Nuclear facilities such as nuclear power plants must be constructed safe for aircraft crashes pursuant to the valid safety regulations. Examinations have showed that the risk to the facilities depends on fast flying military aircraft. To ensure that the aircraft does not penetrate walls and ceilings, wall thicknesses of about 1.5 m reinforced concrete are required. The calculations are based on the crash of a Phantom RF-4E. It has been checked that this wall thickness is also sufficient for Jumbo jet crashes involving for example a Boeing 747 where even less thick walls would be sufficient due to the lower crash speed and the larger impact surface. The safety precautions also consider the consequences of an aircraft crash such as fuel fire and fuel explosion or missile effects.