About an hour and a half after the plane took off, Robert had died.
Mr Rippingale said his family had been looking forward to his and his wife's combined 50th birthday parties last week when police officers told them Robert had died on the flight.
"They didn't take it very well, as you can imagine. It was a huge shock," Mr Rippingale said.
Instead of a having a birthday party on Saturday the couple buried their eldest son.
Mr Rippingale said he had really been looking forward to seeing Robert again and getting friends and family together for their birthday celebrations.
Tomorrow Mr Rippingale and his other son will fly to Singapore with Miss Preechakul to get Robert's affairs in order.
Robert Rippingale moved to Singapore, where he met Miss Preechakul, three and a half years ago to work at a perishable goods shipping company.