© Tim Boyle / GettyA 47-year-old man in northern Switzerland flew a small plane into his estranged mother's house, trying to kill her. His mother was in the basement and survived the attack.

Swiss authorities are investigating what drove a suicidal maniac to try to kill his mother by flying a rented twin-engine plane into her house.

Konrad Schmidt, 47, launched the kamikaze attack on his estranged mother's home in the northern Swiss village of Oberhallau on Saturday, authorities said.

The psycho pilot, who friends say was battling depression, died in the fiery crash.

He allegedly called his mom from the cockpit moments before the wreck.

"Are you home mum? I'm just about to drop in," Schmidt said, according to cops.

Seconds later, the unhinged fly boy crashed the plane through her bedroom window, killing himself, crushing the two-story brick home and igniting a giant fireball, Switzerland's Blick newspaper reported.

Rosemary Schmidt survived the attack because she was in the basement. She was treated for shock at a local hospital, and her house would have to be demolished, officials said.

Neighbors said they were terrified when Schmidt flew past their homes several times before he struck.

"He did all these fly-pasts. He was lining himself up to crash the plane into the house," one neighbor told Blick. "And then he did it."

Investigators said Schmidt had a long-running feud with his mother after she split with his father, a senior pilot with airline Swissair who was rarely at home.

His father died of cancer soon after the break-up, a police spokesman said.

"Schmidt felt very bitter and blamed his mother. He had also suffered depression and financial problems over the past few years," the spokesman told the newspaper.

Schmidt was an experienced pilot who rented the Diamond Aircraft DA42 from a local airfield earlier in the day.

Cops ruled out the chance that the crash was an accident.