K-503 fired two volleys of SS-N-9 missiles at the convoy. Unfortunately for NATO, the missile's initial altitude of Low was just outside their detection range. The missiles then go to VLow and cannot be picked up until they are 24 nm from Iroquois. I am using 30 second turns until they are detected.
EDIT: The detection range for the small missiles at VLow altitude would be 10% of the listed range for an Air Search radar (using smarter radars rule). So, the range to detect the vampires is actually 14 nm.