This is actually quite good advice. If you're close enough, you're dead regardless, but even miles away from an impact you still need to protect yourself against things like flying glass and falling debris.
Kind of like the Israeli standard warning to get into a concrete stairwell if you hear a missile alarm and don't have a real bomb shelter available. In a direct hit you're dead anyway, but mild defensive measures can vastly reduce the lethal radius of an attack.
Kind of like the Israeli standard warning to get into a concrete stairwell if you hear a missile alarm and don't have a real bomb shelter available. In a direct hit you're dead anyway, but mild defensive measures can vastly reduce the lethal radius of an attack.
EDIT: Here's a vintage poster on the subject. Fairly factually correct, but awful for morale: https://i.redd.it/fw2xx579qw401.jpg