PiperPower,
The ejection altitudes are based on the altitude required to recover the aircraft after you have recovered from a spin/departure (hope that makes sense).
So, if you are in a fully developed spin and you pass 6,000 AGL, you will NOT be able to recover the jet prior to hitting the ground even if you get out of the spin (according to the engineers).
Additionally, when you recover, you tend to be nose low (extremely low) and accelerating, and pulling high G's to recover. Ejecting now might be out of the envelope (or cause serious injury).
So for us it was a rule of thumb... if you're in a spin, and haven't started a recovery by 6,000 ft AGL, the plane is going to hit the dirt. Whether you are in the jet or not is your choice.
I don't think anyone would fault you if you pushed that 6K altitude a bit in order to save the jet but I know more than a few guys who waited too long before they pulled the handle and they aren't around anymore.
Most guys will do everything in their power to save the jet. Just like General Aviation we have procedures and memory items to go through. We practice CRM with our wingman and base as time allows. You do everything you can to save the jet and follow procedures but sometime the jet is just broken or won't fly anymore. Most jets have the glide characteristics of a coke machine. If you find yourself sitting in a coke machine at 1,000 ft you probably don't want to be in it when it lands.
Fighters have problems all the time and most land uneventfully. In some rare events the problems are so severe the only option to survive is to grab the handle.
When it's time to go, it's time to go.
Cheers,
ImTumbleweed
"Afterburner is a great substitute for poor headwork"