An airplane in a flat spin has very high angle of attack. Way above
any normal spin mode. Once stabilized flat you are sort of like a
frisbee, rotating with all the incoming air hitting just the bottom of
the plane. The break out of this spin or any for that matter, you must
lower your angle of attack somehow. In upright spins this means, stick
full forward. Flat spins, fwd stick doesn't help because the air flow
is under not over your vertical control surface, stabilator in the F-4
case. The rotation can't be altered for the same basic reason. Power
changes don't give you any significant nose up or down impulse. If you
deploy your drag chute it will just ride above you and not inflate,
like a streamer. You have lots of time to try lots of things on the
way down but like I said, we lost a lot of F-4s trying everything but
never found anything that worked. Answer was, be gentle when using
rudders when vertical and nose high. The F-4 gave you plenty of
warning when you did something it didn't like. Wing wobble, some
buffet, very loose nose in yaw, and often some "Oh ****s" from the rear
seat. My theory, and I never tried it, was if all else failed in a
flat spin, have the back seater eject and maybe the reaction to the
seat firing would lower the nose a hair. You just never told the RIO
what your plan was. In Navy planes, he could eject me but I couldn't
eject him. A serious design fault IMHO. Actually there was a way to
eject the rear seat from the front but it wasn't widely advertised.