Space Shuttle Challenger disaster
The pressure suits the crew wore, introduced after the 
, were criticised as the crew could not keep their visors down throughout re-entry due to a design limitation that would have caused excess levels of oxygen to be present had they done so, leaving the suits unsealed. The gloves also made many tasks difficult or impossible. When the accident occurred, three people were not wearing gloves, one was not wearing a helmet, and none had their visors down. The helmets also did not conform to the heads of the wearers.
NASA issues survivability report on Columbia crash