Narrative:

In level flight, during dfw area departure (texona 6) aircraft climbed from FL260 to FL265 while being hand flown. Greater than expected control input required to stop altitude deviation. Aircraft stopped uncommanded climb at +500 ft and began to descend. Descended through FL260 to FL255. Aircraft was immediately returned to level flight at FL260. No query from ARTCC controller. Prior to altitude deviation, controller assigned radar vector (360 degrees) and told crew to expect climb to FL280. Deviation was not a result of confusion by ATC. However, crew noticed a 900 pounds fuel imbal prior to deviation. 900 pounds is unusual for phase of flight that soon after takeoff. Possible that high workload and unusual situation contributed to altitude deviation as aircraft was being flown by hand. In future, I will not allow such a distraction to compromise aircraft control. More use of autoplt will be made.

Google
 

Original NASA ASRS Text

Title: DISTR FLC ERRONEOUSLY DEVIATED PLUS AND MINUS 500 FT FROM ASSIGNED FLT LVL AT LEVELOFF ON CLB FROM DFW, TX.

Narrative: IN LEVEL FLT, DURING DFW AREA DEP (TEXONA 6) ACFT CLBED FROM FL260 TO FL265 WHILE BEING HAND FLOWN. GREATER THAN EXPECTED CTL INPUT REQUIRED TO STOP ALTDEV. ACFT STOPPED UNCOMMANDED CLB AT +500 FT AND BEGAN TO DSND. DSNDED THROUGH FL260 TO FL255. ACFT WAS IMMEDIATELY RETURNED TO LEVEL FLT AT FL260. NO QUERY FROM ARTCC CTLR. PRIOR TO ALTDEV, CTLR ASSIGNED RADAR VECTOR (360 DEGS) AND TOLD CREW TO EXPECT CLB TO FL280. DEV WAS NOT A RESULT OF CONFUSION BY ATC. HOWEVER, CREW NOTICED A 900 LBS FUEL IMBAL PRIOR TO DEV. 900 LBS IS UNUSUAL FOR PHASE OF FLT THAT SOON AFTER TKOF. POSSIBLE THAT HIGH WORKLOAD AND UNUSUAL SIT CONTRIBUTED TO ALTDEV AS ACFT WAS BEING FLOWN BY HAND. IN FUTURE, I WILL NOT ALLOW SUCH A DISTR TO COMPROMISE ACFT CTL. MORE USE OF AUTOPLT WILL BE MADE.

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.