Iwan was employeed by the KLM in 1921.
On 23 October 1925, he married to the Danish actress Margot Linnet. Three years later, he obtained the Dutch Nationality.
He was captain of the famous Christmas flight from 1933 to the Dutch East Indies.
In first instance this flight would be carried out with with the new Fokker f.XX PH-AIZ "zilvermeeuw". Due to engineproblems however this machine was unusable at the nigth of departure. The only machine that was available was the significantly slower Fokker f.XVIII PH-AIP "Pelican".
Albert Plesman decided that, Smirnoff, and its crew (first officer Piet Soer, Marconist C. H. Beukering and fligthengineer J. Grosfeld) had make the flight with this aircraft. The crew managed to fly to Batavia and back in a record time.
During the second world war, he managed flyingt for KLM as much as possible.
Initially, the line Naples-Dutch East Indies, later from Lydda to Dutch East Indies.
After Japan occupied Dutch East Indies, Smirnoff flew evacuation flights flew to Australia.
On 3th March 1942, he started with the Douglas DC-3 PK-AFV for the last evacuation flight from Bandung. Just off the coast of Australia he was attacked by three Japanese fighters.
Smirnoff made an emergengy landing on a beach, despite the fact that he was hit in his arms by four times. Before they were rescued, 4 passengers died because of their injuries.
During the rest of the war, Smirnoff flew for the Transport Command of the United States.He also tested possible KLM aircrafts, in order to make the right choices when the war would come to an end.
At the beginning of 1944, Iwan came back to Europe in order to fly the KLM England-Lissabon line. In 1946 he put on Dutch soil. In 1947 he stopped active flying and became KLM inspector,
His wife, Margot, died that year. 23 september 1948 Iwan remarried with Mina Redwood. Both marriages were are childless. In 1949 he retired and stayed at the island of Majorca till his dead in 1956