As ICM said, things are a lot less dramatic than the movies would have you believe. I've done both an explosive decompression test and the one where your oxygen is cut off and you gradually become hypoxic. One thing is common to both scenarios - full consciousness returns very quickly once oxygen supply has been restored, usually within the time it takes to take several breaths. Films would have you believe that occupants will be gasping and clutching at their throats for an age - that is simply not the case. No experience of the C5 but the principle is essentially the same for any aircraft.