The Egg Jet has a peculiar design, whose components are all blocky. Mostly colored grey with hints of red and black, it has a streamlined main body and attachments on the top and bottom reminiscing space shuttle fins. The rear and the recess in it is covered with five rocket exhausts.
The Egg Jet was used when Dr. Robotnik escaped from Wing Fortress Zone to the Death Egg, after he failed to get rid of Sonic in the Wing Fortress' cockpit room. While Sonic missed the Egg Jet, Tails returned with an enhanced Tornado and they chase after it. After a while, Sonic managed to grab onto the Egg Jet's side and rode it to the Death Egg where it docked. The Egg Jet is not seen since then and was possibly destroyed when the Death Egg crashed on Angel Island or when the Death Egg was completely blown up.
The Egg Jet's name was not mentioned in the games. Instead, it was mentioned as the name for its counterpart in the Sonic comics published by Archie Comics.
Eggman is known to have more space shuttles inside of his hidden pyramid base during the events of Sonic Adventure 2, as Sonic, Tails, Knuckles and Amy used one to get to the Space Colony ARK and then possibly used it to get back to the earth at the end of the game. This space shuttle apparently bears a heavy resemblance to the American space shuttle "Discovery," which was part of NASA's Space Shuttle program.
Eggman launching the Egg Jet from Wing Fortress Zone.
Sonic and Tails chasing the Egg Jet.
The Egg Jet docking at the Death Egg while Sonic is hanging on it.