Narrative:

We were inbound to bld VOR, the MCP (mode control panel) of the autoplt was set to command level change and the altitude selected for level off was ATC assigned 15000'. At the time, I was deviating around some big cumulus in moderate turbulence, getting knocked around, quite alot. My scan was in and out of the cockpit, shifting from the EFIS radar display to the visibility situation outside. We had completed our descent approach checklist prior to 18000' and shortly thereafter ATC called traffic at 12 O'clock, both of us were looking outside for this traffic when ATC asked to verify our altitude. My altimeter was approximately 15500' and the first officer's was the correct 14500', we adjusted our altitude and the traffic was never seen. The problem was that I had set in 30.41 instead of 29.41. The reasons for the mistake was that given the workload at the time, deviating around buildups in moderate turbulence I read or saw the .41 in the first officer's altimeter and called xchk in the approach checklist. I usually lean over to the right, to get a better angle of view on the instrument, but given the workload I omitted this usual practice. Another factor that would alleviate this problem would be to give the local altimeter settings in millibars instead of inches. Callback conversation with reporter revealed the following information. Reporter called to verify when immunity starts, from postmark or receipt date, analyst explained that from postmark. Reporter admitted he had misset his altimeter thus making him low at the time approach control questioned him. Aircraft was in severe turbulence and reporter said cockpit very busy plus cockpit crew concerned about passenger and F/as being seated. Traffic was another air carrier on departure route and neither saw the other, however the conflict alert was activated and FAA is pursuing the incident. Flight crew talked with TRACON supervisor who said they would not press any charges, but suspect the ARTCC oedp program caught the error which resulted in the investigation.

Google
 

Original NASA ASRS Text

Title: MLG DESCENDING IN MODERATE TO SEVERE TURBULENCE, MISSET ALTIMETER AND BUSTED ALT CAUSING A LESS THAN STANDARD SEPARATION INCIDENT.

Narrative: WE WERE INBND TO BLD VOR, THE MCP (MODE CTL PANEL) OF THE AUTOPLT WAS SET TO COMMAND LEVEL CHANGE AND THE ALT SELECTED FOR LEVEL OFF WAS ATC ASSIGNED 15000'. AT THE TIME, I WAS DEVIATING AROUND SOME BIG CUMULUS IN MODERATE TURB, GETTING KNOCKED AROUND, QUITE ALOT. MY SCAN WAS IN AND OUT OF THE COCKPIT, SHIFTING FROM THE EFIS RADAR DISPLAY TO THE VIS SITUATION OUTSIDE. WE HAD COMPLETED OUR DSNT APCH CHKLIST PRIOR TO 18000' AND SHORTLY THEREAFTER ATC CALLED TFC AT 12 O'CLOCK, BOTH OF US WERE LOOKING OUTSIDE FOR THIS TFC WHEN ATC ASKED TO VERIFY OUR ALT. MY ALTIMETER WAS APPROX 15500' AND THE F/O'S WAS THE CORRECT 14500', WE ADJUSTED OUR ALT AND THE TFC WAS NEVER SEEN. THE PROB WAS THAT I HAD SET IN 30.41 INSTEAD OF 29.41. THE REASONS FOR THE MISTAKE WAS THAT GIVEN THE WORKLOAD AT THE TIME, DEVIATING AROUND BUILDUPS IN MODERATE TURB I READ OR SAW THE .41 IN THE F/O'S ALTIMETER AND CALLED XCHK IN THE APCH CHKLIST. I USUALLY LEAN OVER TO THE R, TO GET A BETTER ANGLE OF VIEW ON THE INSTRUMENT, BUT GIVEN THE WORKLOAD I OMITTED THIS USUAL PRACTICE. ANOTHER FACTOR THAT WOULD ALLEVIATE THIS PROB WOULD BE TO GIVE THE LCL ALTIMETER SETTINGS IN MILLIBARS INSTEAD OF INCHES. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO. RPTR CALLED TO VERIFY WHEN IMMUNITY STARTS, FROM POSTMARK OR RECEIPT DATE, ANALYST EXPLAINED THAT FROM POSTMARK. RPTR ADMITTED HE HAD MISSET HIS ALTIMETER THUS MAKING HIM LOW AT THE TIME APCH CTL QUESTIONED HIM. ACFT WAS IN SEVERE TURB AND RPTR SAID COCKPIT VERY BUSY PLUS COCKPIT CREW CONCERNED ABOUT PAX AND F/AS BEING SEATED. TFC WAS ANOTHER ACR ON DEP RTE AND NEITHER SAW THE OTHER, HOWEVER THE CONFLICT ALERT WAS ACTIVATED AND FAA IS PURSUING THE INCIDENT. FLT CREW TALKED WITH TRACON SUPVR WHO SAID THEY WOULD NOT PRESS ANY CHARGES, BUT SUSPECT THE ARTCC OEDP PROGRAM CAUGHT THE ERROR WHICH RESULTED IN THE INVESTIGATION.

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.