Assessing the risk and the uncertainty affecting the uncontrolled re-entry of manmade space objects

In view of the statistical distribution of the predictions, an uncertainty window able to guarantee a confidence level of 90% should generally adopt an amplitude of about ±20% around the estimated nominal re-entry time, to be raised to about ±25% in the couple of days ahead of re-entry. An uncertainty window amplitude of ±30% would be, instead, needed to achieve a confidence level ≥95%.