As the administrator for Hadley's Hope, Simpson was in charged of the colony's day-to-day management. At some point in 2179 he received a message from Carter Burke to investigate a previously unexplored set of coordinates on LV-426's surface. Simpson passed this order on to prospectors Russ and Anne Jorden, who set out to investigate. The Jordens later contacted Simpson through the staff in the colony's operations center, seeking clarification on their rights to anything that they found, given that they were dispatched on specific Weyland-Yutani orders. Simpson was unable to provide them with a definite answer, but voiced his own opinion that, as far as he was concerned, anything that they discovered was theirs to salvage.
What the Jordens discovered was the Derelict Ship, triggering a Xenomorph outbreak on the moon that eventually overran the colony. Simpson and all but one of the rest of the colony's inhabitants perished in the resultant Xenomorph infestation.
- Al Simpson was cut from the theatrical release of Aliens when the studio complained that the film was too long. The scenes featuring him were later reinstated for the extended Special Edition.
- The scene featuring Simpson and Lydecker is almost identical to a scene in James Cameron's later film Terminator 2: Judgement Day: an employee flags down a supervisor in a busy office and they walk together, discussing the behavior of their employer — Weyland-Yutani in Aliens, CyberDyne Systems in Terminator 2 — before the more senior man ends their conversation with a line about their employer always responding to sensitive questions with the phrase "don't ask".