What triggers the helicopter to search for the player(s) when scoping Cayo Perico?

As I was scoping Cayo Perico island for the ‘Gather Intel’ part of The Cayo Perico Heist (my third return to the island to scope for additional intel), I noticed in the minimap that a helicopter manned by the island’s guards has appeared and was shown to be looking for interlopers. Pavel then said something like "An aircraft has taken off from El Rubio’s compound, and now might be the best time to leave."

What causes the helicopter to spawn? Is it a time-based trigger or is it because of actions by the player(s)?