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A B-737 flight crew descended through clearance altitude citing distraction, a nonstandard autoplt, and PNF's loss of situational awareness as contributing factors.
| Attributes | |
| ACN | 302499 |
| Time | |
| Date | 199504 |
| Day | Tue |
| Local Time Of Day | 0601 To 1200 |
| Place | |
| Locale Reference | atc facility : rod |
| State Reference | OH |
| Altitude | msl bound lower : 15300 msl bound upper : 16000 |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Controlling Facilities | artcc : zob |
| Operator | common carrier : air carrier |
| Make Model Name | B737 Undifferentiated or Other Model |
| Operating Under FAR Part | Part 121 |
| Flight Phase | descent other |
| Route In Use | enroute : on vectors enroute airway : zob |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : atp pilot : flight engineer |
| Experience | flight time last 90 days : 180 flight time total : 14000 flight time type : 3000 |
| ASRS Report | 302499 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Experience | flight time last 90 days : 210 flight time total : 10500 flight time type : 630 |
| ASRS Report | 302390 |
| Events | |
| Anomaly | aircraft equipment problem : critical altitude deviation : overshoot inflight encounter : weather non adherence : clearance other anomaly other |
| Independent Detector | 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:
On departure climb from stl to cle we experienced left wing body overheat light. Ran checklist, isolated left side of pneumatic system and closed #1 engine bleed. Stopped climb 25000 ft (1 pack). In cruise, aircraft was not maintaining pressurization. Cabin at 9000 ft and climbing slowly. We asked for lower altitude and began a series of step-down dscnts. We were given left 15 degrees and descent to 16000 ft from 17000 ft. The heading took us into area of precipitation. Captain was on the PA. Then I turned, started descent and reached over to adjust radar picture. I was concerned about icing and our inability to shed ice off left wing due to our set-up on pneumatics. Preoccupied with radar, failed to level at 16000 ft and caught altitude at 15300 ft. Immediately climbed back to 16000 ft. This aircraft does not have altitude capture feature on autoplt. Some aircraft do, some do not. Nonstandard fleet. Contributing factors for the altitude bust: 1) captain not in the loop. 2) failure of PF to monitor descent. 3) nonstandard autoplt. Supplemental information from acn 302390: controller gave a turn to expedite descent and I went off to make PA to passenger at 18000 ft prior to initiation of sterile cockpit. Copilot was looking at radar and passed through 16000 ft. Company has B-737-100/200 in fleet. Some have altitude select function on autoplt, some do not. This aircraft did not.
Original NASA ASRS Text
Title: A B-737 FLC DSNDED THROUGH CLRNC ALT CITING DISTR, A NONSTANDARD AUTOPLT, AND PNF'S LOSS OF SITUATIONAL AWARENESS AS CONTRIBUTING FACTORS.
Narrative: ON DEP CLB FROM STL TO CLE WE EXPERIENCED L WING BODY OVERHEAT LIGHT. RAN CHKLIST, ISOLATED L SIDE OF PNEUMATIC SYS AND CLOSED #1 ENG BLEED. STOPPED CLB 25000 FT (1 PACK). IN CRUISE, ACFT WAS NOT MAINTAINING PRESSURIZATION. CABIN AT 9000 FT AND CLBING SLOWLY. WE ASKED FOR LOWER ALT AND BEGAN A SERIES OF STEP-DOWN DSCNTS. WE WERE GIVEN L 15 DEGS AND DSCNT TO 16000 FT FROM 17000 FT. THE HDG TOOK US INTO AREA OF PRECIPITATION. CAPT WAS ON THE PA. THEN I TURNED, STARTED DSCNT AND REACHED OVER TO ADJUST RADAR PICTURE. I WAS CONCERNED ABOUT ICING AND OUR INABILITY TO SHED ICE OFF L WING DUE TO OUR SET-UP ON PNEUMATICS. PREOCCUPIED WITH RADAR, FAILED TO LEVEL AT 16000 FT AND CAUGHT ALT AT 15300 FT. IMMEDIATELY CLBED BACK TO 16000 FT. THIS ACFT DOES NOT HAVE ALT CAPTURE FEATURE ON AUTOPLT. SOME ACFT DO, SOME DO NOT. NONSTANDARD FLEET. CONTRIBUTING FACTORS FOR THE ALT BUST: 1) CAPT NOT IN THE LOOP. 2) FAILURE OF PF TO MONITOR DSCNT. 3) NONSTANDARD AUTOPLT. SUPPLEMENTAL INFO FROM ACN 302390: CTLR GAVE A TURN TO EXPEDITE DSCNT AND I WENT OFF TO MAKE PA TO PAX AT 18000 FT PRIOR TO INITIATION OF STERILE COCKPIT. COPLT WAS LOOKING AT RADAR AND PASSED THROUGH 16000 FT. COMPANY HAS B-737-100/200 IN FLEET. SOME HAVE ALT SELECT FUNCTION ON AUTOPLT, SOME DO NOT. THIS ACFT DID NOT.
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.