A B737 WAS DISPATCHED IN NON COMPLIANCE WITH THE PAX OXYGEN ON LIGHT ON THE OVERHEAD P-5 PANEL DEFERRED AS INOP IN CONFLICT WITH THE MEL.

Narrative

I WAS WORKING DESK XX WHILE ANOTHER DISPATCHER STEPPED AWAY FOR A MOMENT. I ANSWERED THE PHONE AND THE CAPT WAS ON THE PHONE IN XX (A MAINT STATION). HE INFORMED ME THAT A MAINT WORKER HAD TALKED TO MAINT CTLR AND WERE DEFERRING THE OVERHEAD LIGHT FOR THE PAX OXYGEN SYS. I GAVE THE CAPT THE TIME AND MY INITIALS FOR THE DEFERRAL (COCKPIT INST LIGHT). I CALLED MAINT AND THEY TOLD ME THAT THE BACK-UP FOR THE LIGHT IS THE 6 PACK. THAT SAME CREW TOOK THAT ACFT XXX-YYY WHERE IT WAS PICKED UP BY ANOTHER CREW. THE NEW CREW DISAGREED WITH THAT DEFERRAL; BECAUSE THE MEL DOES NOT SPECIFICALLY STATE THAT THE ITEM CAN BE DEFERRED. ON THE PRIOR AGREEMENT WITH THE CAPT AND MAINT THE JUSTIFICATION WAS THAT A BACK-UP (6 PACK) WAS SUFFICIENT UNDER THE DESCRIPTION OF DEFERRAL. XXX SENT PARTS AND MECHS OUT TO YYY TO FIX WARNING LIGHT (OXYGEN OVERHEAD); AND THE PLANE WAS BACK IN SVC LATER THAT EVENING. POSSIBLY A CHANGE IN THE MEL TO AVERT ANY OTHER GREY AREAS CONCERNING WHICH LIGHTS ARE COVERED BY THIS DEFERRAL. ALSO INCLUDING ALL 3 (CAPT; DISPATCHER; MAINT CTL) PERSONS ON THE CONFERENCE ALL AT A MAINT STATION; JUST AS IT IS DONE IN AN OUT STATION. THAT WAY THERE IS NO TRANSPORTING OR SECOND HAND INFO.