Three methods of assessing response of a building subjected to impact load due to collision of an airplane were investigated using simple models. Main method was to compute time history response subjected to impact load with triangular shape and duration which were based on findings obtained by the full-scale aircraft impact test. The other two methods were based on the conservation of momentum and transfer of energy using coefficient of restitution of 0. The main method can possibly evaluate impact response of building due to collision of airplane in the range of smaller τ/T.