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An air carrier B757 flight crew descended below their assigned altitude when the flight crew misset the altitude alerter.
| Attributes | |
| ACN | 389030 |
| Time | |
| Date | 199712 |
| Day | Fri |
| Local Time Of Day | 1801 To 2400 |
| Place | |
| Locale Reference | atc facility : pxr |
| State Reference | AZ |
| Altitude | msl bound lower : 11300 msl bound upper : 12000 |
| Environment | |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | artcc : zab |
| Operator | common carrier : air carrier |
| Make Model Name | B757 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | Other Other |
| Flight Phase | descent other |
| Route In Use | arrival other arrival star : star |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| ASRS Report | 389030 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : commercial pilot : instrument |
| Events | |
| Anomaly | altitude deviation : overshoot non adherence : far non adherence : clearance |
| Independent Detector | aircraft equipment other aircraft equipment : unspecified other flight crewa |
| Resolutory Action | flight crew : returned to intended course or assigned course |
| Consequence | Other |
| Supplementary | |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Cruising at FL260 ZAB gave us a clearance to cross tonto intersection at 250 KTS and 12000 ft. We were going to intercept the arrival inside tonto and after clearance was changed to direct tonto, PNF went off the air to get ATIS. The altitude select window was not changed and the PF did not catch it. The PF tried to start a descent and discovered the altitude select was still at FL260. The PF reset the altitude select to 11000 ft incorrectly and began descent. Passing 11600 ft, the PNF said he thought the clearance was 12000 ft. Autoplt was disconnected and climb was started back to 12000 ft. The aircraft bottomed at 11300 ft. Approach was contacted and no conflict resulted. Failure to adhere to established altitude select procedures resulted in this altitude bust.
Original NASA ASRS Text
Title: AN ACR B757 FLC DSNDED BELOW THEIR ASSIGNED ALT WHEN THE FLC MISSET THE ALT ALERTER.
Narrative: CRUISING AT FL260 ZAB GAVE US A CLRNC TO CROSS TONTO INTXN AT 250 KTS AND 12000 FT. WE WERE GOING TO INTERCEPT THE ARR INSIDE TONTO AND AFTER CLRNC WAS CHANGED TO DIRECT TONTO, PNF WENT OFF THE AIR TO GET ATIS. THE ALT SELECT WINDOW WAS NOT CHANGED AND THE PF DID NOT CATCH IT. THE PF TRIED TO START A DSCNT AND DISCOVERED THE ALT SELECT WAS STILL AT FL260. THE PF RESET THE ALT SELECT TO 11000 FT INCORRECTLY AND BEGAN DSCNT. PASSING 11600 FT, THE PNF SAID HE THOUGHT THE CLRNC WAS 12000 FT. AUTOPLT WAS DISCONNECTED AND CLB WAS STARTED BACK TO 12000 FT. THE ACFT BOTTOMED AT 11300 FT. APCH WAS CONTACTED AND NO CONFLICT RESULTED. FAILURE TO ADHERE TO ESTABLISHED ALT SELECT PROCS RESULTED IN THIS ALT BUST.
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.