HARDING TOWNSHIP - Federal investigators are continuing to search for debris from the fiery plane crash in Morris County yesterday.

Two New York City investment bankers were among the five killed after the plane went down on Route 287 in Harding Township. Investment firm Greenhill & Co. says two of its managing directors were aboard, one with his wife and their two children.

The National Transportation Safety Board (NTSB) says the investigation into the cause of the crash could take up to a year. The NTSB says it's made a lot of progress and has recovered some large sections of the plane, including the cabin and part of a wing. It was announced that investigators now believe the pilot noticed ice beginning to form on the plane.

The Federal Aviation Administration says the plane departed from Teterboro Airport for DeKalb Peachtree Airport near Atlanta, Ga., when there was a garbled transmission and the aircraft disappeared from radar.

An audio recording of air traffic controllers talking to the pilot revealed they warned him about icing conditions up to 17,000 feet. Investigators say the plane had requested clearance to climb to 17,500 feet before it spun out of control and crashed.

It was also announced at a news conference today that the plane's maintenance records have been obtained and will be reviewed.Investigators: Too early to draw conclusions on ice in I-287 crash News conference on Morris County plane crash VIDEO: Plane crash path, debris litters area around Route 287 Many on the ground call themselves lucky following plane crash Witnesses recount Morris County plane crash