Jean Robinson died instantly after Fode Sidibe lost control of his car and and struck the pensioner as she waited at a bus stop stop with her friend.
A court heard takeaway restaurant worker Sidibe, 22, of Woodlands Village, Sandal, Wakefield, admitted to police he had been tired after he only got three hours sleep before the incident on July 9 last year.
Leeds Crown Court heard widow Mrs Robinson had been out with her friend Dorothy Mylroie to celebrate her ninetieth birthday.
The pair had been to Victoria Garden Centre, near Featherstone, for tea and cake and were waiting at a bus stop on Wakefield Road when the incident happened around 4.10pm.
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Dave Mackay, prosecuting, said a motorist driving behind Sidibe’s Vauxhall Corsa did not initially have any concerns about the defendant’s driving.
Sidibe drifted across the road to overtake a car which was turning into the garden centre, but he failed to return to his lane and continued across the carriageway.
Sidibe’s vehicle struck the kerb before mounting the pavement and hitting the two women.
Mrs Robinson was thrown into the air and struck and lamp post. The prosecutor said she suffered head, leg, rib and spinal injuries and would have died almost instantly.
Mrs Mylroie suffered serious injuries and was taken by helicopter to Leeds General Infirmary.
The court heard Mrs Mylroie can no longer walk more than a few yards due to her injuries.
Sidibe was in tears when police arrived at the scene. He told officers: “I can’t believe this has happened to me. I was tired. I know I should have stopped.”
Sidibe said he had been working at a takeaway until 4.30am that morning and had not gone to bed until 7am. He said he awoke around 10am and went to visit a friend in Pontefract. He was on his way home when the collision occurred.
Sidibe pleaded guilty to causing death by dangerous driving and causing serious injury by dangerous driving.
He was jailed for 32 months and banned from driving for eight years.
Mrs Robinson’s daughter described in a victim statement how her mother was a “much loved” charity fundraiser in the Barracks community of Pontefract, where she lived.
Richard Canning, mitigating, said Sidibe had pleaded guilty to the offences at an early stage and had no other convictions.
Mr Canning said Sidibe moved to the UK from Portugal when he was 15 and had a partner and six-month-old child.
Sidibe had passed his driving test six months before the tragedy.
Mr Canning told judge Robin Mairs: “He knows he should not have been driving because he was tired. It was dangerous.
“His remorse will never heal. He has been affected by this in ways your honour will not expect.”
Judge Mairs said: “You accepted that you had driven and you were tired.”
He added: “Jean Robinson was cherished by and cherished her family. She was active and generous in her community, well though of and regarded by all who knew her.”
A West Yorkshire Police spokesman said: “Sidibe drove his vehicle on little sleep and his exhaustion and dangerous actions caused the death of an elderly lady, and serious injury to another, who is understandably still devastated by what happened on that Saturday afternoon.
“Driving whilst tired is incredibly dangerous, not only to the driver and passengers within the vehicle but also to other road users.
“I hope that today’s sentence not only brings some comfort and closure to those directly affected, but also serves as a stark warning to motorists that getting behind the wheel when tired can have deadly consequences.”