He was on vacation somewhere that day. I remember because some now-banned twit even posted a comment about "See, these things always happen when Rush is out of town!" Oy.
Anyway, WABC's antenna was on top of Tower One, so nobody was broadcasting anything from that station at noon. I don't remember how long it took them to get back on the air, because I wasn't paying much attention to the radio that week.
Some may hate this but Howard Stern was on the air when it happened and apparently his coverage was excellent that morning.