there was no such similar incident taking place
Well, not exactly that, but the first Antarctic expedition by Rear Admiral Richard Evelyn Byrd Jr. took place while the story was running in the papers, and I am sure that that, with planes landing on that continent for the first time, and - launched on November 28, 1929 - the first flight over the South Pole and back, must have put sorties speculating what the next record to fall might be in the public consciousness.
It's probably Hergé playing such achievements for laughs that he suggests that such a feat might be about to be performed by a diminutive Belgian, or that he might be mistaken for such a daredevil pilot; however, he and his young readers must have been enthused by the way in which aviation was coming along in leaps and bounds, and while it was obviously going to take time, it won't have seemed wildly outlandish to suggest that once the poles had fallen to pilots, that someone would take up the challenge of pole-to-pole flight.
As you say, it didn't actually happen for a long time, but hindsight is a marvelous thing; there were all sorts of stories about how man would develop permanent Moon-bases and take trips to both the Inner and Outer Planets when Neil Armstrong set foot on the Moon. Nobody at the time could say it would certainly happen, but then again, nobody would have thought that man would stop going to the Moon almost as soon as he'd got there either.