B737-900
Flight Crew Air Transport Pilot (ATP)
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Overcame Equipment Problem; General Maintenance Action
Aircraft; Procedure
First officer's O2 mask hose sprung a pressurized leak.  I had him disconnect the mask from its system supply hose to stop the leak and eliminate the possibly of an O2 fed cockpit fire. I further instructed him to swap out the 1st observer's O2 so he would have smoke protection as well as O2 in case of a decompression and to continue the flight to the destination.  I used my captain's emergency authority to perform these procedures.
When the First Officer's oxygen mask hose failed; the Captain directed him to replace it with an observer's mask so that the oxygen system would be available if needed.