AT-400
The AT-400 is a large passenger plane in Grand Theft Auto: San Andreas, obtainable inside the large airport hangar in Las Venturas Airport in Las Venturas. Its large size and sluggish response makes it harder to land than the other planes in the game. Only the AT-400 and the Hydra can fly to the maximum height in the game. Like the other planes, it can also be seen flying in the distance, but it is hard to take down the flying AT400, even with homing rockets. One disadvantage to this plane is once you land and get out you can't get back in because the door is very high from the ground. The only way you can get back in it to find a Baggage with a ladder attached to the back, or land the plane at Las Venturas Airport and go to the hangar again. The AT-400 is based on the 737-400 Boeing_737-400.
Unlike most other planes, this plane is the only one that can be flown over Area 69 with less chance of being shot down by homing missiles, providing you don't hang around.
Trivia
The AT-400 is the biggest vehicle in the game, the next biggest is the Andromada. Interestingly enough, when comparing their real life counterparts the cargo plane (Andromada) is actually bigger than the passenger jet (AT-400).