A couple years back, a stowaway reportedly survived in the wheel well of a 767, LAX to Hawaii, with few adverse effects (~5-6 hour flight).
I was skeptical of the report but I don't think there was ever a retraction - something like he snuck into the baggage hold before they closed it up. At the time some health care experts said it was possible for the body to go into a hibernation like state and survive (especially if the wheel well didn't get all that cold - heated from the surrounding airplane), but that in most cases the person wouldn't wake up in time to avoid fall out when they lowered the gear.
