B727-200 crew had an altitude deviation in ZDV class a.

Attributes
ACN	519470
Time
Date	200108
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : ddy.vortac
State Reference	SD
Altitude	msl bound lower : 35000 msl bound upper : 35600
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	B727-200
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : flight engineer pilot : instrument pilot : multi engine pilot : private
Experience	flight time last 90 days : 200 flight time total : 11000 flight time type : 15000
ASRS Report	519470
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : far non adherence : published procedure non adherence : company policies non adherence : clearance
Resolutory Action	flight crew : returned to assigned altitude none taken : anomaly accepted
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

At FL350, PF went to trim the aircraft. Disconnected the autoplt, trimmed, and reconnected the autoplt. We were apparently in about a 50-100 FPM climb. Altitude alert went off at 35.5 and we topped out at 35.6K. We did not notice the slight climb. We immediately returned to FL350. We observed no aircraft in our area (conflict) on TCASII. ZDV never said anything to us.

Original NASA ASRS Text

Title: B727-200 CREW HAD AN ALTDEV IN ZDV CLASS A.

Narrative: AT FL350, PF WENT TO TRIM THE ACFT. DISCONNECTED THE AUTOPLT, TRIMMED, AND RECONNECTED THE AUTOPLT. WE WERE APPARENTLY IN ABOUT A 50-100 FPM CLB. ALT ALERT WENT OFF AT 35.5 AND WE TOPPED OUT AT 35.6K. WE DID NOT NOTICE THE SLIGHT CLB. WE IMMEDIATELY RETURNED TO FL350. WE OBSERVED NO ACFT IN OUR AREA (CONFLICT) ON TCASII. ZDV NEVER SAID ANYTHING TO US.

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.