Minutes before the attack, he phoned her from the cockpit to say: 'Are you home? I am just going to drop by!'
Then Konrad Schmidt, 47, banked the twin-engined aircraft over his mother's home and flew past it three times before flying at top speed into the house in Oberhallau.
Schmidt's body was later found in the rubble of the house. His mother Rosemary, 68, only survived because she was in the basement at the time of the suicide attack, and is being treated for shock.
Eyewitnesses told police there was 'no possibility' of an accident.
One told a Swiss newspaper: 'He had all these flypasts. He was lining himself up. And then he did it. It was like seeing a mini re-run of 9/11.'
Neighbours helped rescue Rosemary from the burning shell of her house, which will now have to be demolished. She told police of the air-to-ground phone call from the aircraft shortly before the attack yesterday.
Her son had rented the aircraft earlier in the day from an airfield 45 minutes away.
Jobless Schmidt had a long-running feud with his mother, according to neighbours. One told a newspaper, 'They had a lot of heavy issues over a lot of things.'
Media reports said Schmidt's father Otto was a senior pilot with national carrier Swissair, and was rarely at home during his son's childhood.
Konrad was brought up almost single-handed by his mother, and after his parents' marriage crumbled he was left bitter and disillusioned. He blamed Rosemary for the split, while his father moved out and died from cancer shortly afterwards.
Over the past two years, Konrad Schmidt had suffered depression and financial problems.