Machinbird,
From the Harvard Medical School, paper on "the physiological reactions to stress" date not known.
"This combination of reactions to stress is also known as the "fight-or-flight" response because it evolved as a survival mechanism, enabling people and other mammals to react quickly to life-threatening situations. (The carefully orchestrated yet near-instantaneous sequence of hormonal changes and physiological responses helps someone to fight the threat off or flee to safety.) Unfortunately, the body can also overreact to stressors that are not life-threatening, such as traffic jams, work pressure, and family difficulties."
So my point is that fight or flight is a response triggering what I include in parenthesis, above.
Stimulus. A-4? "Conflict in flight path, bad, dangerous, or Jesus!!" A response, dependent on the stimulus, and the physiology of the result, the "conflict" I don't mean to parse words, but to say Flee or Fight is spontaneous ignores the physiology the body describes.