It wasn't immediately clear what caused the crash, which occurred around 12:40 p.m. at Greenwood Lake Airport in West Milford.
The pilot sustained serious injuries and there is substantial damage to the aircraft.
Investigators say the pilot was the only person in the plane.
Federal Aviation Administration spokeswoman Holly Baker says police have responded to the scene in Passaic County.
The airplane is an Aero Vodochody L39C.
The plane is registered to Air Vatche Inc. from Wilmington, Delaware.
The Associated Press contributed to this report.