Eye-witnesses, Frank Crawford and his wife, Kay, were the first to alert emergency services when they arrived at the pier to find a auto four or five inches in the water.
Those who died along with Mr McGrotty, from Londonderry in Northern Ireland, were his sons Mark, 11 and eight-year-old Evan, his mother-in-law Ruth Daniels, 57, and her 14-year-old Jodie-Lee Tracey.
Former footballer Davitt Walsh swam out and managed to rescue Mr McGrotty's four-month-old daughter Rionaghac-Ann.
Mr McGrotty passed his infant daughter out of the window of the Audi Q7 moments before it sank.
Louise James pictured with her Solicitor, Robert Anderson after The Buncrana Pier Tragedy Inquest at THe Lake of Shadows Hotel, Buncrana, Co.
John O'Raw said: "I am personally aware probably of three incidents over a 17-year career".
A local man named Davitt Walsh swam out to the family's sinking auto when he noticed the vehicle, saving McGrotty's young daughter.
Garda Inspector David Murphy said that the impact of the events of 20 March, 2016 have been felt in Derry but also in Buncrana, Donegal, across the country and even further afield.
He paid tribute to rescuers who arrived within minutes.
Coroner Dr Denis McCauley said the jury had handed the Irish safety authority a "golden key" in its dealings with other agencies, to become the main agency in raising prevention issues.More news: Pakistan court orders release of Hafiz Saeed
"It is a bad thing, we can see that it is just unimaginable".
"They did it with enormous thought for the tragedy that did unfold".
Mr O'Raw said that he tried the handles of the doors and they gave freely but the doors would not open.
Discussion also surrounded the use of laminated glass which made it considerably more hard to break through the windows, technical experts said. I tried to pull him out but he seemed to get stuck on something.
He added: "We truly hope the conclusion of the inquest will go some way to aiding the grieving process".
"Generations of a family have lost their lives, as we have heard in the course of this inquest".
Mr Callaghan, who is attached to Buncrana Garda Station, said he was at the scene with a colleague within a minute of getting the call at 7.15pm.
Following the inquest, Mr McGrotty's partner and mother to his children said she was still angry there were no warning signs and that a gate to the slipway had been left open.
She said that withstanding the evidence given in relation to her partner, he was a loving and kind man.
Mark McGrotty (12) was moved out of the vehicle through the tailgate, a police diver told the inquest.