Heartbreak One is a mission in Ace Combat 5: The Unsung War.
In December 21 of 2010, the OFS Andromeda intercepts an encrypted transmission from Jack Bartlett, the former flight lead of the Razgriz Air Command Squadron. The message within, "18007130", is revealed to be a time and radio frequency. The crew of the OFS Kestrel gather at the carrier's bridge at the appointed time, at which point the lead speaker plays a message from Bartlett, in which he says that he, with the aid of the local resistance movement, broke Prime Minister Seryozha Viktorovich Nikanor out of prison.
Early the next day, Razgriz launches from the Kestrel and heads to Pobeda Peninsula, arriving at 07:00AM. Hidden in a bush, Heartbreak One contacts the team, and requests them to assist them as they make their way to their target, Krylo Airfield. The squadron receives an in-flight briefing, where they are indicated to escort Bartlett and arrive to the target before 07:05hrs.
Bartlett's convoy begins their journey towards the airfield, with Razgriz following them. The team protects the convoy from an initial onslaught of Yuktobanian aircraft, and the resistance vehicles reach a fork in the road. Under Blaze's guidance, the convoy will either take the long route or a shortcut, encountering several checkpoints and Yuke forces in their way to the target.
As the convoy approaches Krylo Airfield, resistance members inside begin their operations and seize an aircraft hangar, securing a C-1 Trader and moving it outside. With the aid of his former students, Bartlett and the resistance convoy eventually arrives to Krylo Airfield, bypassing the entrance and driving towards the hangar while dodging infantry fire. Bartlett and his entourage board the C-1 and take off.
Shortly after the Trader reaches the sky, Archer detects a formation of four F-15S/MTDs, belonging to the 229th Tactical Fighter Squadron "Grabacr", known also as the "8492nd Squadron". Razgriz and Grabacr engage each other in a short skirmish, which concludes with the defeat of the 8492nd. Following the interception, Heartbreak One and Razgriz leave east for the ocean to meet up with the Kestrel.
- YA-10B "Distant Thunder": Spawns in the vicinity of the Shtil prison after Bartlett escapes and the Grabacr encounter is initiated. Unlocks SP color for the YA-10B.
- In a rare occurrence, the C-1 used by Bartlett to escape is called by name by a Yuktobanian soldier on the ground.