[Secret History] (/s "At the book's end Briggs talks about setting up the "mayday protocols" at the LPA. He plans to bring Cooper in on the project, and meets with him almost immediately after the S2 finale:
12:05 PM MARCH 28, 1989
He just left. Something’s wrong. The message holds the answer, just as I thought, but I’ve misinterpreted it. Protocols are in place. I must act quickly.
I’m heading to the LPA alone.
[S3E4] (/s "Bobby mentions Cooper being the last person to see the Major alive, and that "the day after he died in the fire at his station." This makes it seem like Briggs died in the fire at the LPA days after the end of S2.
However, back in S3E2 we saw EvilCoop take a call from someone he believes is Jeffries. This person tells him "You met with Major Garland Briggs" as if this was a recent event. Considering the military-classified fingerprints on the headless body, the floating head of Briggs in the void, it seems likely that part of the Mayday Protocols may have been starting the fire himself and faking his death, that he tried to track EvilCoop, and was only recently killed for real...")