Narrative:

The incident occurred during the initial descent phase for landing at brownsville, tx. Descent instructions were received at FL330 with step-down to FL230, FL190, and 16000 ft before the incident took place. When the clearance to 16000 ft was received, I, the PNF, acknowledged and dialed the correct altitude on the altitude alerter. The captain acknowledged by stating '16000 ft' and pointing to the altitude alerter. Shortly thereafter, the captain briefed the approach and called for the descent checklist. While I was involved with the execution of the checklist, the center controller alerted us to our altitude deviation, at which time we had already descended to approximately 14500 ft. The center controller did not seem overly concerned with the incident as there were no other aircraft in the vicinity. Instead, after a short pause, he assigned us a descent to 6000 ft. Contributing factors included noise level, automation, distraction, and fatigue. The noise level in this particular aircraft is significant due to its age and the removal of insulation in the main cabin. We were unable to hear the aural alert or see the amber light. Automation, or lack of it, played an important role in this incident. Both, the captain and I came to our present employer from aircraft that incorporated fully automated (altitude capture) glass cockpits. Additionally, our involvement with the checklist drew our attention away from our assigned altitude. But the major contributing factor to the incident was fatigue. After arriving at chicago at XA30, checking into a hotel at XB00, and getting a wake-up call at XE00 to report for duty at XH00 in detroit, the captain had been given an 'opportunity' to rest for only 3 hours during the preceding 24 hours. Although he acknowledged the clearance to 16000 ft, his cognitive awareness led him to believe that the assigned altitude was 11000 ft.

Google
 

Original NASA ASRS Text

Title: DC9 CREW EXPERIENCED AN ALTDEV IN ZHU CLASS E.

Narrative: THE INCIDENT OCCURRED DURING THE INITIAL DSCNT PHASE FOR LNDG AT BROWNSVILLE, TX. DSCNT INSTRUCTIONS WERE RECEIVED AT FL330 WITH STEP-DOWN TO FL230, FL190, AND 16000 FT BEFORE THE INCIDENT TOOK PLACE. WHEN THE CLRNC TO 16000 FT WAS RECEIVED, I, THE PNF, ACKNOWLEDGED AND DIALED THE CORRECT ALT ON THE ALT ALERTER. THE CAPT ACKNOWLEDGED BY STATING '16000 FT' AND POINTING TO THE ALT ALERTER. SHORTLY THEREAFTER, THE CAPT BRIEFED THE APCH AND CALLED FOR THE DSCNT CHKLIST. WHILE I WAS INVOLVED WITH THE EXECUTION OF THE CHKLIST, THE CTR CTLR ALERTED US TO OUR ALTDEV, AT WHICH TIME WE HAD ALREADY DSNDED TO APPROX 14500 FT. THE CTR CTLR DID NOT SEEM OVERLY CONCERNED WITH THE INCIDENT AS THERE WERE NO OTHER ACFT IN THE VICINITY. INSTEAD, AFTER A SHORT PAUSE, HE ASSIGNED US A DSCNT TO 6000 FT. CONTRIBUTING FACTORS INCLUDED NOISE LEVEL, AUTOMATION, DISTR, AND FATIGUE. THE NOISE LEVEL IN THIS PARTICULAR ACFT IS SIGNIFICANT DUE TO ITS AGE AND THE REMOVAL OF INSULATION IN THE MAIN CABIN. WE WERE UNABLE TO HEAR THE AURAL ALERT OR SEE THE AMBER LIGHT. AUTOMATION, OR LACK OF IT, PLAYED AN IMPORTANT ROLE IN THIS INCIDENT. BOTH, THE CAPT AND I CAME TO OUR PRESENT EMPLOYER FROM ACFT THAT INCORPORATED FULLY AUTOMATED (ALT CAPTURE) GLASS COCKPITS. ADDITIONALLY, OUR INVOLVEMENT WITH THE CHKLIST DREW OUR ATTN AWAY FROM OUR ASSIGNED ALT. BUT THE MAJOR CONTRIBUTING FACTOR TO THE INCIDENT WAS FATIGUE. AFTER ARRIVING AT CHICAGO AT XA30, CHKING INTO A HOTEL AT XB00, AND GETTING A WAKE-UP CALL AT XE00 TO RPT FOR DUTY AT XH00 IN DETROIT, THE CAPT HAD BEEN GIVEN AN 'OPPORTUNITY' TO REST FOR ONLY 3 HRS DURING THE PRECEDING 24 HRS. ALTHOUGH HE ACKNOWLEDGED THE CLRNC TO 16000 FT, HIS COGNITIVE AWARENESS LED HIM TO BELIEVE THAT THE ASSIGNED ALT WAS 11000 FT.

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.