Narrative:

Scheduled flight abcd sea-oak. Captain was PF, I was PNF handling radios. I am in my first yr with my air carrier and it was my first trip to/from sea. During climb out, out of approximately 12000 ft, I informed captain I would be off communication #1 to call back times to sea. He acknowledged (this is SOP). While I was on company frequency communication #2, I was contacted by another company aircraft. They requested that I pass on a customer service request to sea operations. The message was quite extensive and detailed, and there was also some confusion regarding details. It took some time and several relay calls to complete. At least once during this time, I briefed the captain on what I was doing, and verified that he wanted me to continue offering assistance. He did. When I returned to communication #1 and normal duties, it had been 10-15 mins and we were leveling at FL330. I had lost some situational awareness and he briefed me on our position and last clearance. He left communication #1 to make passenger PA (SOP) and turn off seat belt sign. While he was gone, ATC questioned our altitude. In fact, I had difficulty understanding what the controller was saying, and on the third attempt he stated 'mode C shows you at FL336.' both altimeters showed FL330, however, I then noticed that no altimeter had been reset to 29.92 at FL180. When set standard, we were at FL336. At this time, the captain came back and we descended to FL330. Nothing more was said by ATC, no other aircraft were involved or issued deviations, nor were we given any deviations. No aircraft on TCASII. I think the captain had been distraction listening in on communication #2 and forgot to set standard altimeter at FL180. I was out of the loop and distraction when we passed FL180. I've now added to my leveloff mental checklist to verify altimeter setting as well as altitude.

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Original NASA ASRS Text

Title: B737 CREW HAD ALT EXCURSION.

Narrative: SCHEDULED FLT ABCD SEA-OAK. CAPT WAS PF, I WAS PNF HANDLING RADIOS. I AM IN MY FIRST YR WITH MY ACR AND IT WAS MY FIRST TRIP TO/FROM SEA. DURING CLBOUT, OUT OF APPROX 12000 FT, I INFORMED CAPT I WOULD BE OFF COM #1 TO CALL BACK TIMES TO SEA. HE ACKNOWLEDGED (THIS IS SOP). WHILE I WAS ON COMPANY FREQ COM #2, I WAS CONTACTED BY ANOTHER COMPANY ACFT. THEY REQUESTED THAT I PASS ON A CUSTOMER SVC REQUEST TO SEA OPS. THE MESSAGE WAS QUITE EXTENSIVE AND DETAILED, AND THERE WAS ALSO SOME CONFUSION REGARDING DETAILS. IT TOOK SOME TIME AND SEVERAL RELAY CALLS TO COMPLETE. AT LEAST ONCE DURING THIS TIME, I BRIEFED THE CAPT ON WHAT I WAS DOING, AND VERIFIED THAT HE WANTED ME TO CONTINUE OFFERING ASSISTANCE. HE DID. WHEN I RETURNED TO COM #1 AND NORMAL DUTIES, IT HAD BEEN 10-15 MINS AND WE WERE LEVELING AT FL330. I HAD LOST SOME SITUATIONAL AWARENESS AND HE BRIEFED ME ON OUR POS AND LAST CLRNC. HE LEFT COM #1 TO MAKE PAX PA (SOP) AND TURN OFF SEAT BELT SIGN. WHILE HE WAS GONE, ATC QUESTIONED OUR ALT. IN FACT, I HAD DIFFICULTY UNDERSTANDING WHAT THE CTLR WAS SAYING, AND ON THE THIRD ATTEMPT HE STATED 'MODE C SHOWS YOU AT FL336.' BOTH ALTIMETERS SHOWED FL330, HOWEVER, I THEN NOTICED THAT NO ALTIMETER HAD BEEN RESET TO 29.92 AT FL180. WHEN SET STANDARD, WE WERE AT FL336. AT THIS TIME, THE CAPT CAME BACK AND WE DSNDED TO FL330. NOTHING MORE WAS SAID BY ATC, NO OTHER ACFT WERE INVOLVED OR ISSUED DEVS, NOR WERE WE GIVEN ANY DEVS. NO ACFT ON TCASII. I THINK THE CAPT HAD BEEN DISTR LISTENING IN ON COM #2 AND FORGOT TO SET STANDARD ALTIMETER AT FL180. I WAS OUT OF THE LOOP AND DISTR WHEN WE PASSED FL180. I'VE NOW ADDED TO MY LEVELOFF MENTAL CHKLIST TO VERIFY ALTIMETER SETTING AS WELL AS ALT.

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.