Originally Posted by rbinhood
I am surprised that only one person warned you about going from your altitude to a much higher altitude at Vail. Altitude sickness can come on in a matter of hours and totally incapacitate you in a short time. If you get the cerebral edema form, it can cause unconsciousness in a few hours, and eventually death.
You can acclimate yourself easily by spending one night at moderate to high elevation (8000'). Car camp at the trailhead. If you have a headache in the morning, you may have mountain sickness, but it's not likely. This is how I prepared to climb Whitney, and I started getting mountain sickness only abot 12,000'. As soon as we hit the summit I rested and the headaches went away, especially when we started descending.