Flights are absolutely a spreader event. No question about it.

But good luck tracing it or proving it. The people on flights are from a variety of physical places and have a variety of destinations. With cases being tracked by county and people on flights from many counties, these counties are not sharing data that says Sick1 from Red County, Sick2 from Blue County, and Sick 3 from Orange County were all on Air Flight 666 so Air Flight 666 was a spreader event. They also were all just in the airport terminal (so prove the flight was the spreader event, and not the airplane terminal waiting area), many just in a rental car or other shuttle, or just used other public transportation the same day.

As far as the employee without a mask covering the nose, who knows if there was a reason. Medical reason or something. I see that all the time out in retail stores people wearing masks like that while doing physical work.