Well, duh

The Register out of the UK has an article by Lester Haines about the Columbia shuttle disaster:

NASA's comprehensive final Columbia Crew Survival Investigation Report has concluded that the 1 February 2003 space shuttle disaster was "not survivable by any currently existing capability". Columbia distintegrated on re-entry into Earth's atmosphere, having suffered launch damage to its left wing caused by a piece of foam which detached from the external fuel tank. Hot gas entering the breach provoked a catastrophic meltdown of the shuttle's structure, although the report reveals the crew were killed not by fire but rather by a "depressurization event" which "occurred so rapidly that the crew members were incapacitated within seconds".
The 400-page report notes that some crew members were not wearing their protective gloves at the time of the "Crew Module Catastrophic Event (CMCE)", one was not wearing a helmet and the six who were had their visors open.
Accordingly, although NASA says the crew was aware of the initial "LOC [loss of control] and was taking actions that were consistent with an attempt to recover hydraulic pressure", the cabin depressurisation proved "lethal". Had the crew survived the loss of pressure, they would have been killed anyway by injuries caused by "inadequate upper body restraint and protection during rotational motion", possible exposure to "thermal events" and, finally, "ground impact".
Specifically regarding these three factors, NASA explains that "seat inertial reel mechanisms on the crews’ shoulder harnesses did not lock", the "ascent and entry suit had no performance requirements for occupant protection from thermal events" and the suit "provides protection from ground impact with a parachute system" which had to be manually operated. Its recommendations are that "future spacecraft seats and suits should be integrated to ensure proper restraint of the crew in off-nominal situations while not affecting operational performance", and that "spacecraft crew survival systems should not rely on manual activation to protect the crew". Regarding a "thermal event", NASA soberly concludes that "the only known complete protection from this... would be to prevent its occurrence". NASA deputy associate administrator Wayne Hale summarised: "This report confirms that although the valiant Columbia crew tried every possible way to maintain control of their vehicle, the accident was not ultimately survivable."

Rico says that, if you click on the post title and go to the article, you can download the complete report; probably fascinating reading, if macabre...