Excursion from assigned altitude.

Attributes
ACN	462350
Time
Date	200002
Day	Mon
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : zdv.artcc
State Reference	CO
Altitude	msl bound lower : 28000 msl bound upper : 28500
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zdv.artcc
Operator	common carrier : air carrier
Make Model Name	B737-300
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	descent : intermediate altitude
Route In Use	enroute airway : j24.airway
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 80 flight time total : 6986 flight time type : 319
ASRS Report	462350
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial pilot : multi engine
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : returned to assigned altitude none taken : insufficient time
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

ZDV gave us a descent from FL350 to FL280. The copilot was flying and chose flight level change. Descent rate was initially 2500-3000 FPM. At FL285 the aircraft began to slow rate of descent to 300-500 FPM rate of descent. FL250 was acquired by the flight directors and the autoplt initially. Moments later the aircraft began a climb, with vertical speed accelerating through 1000 FPM, flying away from both the captured altitude and flight directors. Copilot disconnected autoplt at approximately 28250 ft with round-out at 28500 ft. Returned to FL280. The whole evolution took approximately 1 1/2 mins.

Original NASA ASRS Text

Title: EXCURSION FROM ASSIGNED ALT.

Narrative: ZDV GAVE US A DSCNT FROM FL350 TO FL280. THE COPLT WAS FLYING AND CHOSE FLT LEVEL CHANGE. DSCNT RATE WAS INITIALLY 2500-3000 FPM. AT FL285 THE ACFT BEGAN TO SLOW RATE OF DSCNT TO 300-500 FPM RATE OF DSCNT. FL250 WAS ACQUIRED BY THE FLT DIRECTORS AND THE AUTOPLT INITIALLY. MOMENTS LATER THE ACFT BEGAN A CLB, WITH VERT SPD ACCELERATING THROUGH 1000 FPM, FLYING AWAY FROM BOTH THE CAPTURED ALT AND FLT DIRECTORS. COPLT DISCONNECTED AUTOPLT AT APPROX 28250 FT WITH ROUND-OUT AT 28500 FT. RETURNED TO FL280. THE WHOLE EVOLUTION TOOK APPROX 1 1/2 MINS.

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.