During the early days of the Belkan War, Rainer and Orbert flew interception tasks in Belka's southern defense line, the "Hydrian Line". In these days, the Gelb Squadron effectively served as "errand boys" for the Belkan military, fly as much as five sorties in a single day's span without even basic maintenance. As time passed and the southern battlefield expanded, logistics took a major blow, becoming increasingly infrequent or even paralyzed in wide areas. Despite these unfavorable circumstances, Rainer and his flight lead managed to rack up considerable kill scores.
In May 13, 1995, Rainer and Orbert were returning from an intercept mission to Dionbill AFB, their home base, when they received an emergency transmission from Directus, the capital of the Republic of Ustio, which had been the target of a massive siege from the Allied forces. Upon arriving, they found that the city had already fallen, as bells tolled across the city to commemorate the event. Ready to make a last stand for the Belkan military, the Gelb Squadron clashed with the mercenaries of the 66th AFU Galm. At the end, the Galm Team proved victorious and the Belkan pilots fell. Orbert was killed, however, Altman managed to eject from his Terminator, descending with his parachute into Directus, being later saved by a local family.
After the war, he decided to stay in the city. During his military career, he was writing a novel, which was later released to critical acclaim. In September 2005, he was interviewed by Osean reporter Brett Thompson, as part of his documentary, Warriors and the Belkan War. Currently he continues living in Directus married and probably with children.
- In Mission 18 (Megalith) of Ace Combat 04, a friendly ground unit inside Megalith hollars "Altman! Use your hand grenades!" It is uncertain if this is the same Rainer Altman.
- During the interview escene introduction can be seen the detailed Rainer Altman identification card, his ID number was 903230, its date of issue was November 3, 1993 and the expiration data November 6, 1996.
- "Gelb" is German for "Yellow", given the fact that Gelb team flies the SU-37 Terminator, it's a safe guess that this is a direct reference to Yellow Squadron, from Ace Combat 04, who fly the same model aircraft.