Reacción a "Reactions to the fall of a large Chinese rocket fragment to Earth have closed part of the airspace"

In a re-entry, we cannot predict precisely where the debris of the object will fall (if it reaches the surface of the Earth and does not burn up in the atmosphere, as in this case, because it is a large object). Because of the high speed at which it moves, it travels a long way in a short time and an error of a few seconds in the prediction of the time of entry means kilometres in the journey.  

Normally, we paint the areas where it may fall, such as all those through which the object flies within 20% of the time remaining until it enters the surface, around the predicted date of its entry. If there is one day left, we paint for about four hours, which is about two full circles of the Earth. That's why we see these traces in many places where there is a certain risk of it falling. 

It has finally fallen in the Pacific. We are lucky that most of the Earth's surface is water and not land, so the probability of it falling into an ocean is very high.