Blackbird report is a holotape in Fallout 4.
At a random location (mailbox) Doctor Carrington has directed the Sole Survivor to during Butcher's Bill 2.
Railroad agent: Blackbird spotted. Badly injured. Way too many hostiles for the runner to engage. Request assistance from HQ.
The Railroad agent in this holotape was voiced by Brandon Keener, who also voiced Drummer Boy.