Man relives horror of 'senseless' smash

Broken specs, an Armani purse, a wallet.

These few personal effects scattered across a southwest Sydney highway formed a grim inventory, cataloguing three lives lost: 59-year-old Calvyn Logan and his 81-year-old parents, Donald and Patricia.

"Nothing of any consequence - except perhaps for the ring that my father had put on my mother's finger just four months earlier, on their 60th wedding anniversary," Gary Logan told Sydney's District Court on Friday.

Mr Logan said the loss of his brother and his parents - killed when a drug-affected, sleep-deprived truck driver slammed his B-double into their sedan in January 2012 - haunted him.

The man responsible for the smash, Vincent Samuel George, was found guilty earlier this year of three counts of manslaughter.

Blood samples revealed the 34-year-old had methadone in his system when he veered onto the wrong side of the Hume Highway near Menangle, in Sydney's southwest, and crashed into the Logans' car.

"Death is inevitable in this world. But for my parents and brother to be killed so senselessly and so violently is too shocking, too reprehensible to contemplate," Mr Logan said.

"They did not deserve to die in such a horrific way."

The afternoon of January 24, 2012, should not have been remarkable.

Mr Logan's parents and brother were on their way home after a trip to Canberra to meet a loved one's newborn.

They'd planned to call in for lunch at Mr Logan's Campbelltown home.

But when they didn't show at midday, Mr Logan began sending a series of text messages that grew increasingly frantic.

At five o'clock, Mr Logan glanced at an online news story and saw a photograph of the carnage.

"I immediately recognised (my brother's) car. I scanned the story. Elderly woman deceased in the back of the car, two other bodies uncovered in the front," Mr Logan said.

"Location: about five minutes' drive from our front door."

What should have been a pleasant family day ended with a trip to the morgue on the other side of Sydney, and the loss of three people so well-loved that 1300 people turned out to their memorial service, either in person or via video-link from New York or Sri Lanka.

George sat with his head bowed in the dock as members of the Logan family held hands in the public gallery, entering the witness box himself only for a moment.

"If there was some way I could've went off that bridge myself, to save a family, I would have," he said.

"I never meant for anyone to get hurt."

Outside court, Mr Logan questioned George's remorse.

"Just to say it shouldn't have happened doesn't really mean a lot, does it," he said.

District Court Judge Stephen Hanley took aim at the driver's employers.

"It seems to me they must have known he wasn't compliant with his sleep requirements," he said, adding that George appeared to have made little attempt to hide his drug use.

"I just find it extraordinary that they either weren't aware of it, or if they were aware of it, they didn't do anything about it."

George will be sentenced on September 12.