Yes I do know by experience that it is very easy to deduce if a flight will be delayed. By experience in Europe, last leg of the day of an Easyjet flight -> 75% chance that your flight will be delayed. Snow during the night (look at the forecast) -> 90% your morning flight will be delayed etc. etc. No need for an advance ML model. Of course what she did was more like insider trading, but I'm pretty sure that you don't even need that.