Jet Alone is a bipedal robot developed by Japan Heavy Chemical Industries, designed to supplant the Evangelions. Unlike the Evangelions, which have a limited internal power supply and must rely on external power cables for extended operation, Jet Alone has an internal nuclear reactor (likely a pressurised water reactor) and can function for at least 150 consecutive days. Jet Alone also requires no pilot, and is controlled by an onboard computer. Radio commands can be issued from a ground station. Being a robot and not a living being, Jet Alone cannot generate an A.T. Field. Shiro Tokita pushes aside the issue, describing the creation of an (artificial) A.T. Field as "only a matter of time."
Jet Alone is seen in Episode 07, when it goes out of control during a demonstration. It is stopped after Misato Katsuragi climbs on-board with the help of Evangelion Unit-01 and attempts to delete its programming, but Jet Alone is saved from a immient nuclear meltdown at the last moment.Gendo Ikari states towards the end of Episode 07 that everything went according to plan, suggesting that Nerv was behind the incident.
Jet Alone was named after Jet Jaguar, Godzilla's robot sidekick from Godzilla vs. Megalon. 
Exactly why Nerv saw Jet Alone as a threat is not made clear. Gendo needed the Angels destroyed in order to carry out his version of Third Impact. It is likely he was concerned that vital funding would be diverted from his division to the Jet Alone program if the demonstration proved a success, or that Jet Alone would, at some point, be used against Nerv.
- From the Renewal liner notes: The name of JA comes from the robot, Jet Jaguar, which appeared in the special effects film Gozilla vs Megalon (1973). Jet Jaguar was a robot whose design was chosen from submissions from the public, and when it was initially announced, its name was Red Alone. Jet Alone is a name made by combining Red Alone and Jet Jaguar.