Foxtrot Alpha Six

From The Stargate Omnipedia

Military alert code issued at the start of the Foxtrot Alpha Six simulation, warning Stargate Command personnel that an intruder has breached the iris and invaded the complex.

Because the training simulation is based around the threat, this alert code likely exists at the real Stargate Command.

KEY EPISODE

Avatar - Sergeant Harriman issues the Foxtrot Alpha Six alert at the beginning of each round of the virtual reality unit simulation.