Ottavio Missoni Jr. says it is "impossible" that no one would have seen his father's plane crash.
Italian fashion designer Vittorio Missoni, his partner Maurizia Castiglioni, two friends and two crew members are missing after their plane went off the radar off the coast of Venezuela on January 4.
The group were on a short flight from the Los Roques resort to Caracas when they disappeared and there has been speculation they might have been kidnapped.
The flight route is notoriously dangerous, with a plane carrying 18 people vanishing doing the same journey on January 4 2008. A life jacket which had been on board was discovered, but no other wreckage or bodies have ever been found.
Ottavio Jr. remains adamant his father is still alive.
"Searches cannot stop. I am also glad that this has re-opened the 2008 case. That can't be forgotten," he told Italian newspaper La Provincia di Lecco.
"We not only hope that my father Vittorio, his partner Maurizia and their friends are found but also the Italian tourists who disappeared in the same way years ago. With all the aircrafts that fly in that area no one has seen them falling? It’s impossible. I’m still waiting them to come back home.
"I still believe that they’re alive, that the plane didn’t fall: there is too much evidence that lets me think like this."
Ottavio Jr. was in regular contact with his father before the accident and there were reports he also received a text from the designer's phone after he had disappeared.
He has thanked the public for their "many positive messages" over the last few days, saying they have helped him stay strong.
Earlier this week, 28-year-old Ottavio spoke of his belief that the plane did not crash.
"I have been thinking of so many possible scenarios," he said. "But I remain convinced that the least plausible reason is that they crashed into the water. My uncle Luca, in Venezuela, has also confirmed that these planes are capable of sea landings in case of emergency."© Cover Media