LYME, N.H. (AP) – Investigators checked the burned wreckage of a World War II training plane Thursday, trying to discover what caused it to crash, killing a father and his 10-year-old son from Connecticut.

The plane crashed in a cornfield soon after taking off Wednesday afternoon from a small airstrip, killing Neils Van Gemeren, 46, and his son, Willem Van Gemeren, 10, both of Canton, Conn.

Witnesses reporting hearing a popping sound, then silence from the engine just before the crash.

The victims were visiting Van Gemeren’s wife’s brother, Terry Smith, who owns the Lyme landing strip from which the plane took off, according to Van Gemeren’s brother, Marco, of Hanover.

“He was an experienced pilot,” said Marco Van Gemeren. “I don’t really know what happened. He was flying before he could drive.”

Van Gemeren said planes were a big hobby for his younger brother. “He was involved with a lot of vintage aircraft. He loved to fly.”

Van Gemeren held several licenses from the Federal Aviation Administration, including flight engineer, flight instructor, airline transport pilot for multi-engine planes and commercial pilot for single-engine land and sea planes.

The plane was a Conveyer, model BT-13A, which was used to train World War II pilots, said FAA spokeswoman Arlene Murray. It was registered to Lawrence R. Smith Jr. Trustees in Connecticut.

It crashed about 100 yards from Colby Bent’s home.

“There were two noises,” he told the Valley News. “One, then another one 10 seconds later. It was very obviously a malfunction.”

Other neighbors also reported hearing the plane in distress.

“The engine was going,” said Betty Labombard, “then it did this kind of pop, then it was quiet. It was like a backfire.”