She is first heard in the level, "Charlie Don't Surf" while the Blackhawk Helicopter Sgt. Jackson is on is traveling to the coast. She is also seen in the level "Shock and Awe" where she covers Outlaw 2-5 and the ground forces advancing on the city. She is shot down by a Stinger missile right when the nuclear device is said to be probable by the NEST team. Vasquez volunteers to stay behind and help her out. This unfortunately seals the fate of everyone in Jackson's squad and Pelayo herself.
Vasquez leads Jackson and the other squad members out into the streets and Jackson helps Pelayo out of her helicopter. Her right leg is broken, and Jackson is forced to carry her. After helping her escape from the threats below, Khaled Al-Asad's nuke goes off, killing everyone on the helicopter and downing many other helicopters as well. When the player staggers out of the crashed helicopter, she can be seen on the ground next to the crash site.
Pelayo delivering MP5 fire out of the helicopter at an overwhelming enemy force is similar to a real life situation protrayed in Black Hawk Down, in which the pilot of the crashed Black Hawk shoots enemy insurgents with an MP5 as they try to overtake him and his rescue team.
There is a building named "Pelayo's" on the multiplayer map Favela and on the single player mission "The Hornet's Nest".