In Avengers: Endgame after Thanos arrives and destroys the Avengers base, we see War Machine yell out, "Canopy! Canopy! Canopy!" This appears to be a command which releases him from his suit and allows him to move freely.
My question is what is the significance of the phrase? Why would that specifically be the command to set him free from the suit? Is it based on any real systems or was it a fabrication of the movie?
I realize that's three questions so to summarize, what I really want to know is the origin and significance (if any) of the command.