The soldier, a sergeant identified only as INQ 1832, kept the notes for 27 years before destroying them as he prepared to give evidence to the Bloody Sunday Inquiry.
In January 1972 he was personal assistant to General Sir Robert Ford, the Commander of Land Forces in charge of the Army's day-to-day operations, he told the inquiry sitting in central London.
Soon after British paratroopers shot dead 13 unarmed men on the Derry civil rights march in January 1972, Sergeant INQ 1832 left for a posting in Germany.
He had accompanied Gen Ford on the ground on Bloody Sunday and wrote up the general's diary of his movements that day.
In his inquiry statement Sergeant INQ 1832 said: "Even at that stage, I had a sixth sense that the events that day might come back to haunt me (although I was thinking in terms of months not 27 years)."
In the summer of 1972 Sergeant INQ 1832 made notes from these documents, destroying the originals. He disposed of these copies for fuller typed notes in 1998.
Michael Mansfield QC, representing some of the families of the bereaved and wounded, told him: "You had seen something terrible that day which you knew would come back to haunt you."
Records show Sergeant INQ 1832 was at an observation point on the Embassy Ballroom roof. From his vantage point Sergeant INQ 1832 had a good view of the Bogside overlooking most of Rossville Street up to the Rossville Flats where the incidents took place, the inquiry was told.
Mr Mansfield said: "What I want to ask you is whether the destruction of notes and the use of the word 'haunt' is because when you were on the roof, you did see effectively what was massacre and you have erased it?"
Sergeant INQ 1832 denied the allegation, saying he had badly used the word "haunt".
The hearing was adjourned until Monday.