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A B737-300 climbs 400 ft above its assigned altitude when the first officer's misprogramming of the MCP causes the altitude hold to disengage.
| Attributes | |
| ACN | 429340 |
| Time | |
| Date | 199902 |
| Day | Fri |
| Local Time Of Day | 1201 To 1800 |
| Place | |
| Locale Reference | atc facility : zau.artcc |
| State Reference | IL |
| Altitude | msl bound lower : 28000 msl bound upper : 28400 |
| Environment | |
| Flight Conditions | VMC |
| Light | Night |
| Aircraft 1 | |
| Controlling Facilities | artcc : zau.artcc |
| Operator | common carrier : air carrier |
| Make Model Name | B737-300 |
| Operating Under FAR Part | Part 121 |
| Navigation In Use | other |
| Flight Phase | cruise : level |
| Route In Use | enroute airway : ns.airway |
| Flight Plan | IFR |
| Person 1 | |
| Affiliation | company : air carrier |
| Function | flight crew : first officer |
| Qualification | pilot : instrument pilot : multi engine pilot : atp pilot : cfi |
| Experience | flight time last 90 days : 200 flight time total : 11000 flight time type : 200 |
| ASRS Report | 729340 |
| Person 2 | |
| Affiliation | company : air carrier |
| Function | flight crew : captain oversight : pic |
| Qualification | pilot : atp |
| Events | |
| Anomaly | altitude deviation : excursion from assigned altitude non adherence : company policies non adherence : published procedure other anomaly other anomaly other |
| Independent Detector | other flight crewa |
| Resolutory Action | flight crew : returned to original clearance flight crew : became reoriented |
| Supplementary | |
| Problem Areas | Flight Crew Human Performance |
| Primary Problem | Flight Crew Human Performance |
| Air Traffic Incident | Pilot Deviation |
Narrative:
Level cruise at FL280, we received a new altitude of FL200 with crossing restr, and speed increase to 320 KTS when able. Autoplt was on. While captain programmed the FMC for the crossing and speed increase, I elected to manually select a higher mach number in the master control panel window to expedite the speed increase to help accommodate ATC. In doing so, I inadvertently caused the 'altitude hold' mode to disengage since a new crossing altitude had been set in the MCP window (FL200). This autoplt and FMC are new to me, and while I observed the captain completing the FMC programming, the aircraft began a slow climb. I allowed myself to be distraction, failed to monitor the autoplt during this short period, and subsequently did not catch the altitude deviation. The captain alerted me and stopped the climb approximately 300-400 ft high. There was no conflict with another aircraft, no TA/RA, nor was there a call from ATC. (I was reminded how to never rely on automation, to continually monitor the autoplt -- at least one pilot, and avoid complacency during cruise flight when things are usually quiet.) P.south.: there was no altitude alert to help us, since the MCP was programmed for the crossing altitude (FL200).
Original NASA ASRS Text
Title: A B737-300 CLBS 400 FT ABOVE ITS ASSIGNED ALT WHEN THE FO'S MISPROGRAMMING OF THE MCP CAUSES THE ALT HOLD TO DISENGAGE.
Narrative: LEVEL CRUISE AT FL280, WE RECEIVED A NEW ALT OF FL200 WITH XING RESTR, AND SPD INCREASE TO 320 KTS WHEN ABLE. AUTOPLT WAS ON. WHILE CAPT PROGRAMMED THE FMC FOR THE XING AND SPD INCREASE, I ELECTED TO MANUALLY SELECT A HIGHER MACH NUMBER IN THE MASTER CTL PANEL WINDOW TO EXPEDITE THE SPD INCREASE TO HELP ACCOMMODATE ATC. IN DOING SO, I INADVERTENTLY CAUSED THE 'ALT HOLD' MODE TO DISENGAGE SINCE A NEW XING ALT HAD BEEN SET IN THE MCP WINDOW (FL200). THIS AUTOPLT AND FMC ARE NEW TO ME, AND WHILE I OBSERVED THE CAPT COMPLETING THE FMC PROGRAMMING, THE ACFT BEGAN A SLOW CLB. I ALLOWED MYSELF TO BE DISTR, FAILED TO MONITOR THE AUTOPLT DURING THIS SHORT PERIOD, AND SUBSEQUENTLY DID NOT CATCH THE ALTDEV. THE CAPT ALERTED ME AND STOPPED THE CLB APPROX 300-400 FT HIGH. THERE WAS NO CONFLICT WITH ANOTHER ACFT, NO TA/RA, NOR WAS THERE A CALL FROM ATC. (I WAS REMINDED HOW TO NEVER RELY ON AUTOMATION, TO CONTINUALLY MONITOR THE AUTOPLT -- AT LEAST ONE PLT, AND AVOID COMPLACENCY DURING CRUISE FLT WHEN THINGS ARE USUALLY QUIET.) P.S.: THERE WAS NO ALT ALERT TO HELP US, SINCE THE MCP WAS PROGRAMMED FOR THE XING ALT (FL200).
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.