Narrative:

Departed bda. Passing FL345 the door light on the master warning panel flashed on/off numerous times. On level off at FL350, it changed from flashing to a steady light. Seconds later, the door light (#4 right) came on (on second officer panel, 2 separate warning systems). I was flying the aircraft from takeoff and the captain and second officer worked the problem. The captain called for O2 and we established interphone communications. There was a question whether we had control of the cabin pressure and it was decided to descend to a lower altitude. Simultaneously, I began a descent out of FL350 and the captain attempted contacting bda control on VHF radio. I believe he attempted 2 contacts with no success and switched to HF radio. While he was talking to ny oceanic, bda control responded. I declared an emergency and advised I was descending. We were cleared to 5000'. During the initial part of the descent, it was determined that we did have control of the cabin pressure and the door lights checklist was completed. We continued descent and returned to bda. During the initial part of the descent the transponder code was inadvertently set to 7500. I do not recall whether we were queried about this setting until we were on the ground, at which time we recognized our error. Cause for transponder error was mental lapse in setting wrong code, and lack of backup by other crew members in not noticing the error.

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Original NASA ASRS Text

Title: ACR WDB GOT A DOOR WARNING JUST BEFORE REACHING CRUISE ALT OF FL350. DOOR WAS IDENTIFIED BUT FLT CREW SAYS VISUAL DOOR CHECK WAS NOT CONCLUSIVE SO RETURN LAND. AERIAL PIRACY CODE SET IN TRANSPONDER BY MISTAKE.

Narrative: DEPARTED BDA. PASSING FL345 THE DOOR LIGHT ON THE MASTER WARNING PANEL FLASHED ON/OFF NUMEROUS TIMES. ON LEVEL OFF AT FL350, IT CHANGED FROM FLASHING TO A STEADY LIGHT. SECS LATER, THE DOOR LIGHT (#4 RIGHT) CAME ON (ON S/O PANEL, 2 SEPARATE WARNING SYSTEMS). I WAS FLYING THE ACFT FROM TKOF AND THE CAPT AND S/O WORKED THE PROB. THE CAPT CALLED FOR O2 AND WE ESTABLISHED INTERPHONE COMS. THERE WAS A QUESTION WHETHER WE HAD CTL OF THE CABIN PRESSURE AND IT WAS DECIDED TO DSND TO A LOWER ALT. SIMULTANEOUSLY, I BEGAN A DSNT OUT OF FL350 AND THE CAPT ATTEMPTED CONTACTING BDA CTL ON VHF RADIO. I BELIEVE HE ATTEMPTED 2 CONTACTS WITH NO SUCCESS AND SWITCHED TO HF RADIO. WHILE HE WAS TALKING TO NY OCEANIC, BDA CTL RESPONDED. I DECLARED AN EMER AND ADVISED I WAS DSNDING. WE WERE CLRED TO 5000'. DURING THE INITIAL PART OF THE DSNT, IT WAS DETERMINED THAT WE DID HAVE CTL OF THE CABIN PRESSURE AND THE DOOR LIGHTS CHKLIST WAS COMPLETED. WE CONTINUED DSNT AND RETURNED TO BDA. DURING THE INITIAL PART OF THE DSNT THE XPONDER CODE WAS INADVERTENTLY SET TO 7500. I DO NOT RECALL WHETHER WE WERE QUERIED ABOUT THIS SETTING UNTIL WE WERE ON THE GND, AT WHICH TIME WE RECOGNIZED OUR ERROR. CAUSE FOR XPONDER ERROR WAS MENTAL LAPSE IN SETTING WRONG CODE, AND LACK OF BACKUP BY OTHER CREW MEMBERS IN NOT NOTICING THE ERROR.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.