about the flight and transplant.

"Every day, thousands of professionals do their very best to ensure that the donation and transplantation process is successful," Dr. Sue V. McDiarmid said. "Because of their routine success, the public may not understand the risks they sometimes must take in recovering and transporting organs. They are unsung heroes, willing to take these risks for the purpose of saving lives."

The university identified those aboard the plane as: Dr. Martinus "Martin" Spoor, a cardiac surgeon who had been on the faculty since 2003; Dr. David Ashburn, a physician-in-training in pediatric cardiothoracic surgery; Richard Chenault II, a transplant donation specialist with the university transplant programme; Richard Lapensee, a transplant donation specialist with the university transplant program; and pilots Dennis Hoyes and Bill Serra.

The plane took off from General Mitchell International Airport in Milwaukee and was headed for Willow Run airport near Detroit, a 42-minute flight, Federal Aviation Administration spokesman Tony Molinaro said.

Just minutes after takeoff, the pilot declared an emergency and requested a return to Mitchell, Molinaro said. But the plane dropped off radar screens just after the pilot made that request and the Coast Guard was contacted.

Light rain was falling at the airport with wind of 12 mph, gusting to 22 mph, according to J.J. Wood, a National Weather Service meteorologist.

The plane was leased by the University of Michigan Health System in Ann Arbor, according to the university. It's owned by Toy Air and based at Willow Run Airport in Ypsilanti, Michigan.

The flight crew worked for Marlin Air Inc. A woman who answered the phone at Marlin Air declined comment yesterday.

There were 55 accidents involving emergency medical services flights — those carrying patients or organs for transplant — between January 2002 and January 2005, according to the most recent National Transportation Safety Board study on the issue. The study found several safety problems, including less stringent requirements for EMS flights that did not carry patients.