Flight crew of an light transport busted their altitude assignment. Clearance pilot discretion.

Attributes
ACN	296080
Time
Date	199502
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : cap
State Reference	IL
Altitude	msl bound lower : 14500 msl bound upper : 15500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : stt
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	cruise other descent other
Route In Use	enroute airway : v9
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : flight engineer pilot : instrument pilot : cfi
Experience	flight time last 90 days : 150 flight time total : 3300 flight time type : 150
ASRS Report	296080
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 : far non adherence : clearance
Independent Detector	atc equipment other atc equipment : unspecified other controllera
Resolutory Action	flight crew : returned to intended course or assigned course other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

While cruising at 15000 ft we were cleared to descend at pilot's discretion to 13000 ft. I selected 13000 ft in the altitude preselector and began to descend on the autoplt. I then remembered I had not yet recorded the engine trend data which needs to be done in cruise at an altitude as close to 15000 ft as possible. I set the autoplt to climb back to 15000 ft but I forgot to reset the altitude preselector. While I was opening the engine logbook the aircraft climbed through 15000 ft by about 500 ft. ATC was the first to alert us and we were able to descend below 15000 ft within a few seconds. In the past I usually transferred control of the aircraft to the other pilot while filling out the log but for some reason I failed to do so in this case. I also placed too much trust in the autoplt to accomplish the leveloff at 15000 ft for me while my head was down.

Original NASA ASRS Text

Title: FLC OF AN LTT BUSTED THEIR ALT ASSIGNMENT. CLRNC PLT DISCRETION.

Narrative: WHILE CRUISING AT 15000 FT WE WERE CLRED TO DSND AT PLT'S DISCRETION TO 13000 FT. I SELECTED 13000 FT IN THE ALT PRESELECTOR AND BEGAN TO DSND ON THE AUTOPLT. I THEN REMEMBERED I HAD NOT YET RECORDED THE ENG TREND DATA WHICH NEEDS TO BE DONE IN CRUISE AT AN ALT AS CLOSE TO 15000 FT AS POSSIBLE. I SET THE AUTOPLT TO CLB BACK TO 15000 FT BUT I FORGOT TO RESET THE ALT PRESELECTOR. WHILE I WAS OPENING THE ENG LOGBOOK THE ACFT CLBED THROUGH 15000 FT BY ABOUT 500 FT. ATC WAS THE FIRST TO ALERT US AND WE WERE ABLE TO DSND BELOW 15000 FT WITHIN A FEW SECONDS. IN THE PAST I USUALLY TRANSFERRED CTL OF THE ACFT TO THE OTHER PLT WHILE FILLING OUT THE LOG BUT FOR SOME REASON I FAILED TO DO SO IN THIS CASE. I ALSO PLACED TOO MUCH TRUST IN THE AUTOPLT TO ACCOMPLISH THE LEVELOFF AT 15000 FT FOR ME WHILE MY HEAD WAS DOWN.

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.