Late developer,
Just some background info on the pax oxy masks in the 737.
The flow of oxygen in the pax oxy masks will not start until you pull sharply down on one of your individual group of 3 or 4 masks. This little snippet of info is one of the reasons why the cabin crew do a safety demo before every flight.
There are a couple of good reasons why the oxy does not flow until pulled:
1. In case the oxy masks were deployed accidentally (wrong switch or heavy landing) you would then have no oxy left if you needed it.
2. If the flight were not full it would introduce large amounts of oxy into the cabin which would be a fire risk.
It should be noted that any unpulled masks give the cabin crew to option to “monkey swing” around the cabin without portable oxy if reqd. This may be what the cabin crew member in the flight deck did to extend his time of useful consciousness.
The spare 10% is usually achieved by having 3 masks on one side and 4 on the other, this allows for infants carried on parents knees. It is also to allow for either a unit not dropping out or a unit not producing oxygen when demanded. In my experience at least one group of oxy masks do not drop when demanded, sometimes more. Even if there were only one pax in each seat block who had activated their oxy then there would be no more spares (other than those in the galley & toilets) because pulling one mask activates all the masks in the group.
S&L
Last edited by CaptainSandL; 25th Oct 2006 at 08:44.
Reason: monkey walk changed to monkey swing