Mark,
Would need a little bit more of his info before starting to find out what he is refering to. Eng. Hill was located north of Holloway and I don't remember anything which happened during that time frame that would have caused two ships to be shot down.
The area around Pleiku was not a place where air crews really felt any danger. Once you were outside that area things changed but Pleiku proper I thougfht to be pretty safe.