Grand Theft Auto San Andreas The Definitive Edition
Mission: Black Project
Carl arrives at the airfield and is welcomed by The Truth, exercising on the top of an aircraft wreck. Truth then berates Carl for having agreed to work for a government agent. He then tells Carl about a secret military research area, where he believes a "black project" is being developed. Truth drops Carl off at the boundaries of the base before leaving the area.
Carl must sneak into the underground area, by using the control tower to open the blast doors and get inside. However, the area is well protected with several soldiers patrolling the area, as well as spotlights. If Carl is spotted by a spotlight, the blast doors will be isolated from the main system, which forces Carl to use a vent to get inside.
Once inside, the alarm goes off, and Carl is forced to kill every soldier on his way to the project. Upon arriving in a lab, a scientist gives Carl his keycard, which he uses to gain access to the launch bay, where the project, which turns out to be a Jetpack, is lying at the bottom. Carl steals it and flies towards Arco del Oeste, where Truth is waiting in his van. Truth takes it, then leaves the area, while Carl complains about Truth refusing to drive him back to the airfield.
Source: https://gta.fandom.com/wiki/Black_Pro...