Small asteroids can impact Earth unexpectedly, as demonstrated by the Chelyabinsk event in 2013. The warning times are likely to be short, and the first tools for fast hazard predictions have been developed in the last years for encounters with rocky or cometary objects, which quickly fragment in the atmosphere and cause airbursts. However, in the projectile diameter range <20 m (and possibly up to 50 m), the ground effects caused by the entry of iron asteroids, denser and stronger than other objects, are much more severe than for rocky asteroids of equal energy. The existing prediction tools do not provide reliable results for such scenarios. In this work, we first review historical iron falls and related damage, and then discuss the applicability of existing semi-analytical models for iron falls. We compare the calculated damage caused by the Barringer crater formation with early estimates. Finally, we present our new model, which allows us to estimate the maximum damage envelope caused by iron meteoroids with unknown strength.
