Narrative:

If you are keeping records on automation complacency this is another occurrence. I have spent the last three yrs as an large transport captain. The large transport will automatically capture the altitude selected on its mode control panel west/O the necessity of arming. Being a new widebody transport captain (approximately 22 hours widebody transport time) I fell into an automation difference between the two aircraft. I was cleared by ZMP to descend to FL240. My first officer was out of the cockpit taking care of personal physiological needs. The autoplt was engaged, I selected FL240 on the altitude select window and started an IAS (indicated airspeed) descent. When I selected FL240 I should have armed the altitude capture mode but after three yrs of having this done automatically on the large transport, I forgot to make the selection. Descending through approximately FL260, I was distraction by my first officer returning to the cockpit. As he was buckling into his seat, he noticed we were passing through the selected altitude (about 23000'). Immediately, I started a climb back to FL240 and at the same time my first officer turned off our transponder. His intent in turning off the transponder was to protect his captain from the possible consequences of this altitude deviation. To the best of my knowledge ZMP did not detect this deviation because nothing was said to indicate their knowing. After much thought and agonizing, I consulted with three other company capts and was very surprised to find that two of the three had similar experiences. The common thread to all three was a combination of an error in automation selection combined with a distraction at a critical time. In conclusion, I would like to express my thanks for this confidential forum to relay information that I hope can be used for the promotion of aviation safety. I am not proud of my actions in this occurrence but I hope that my indiscretion can be used for a positive purpose. It is my sincere opinion that automation is an asset, but it requires a special effort to maintain vigilance.

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Original NASA ASRS Text

Title: CAPT OF WDB DESCENDS THROUGH ASSIGNED ALT WHILE FO IS OUT OF COCKPIT DUE TO CAPT'S FAILING TO ARM THE ALT CAPTURE ON THE AUTOPLT. FO RETURNS AND SPOTS ALT DEVIATION, THEN TURNS OFF TRANSPONDER TO COVER UP THE MISTAKE WHILE THE CAPT CORRECTS BACK TO THE PROPER ALT.

Narrative: IF YOU ARE KEEPING RECORDS ON AUTOMATION COMPLACENCY THIS IS ANOTHER OCCURRENCE. I HAVE SPENT THE LAST THREE YRS AS AN LGT CAPT. THE LGT WILL AUTOMATICALLY CAPTURE THE ALT SELECTED ON ITS MODE CTL PANEL W/O THE NECESSITY OF ARMING. BEING A NEW WDB CAPT (APPROX 22 HRS WDB TIME) I FELL INTO AN AUTOMATION DIFFERENCE BTWN THE TWO ACFT. I WAS CLRED BY ZMP TO DSND TO FL240. MY F/O WAS OUT OF THE COCKPIT TAKING CARE OF PERSONAL PHYSIOLOGICAL NEEDS. THE AUTOPLT WAS ENGAGED, I SELECTED FL240 ON THE ALT SELECT WINDOW AND STARTED AN IAS (INDICATED AIRSPD) DSNT. WHEN I SELECTED FL240 I SHOULD HAVE ARMED THE ALT CAPTURE MODE BUT AFTER THREE YRS OF HAVING THIS DONE AUTOMATICALLY ON THE LGT, I FORGOT TO MAKE THE SELECTION. DSNDING THROUGH APPROX FL260, I WAS DISTR BY MY F/O RETURNING TO THE COCKPIT. AS HE WAS BUCKLING INTO HIS SEAT, HE NOTICED WE WERE PASSING THROUGH THE SELECTED ALT (ABOUT 23000'). IMMEDIATELY, I STARTED A CLB BACK TO FL240 AND AT THE SAME TIME MY F/O TURNED OFF OUR TRANSPONDER. HIS INTENT IN TURNING OFF THE TRANSPONDER WAS TO PROTECT HIS CAPT FROM THE POSSIBLE CONSEQUENCES OF THIS ALT DEVIATION. TO THE BEST OF MY KNOWLEDGE ZMP DID NOT DETECT THIS DEVIATION BECAUSE NOTHING WAS SAID TO INDICATE THEIR KNOWING. AFTER MUCH THOUGHT AND AGONIZING, I CONSULTED WITH THREE OTHER COMPANY CAPTS AND WAS VERY SURPRISED TO FIND THAT TWO OF THE THREE HAD SIMILAR EXPERIENCES. THE COMMON THREAD TO ALL THREE WAS A COMBINATION OF AN ERROR IN AUTOMATION SELECTION COMBINED WITH A DISTR AT A CRITICAL TIME. IN CONCLUSION, I WOULD LIKE TO EXPRESS MY THANKS FOR THIS CONFIDENTIAL FORUM TO RELAY INFO THAT I HOPE CAN BE USED FOR THE PROMOTION OF AVIATION SAFETY. I AM NOT PROUD OF MY ACTIONS IN THIS OCCURRENCE BUT I HOPE THAT MY INDISCRETION CAN BE USED FOR A POSITIVE PURPOSE. IT IS MY SINCERE OPINION THAT AUTOMATION IS AN ASSET, BUT IT REQUIRES A SPECIAL EFFORT TO MAINTAIN VIGILANCE.

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.