"Your son is gone but I'm still here," Hans told his 71-year-old grandfather Jijar Singh.
"I'm your son now and I will be the man of the house," the child was quoted as saying by Star newspaper.
Recounting his telephone conversation with the boy, Jijar said his grandson consoled him.
Jijar couldn't come to terms with his fate.
"We don't mind if one of us has to go first, but definitely not our son. This is not how the world is supposed to be," he said. "The older ones should depart first."
Jijar hoped Sanjid's body would be found and returned to his family so that final rites could be conducted.
Sanjid, 41, worked in the hotel industry for seven years before joining Malaysia Airlines on June 17, 1997.
His wife Tan Bee Geok, 43, also a MAS stewardess, heard the tragic news from her in-laws.
Sanjid's mother Jajit Kaur Sandhu, 73, said she called her daughter-in-law an hour after hearing about the tragedy from her daughter.
"She (Tan) said Bobby (Sanjid's nickname) was touching down at 6.10am," said Jajit.
"It was then that I realised she did know what had happened," said a teary-eyed Jajit at her home in Taman Selamat Alma in Penang.
"So, I told her that Bobby was no longer with us," the paper quoted the mother as saying.
The Boeing 777 was on a scheduled flight from Amsterdam to Kuala Lumpur when it was shot down over pro-Russia rebels-held territory of the eastern Ukraine on Thursday.
It is still not clear if the Malaysia Airlines Flight MH17 was shot down purposely or mistakenly.
All 298 people on board were killed in the crash.