A truck driver was on a hands-free call in cruise control and another was twice the drink-drive limit, when they were involved in a crash on the M1 that left eight people dead, Reading Crown Court has heard.
The crash happened on the southbound carriageway of the M1 near junction 14 at Newport Pagnell in the early hours of Saturday, August 26, 2017.
Ryszard Masierak, 32, and David Wagstaff, 54, face eight counts of causing death by dangerous driving.
They are also charged with four counts of causing serious injury by dangerous driving, and Masierak faces an additional charge of drink-driving.
Prosecutor Oliver Saxby told the court the crash was "entirely avoidable", reports the BBC.
Polish national Masierak had stopped in lane one at about 3am, despite there being miles of hard shoulder available.
Minibus driver Cyriac Joseph was waiting with his hazard lights on to go around the lorry when Wagstaff ploughed into the back of the van forcing it into and under Masierak's vehicle.
Joseph and seven of his passengers were killed in the crash on the Bank Holiday weekend.
CCTV footage of the minutes leading up to the collision and of the crash were shown to the jury.
Saxby said the "catastrophic and tragic" collision was "caused by the driving of these two defendants".
"In Mr Masierak's case, under the influence of alcohol, parking up in the slowlane of the M1, an act as flagrant as it was dangerous. And in Mr Wagstaff's case, on a hands-free call completely failing to notice what was ahead of him, inattention on a gross scale."
The court heard Wagstaff did not brake or decelerate before ploughing into the minibus.
Masierak, of Barnards Close in Evesham, Worcestershire, and Wagstaff, of Derwent Street in Stoke-on-Trent, both deny all charges against them.
The trial continues.