A minute later, the Spirit jet received an automated TCAS warning that required him to begin an immediate 1,600-foot descent to 12,800 feet from a previous altitude of 14,400 feet."
Wouldn't it be safer to go over and behind it?
I'm not sure why you'd want to dive
under a skydiving plane at that altitude. Jump planes typically want to dump their load at 12,500 feet
above ground level so the jumpers get around 60 seconds of free fall before deploying their chute.
Hence 12,800 feet may be close to their high altitude. At 14,400 feet or more, you should wear an oxygen mask in most jump planes, which is a bother.
Diving under them that high means you may miss the jump plane, but you could have parachutes sucked into your engines.