B732 crew, upon leveling at STAR crossing restr, drifted off assigned altitude.

Attributes
ACN	498390
Time
Date	200101
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : dfw.airport
State Reference	TX
Altitude	msl bound lower : 10600 msl bound upper : 11000
Environment
Flight Conditions	IMC
Weather Elements	Rain Turbulence
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : d10.tracon
Operator	common carrier : air carrier
Make Model Name	B737-200
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude
Route In Use	arrival star : cqy.cqy 4
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 : 120 flight time total : 5000 flight time type : 700
ASRS Report	498390
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : atp pilot : commercial pilot : flight engineer
Experience	flight time last 90 days : 180 flight time total : 17000 flight time type : 2500
ASRS Report	498016
Events
Anomaly	altitude deviation : excursion from assigned altitude inflight encounter : turbulence inflight encounter : weather non adherence : clearance other anomaly other
Independent Detector	other controllera
Resolutory Action	flight crew : returned to assigned altitude
Supplementary
Problem Areas	Aircraft Weather Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

At approximately XA30 on jan/xa/01, we were flying the cedar creek 4 arrival to dfw. We were on the cedar creek 309 degree radial and had leveled off at 11000 ft prior to the tacke intersection as cleared by ATC. Shortly after leveling off, ATC called us and stated that we were assigned 11000 ft and he was showing us at 10600 ft. We were in fact at 10600 ft and immediately climbed back to 11000 ft. I consider the primary factor that caused this to be that we were flying an aircraft with a lower level of automation than we are used to in a high workload environment. 90% of the time we fly a model of the B737-200 with the SP177 autoplt (a fairly modern autoplt and MCP, which includes autothrottles and automatic altitude capture). On this flight, we were flying 1 of the 2 aircraft in our fleet with the SP77 autoplt (an older autoplt system, which has no autothrottles or automatic altitude capture function). At the time of the deviation we were busy with the arrival and deviating for WX,. I believe what happened is that as I leveled off at 11000 ft something distraction me from engaging the altitude hold selector. The aircraft stayed in the control wheel steering mode in a slight descent rate. Most of the time, when we fly with the SP177, we do not have to physically engaged altitude hold. It didn't take much for me to be distraction from this task since we were very busy and lacked proficiency and familiarity with the aircraft. Another factor is the fact that we were only afforded 6 hours of sleep the night before. The scheduled layover time was just over 9 hours. Due to our tight turn times and having to change aircraft the night before, we were not able to eat dinner at a normal time during our duty day. As a result, we had to eat dinner after arriving at our hotel. This, combined with the fact that our ride from the airport to the hotel was late picking us up, only left time for about 6 hours of sleep. For me personally, this is a barely adequate amount of sleep, and definitely not optimal.

Original NASA ASRS Text

Title: B732 CREW, UPON LEVELING AT STAR XING RESTR, DRIFTED OFF ASSIGNED ALT.

Narrative: AT APPROX XA30 ON JAN/XA/01, WE WERE FLYING THE CEDAR CREEK 4 ARR TO DFW. WE WERE ON THE CEDAR CREEK 309 DEG RADIAL AND HAD LEVELED OFF AT 11000 FT PRIOR TO THE TACKE INTXN AS CLRED BY ATC. SHORTLY AFTER LEVELING OFF, ATC CALLED US AND STATED THAT WE WERE ASSIGNED 11000 FT AND HE WAS SHOWING US AT 10600 FT. WE WERE IN FACT AT 10600 FT AND IMMEDIATELY CLBED BACK TO 11000 FT. I CONSIDER THE PRIMARY FACTOR THAT CAUSED THIS TO BE THAT WE WERE FLYING AN ACFT WITH A LOWER LEVEL OF AUTOMATION THAN WE ARE USED TO IN A HIGH WORKLOAD ENVIRONMENT. 90% OF THE TIME WE FLY A MODEL OF THE B737-200 WITH THE SP177 AUTOPLT (A FAIRLY MODERN AUTOPLT AND MCP, WHICH INCLUDES AUTOTHROTTLES AND AUTOMATIC ALT CAPTURE). ON THIS FLT, WE WERE FLYING 1 OF THE 2 ACFT IN OUR FLEET WITH THE SP77 AUTOPLT (AN OLDER AUTOPLT SYS, WHICH HAS NO AUTOTHROTTLES OR AUTOMATIC ALT CAPTURE FUNCTION). AT THE TIME OF THE DEV WE WERE BUSY WITH THE ARR AND DEVIATING FOR WX,. I BELIEVE WHAT HAPPENED IS THAT AS I LEVELED OFF AT 11000 FT SOMETHING DISTR ME FROM ENGAGING THE ALT HOLD SELECTOR. THE ACFT STAYED IN THE CTL WHEEL STEERING MODE IN A SLIGHT DSCNT RATE. MOST OF THE TIME, WHEN WE FLY WITH THE SP177, WE DO NOT HAVE TO PHYSICALLY ENGAGED ALT HOLD. IT DIDN'T TAKE MUCH FOR ME TO BE DISTR FROM THIS TASK SINCE WE WERE VERY BUSY AND LACKED PROFICIENCY AND FAMILIARITY WITH THE ACFT. ANOTHER FACTOR IS THE FACT THAT WE WERE ONLY AFFORDED 6 HRS OF SLEEP THE NIGHT BEFORE. THE SCHEDULED LAYOVER TIME WAS JUST OVER 9 HRS. DUE TO OUR TIGHT TURN TIMES AND HAVING TO CHANGE ACFT THE NIGHT BEFORE, WE WERE NOT ABLE TO EAT DINNER AT A NORMAL TIME DURING OUR DUTY DAY. AS A RESULT, WE HAD TO EAT DINNER AFTER ARRIVING AT OUR HOTEL. THIS, COMBINED WITH THE FACT THAT OUR RIDE FROM THE ARPT TO THE HOTEL WAS LATE PICKING US UP, ONLY LEFT TIME FOR ABOUT 6 HRS OF SLEEP. FOR ME PERSONALLY, THIS IS A BARELY ADEQUATE AMOUNT OF SLEEP, AND DEFINITELY NOT OPTIMAL.

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.