These early complexes while safe from a nearby nuclear detonation, however, had certain drawbacks. First, the missiles took about 15 minutes to fuel, and then, one at a time, had to be lifted to the surface on elevators for launching and guidance, which slowed their reaction time. Rapid launching was crucial to avoid possible destruction by incoming missiles. Even though Titan complexes were designed to withstand nearby nuclear blasts antenna and missile extended for launch and guidance were quite susceptible to even a relatively distant miss. The missiles sites of a squadron were placed at least 17 (usually 20 to 30) miles apart so that a single nuclear weapon could not take out two sites. The sites also had to be close enough that if a site's guidance system failed it could "handover" its missiles to another site of the squadron.