(K, = 220) for 30 tower shots with } 2 100. The horizontal part of line A represents the mean K-factor (K, = 25) of 40 airbursts. There is a substantial difference between detonations on steel towers and those that are air burst. We consider a burst on a building to be comparable to a burst on a massive steel or concrete tower; similarly a treetop burst is comparable to an airburst. The most critical point for establishing the dependence of K-factor on building height appears to be the Trinity shot, analogous to one megaton on a 30-story building. If wooden towers can be considered analogous to treetop-burst conditions, several points in the two figures are analogous to treetop bursts. only well-established ones are those for Smallboy and the two Little Fellers. The For lower elevations we have Koon, whose suspension does not fit these categories, and Coulomb B, burst on a wooden tower but with a poorly documented fallout pattern. For air and treetop bursts, the Subcommittee recommends using line A in Figures 1 and 2, which amounts to a factor of about 0.45 for a scaled burst height, X}, of 10. This is uncertain to the extent represented by the spread in the Small Boy data. As for bursts on buildings, the available data indicate that line B should be used, which is to say a height-of-burst correction of only 0.87 at a scaled height of burst of } = 10. This effect cannot reduce the K-factor below about 220 no matter how tall the building. As in Chapter 1, DCPA needs a K-factor (K) that does not reflect reductions for instrument response or ground roughness. On this basis, the minimum K-factor (K,) for bursts on buildings is about 390,