wow, such an aggressive response. I have no idea where or why you are using the numbers that you are, 24 hours? 20k feet? what happened to at altitude? I read it a couple of times...I have no idea what you are talking about, sorry.
I think he's referring to - if they make it to altitude - they don't need to be there for the full 18 months to understand whether or not it will acheive 18 months, give or take.