The world's most punctual airports and airlines for 2019 revealed
https://edition.cnn.com/travel/article/most-punctual-airlines-and-airports-2019/index.html
We should take it for granted that airplanes are to be delayed by 1 hour. By doing so, we won't be worried about departure time of connecting flights or schedules after arriving at your destinations.
If your flight is delayed by more than 1 hour, you have to take it as an unfortunate rare case.
