consideration may expect in the years 1956-1959 (see App D of this report). These times are based on the expected completion dates of the McGill, Pinetree, and distant-early-warn- ing (DEW) networks and the seaward extensions; flying speeds of enemy aircraft are assumed to be 550 mph by 1959. These figures are not firm but serve to indicate that targets face varying warning conditions depending on their location. The possibility of complete surprise, for coastal cities at least, may always remain high. TABLE 4 WARNING TiME OF BoMBER ATTACK ; City 1956 Warning time, hr 1957 | 1958 | | | 1959 Boston 0.5 0.5 1.0 1.0 St. Louis 2.0 25 25-40 2.5-4.0 Washington, D.C. Dayton San Francisco Milwaukee 0.5 1.5-2.0 0.5 1020 0.5 2.02.5 0.5 202.5 1.0 2.04.0 1.0 2540 1.0 2.54.0 1.0 2.54.0 In order to compare the effects of alternative civil defense actions, this study has assumed a massed attack by bomber-type aircraft. However, it should be pointed out that attack from ballistic missiles launched from submarines affords no warning before thefirst missile, and little warning before any remaining missiles. The maximum warning time from attack by IcBMs has been estimated at 15 min. It should also be pointed out that the time span of the attack has importantcivil defense implications; depending on the success of the initial attack and other factors, urban popu- lations could be subjected to subsequent attacks from ballistic missiles or aircraft over weet it me ge ee 3 periods of days or weeks. Somecivil defense actions may leave them more vulnerable to follow-up attacks than others. 20 ORO-—R-17 (App B) | ! | ;