Anderson Dos Santos with his baby daughter, Maria, pictured soon before the fatal crash.

A momentary lapse in concentration by a Queenstown driver killed a man who had celebrated the birth of his daughter about six weeks earlier, the Queenstown District Court heard yesterday.

After pleading guilty to careless driving causing death, Brad James Nielson (31), sales representative, said the moment would "haunt" him for the rest of his life.

Nielson's appearance before Judge Dominic Flatley followed a fatal head-on collision between the Holden Viva he was driving and a Mazda Familia, driven by Anderson Luiz Dos Santos (32), an employee of Wakatipu Recycling, near the Shotover bridge, on State Highway 6, on January 8, 2010.

Nielson was ordered to pay $10,000 reparation to Mr Santos's family and disqualified from driving for nine months.

In his letter of apology he read to the court, Nielson said it was a terrible accident which had affected many lives, especially Mr Dos Santos' widow, Grace, and their now 10-month-old daughter, Maria.

Both had returned to Brazil.

Neilson said he had felt "scared, sad, could not sleep.

"Nightmares I could not answer ... If God allows me, I just want to stop my brain".

"This has had a profound effect on my life ...

"The pain I have experienced is nothing compared to the loss you have experienced and I am deeply sorry."

Counsel Phena Byrne said Neilson was not intoxicated at the time of the crash and there was no excessive speed.

It would never be known why Neilson had driven across the centre line.

He could not remember, possibly due to trauma.

Ms Byrne said Neilson was upset after reading Mrs Dos Santos' victim impact statement, which said Mr Santos planned to take over his retiring father's business in Brazil, but the family was now "struggling".

Neilson was still working light duties and had lost the second of two jobs he was working at the time.

He had not driven since the incident.

Taise Miranda, a friend of Mrs Dos Santos of 10 years, was in court, but declined to speak.

Kevin Neilson, the defendant's father, told the judge the family had met friends of the Dos Santos family to convey how sorry they all were.

It was "a tragic accident with the worst possible outcome," Kevin Neilson said.

Judge Flatley told Brad Neilson the crash was "a tragic accident and standing there as you are now would be anyone's worst nightmare."

The judge said it was not clear exactly why the defendant crossed the centre line twice.

"If you had been able to correct the vehicle the first time, you must have had some knowledge of why you were drifting.

"It may have been because you were tired."

The judge acknowledged Neilson was working two jobs at the time: "You were doing that to get ahead in life, but perhaps that was the cause of the accident ...

If that was the cause of the accident, you were careless, absolutely, but I don't know for sure what happened."

Judge Flatley said there were no aggravating factors, apart from the death, and Neilson did not have prior convictions.

Mitigating factors included the remorse he had clearly shown in reading his letter, the judge said.

"This will go with you for the rest of your life and that is a significant consequence.

"It's fair to say it could probably happen to any one of us."

However, the judge said drivers needed to take fatigue seriously and a message had to be sent.

He accepted the $10,000 reparation Neilson said he was able to pay by Friday.

Mr Dos Santos had lived in Queenstown since 2005.

An appeal was opened by colleagues and friends to help pay for his body to be returned to Brazil his home country for burial.