MD80 crew had altitude overshoot.

Attributes
ACN	437250
Time
Date	199905
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : zse.artcc
State Reference	WA
Altitude	msl bound lower : 23700 msl bound upper : 24000
Environment
Light	Night
Aircraft 1
Controlling Facilities	artcc : zse.artcc tower : stl.tower
Operator	common carrier : air carrier
Make Model Name	MD-80 Super 80
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : multi engine pilot : instrument
ASRS Report	437250
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : overshoot non adherence : clearance
Independent Detector	other flight crewa other flight crewb
Resolutory Action	flight crew : returned to original clearance
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

Altitude deviation. At the request of ATC, we were making our descent into sea at high speed, mach .80, 4500 FPM, in performance mode. As the intermediate leveloff altitude was approached (FL240) the autoplt could not trim fast enough, and the aircraft descended through the altitude by approximately 300 ft. The aircraft was taken off of autoplt to return to altitude. There was significant nose-down trim to be overcome. ATC did not indicate that there was ever a loss of separation. In the future for abnormally high rates of descent I will not depend on performance mode, but will manually reduce the rate about 2000 ft above leveloff.

Original NASA ASRS Text

Title: MD80 CREW HAD ALT OVERSHOOT.

Narrative: ALTDEV. AT THE REQUEST OF ATC, WE WERE MAKING OUR DSCNT INTO SEA AT HIGH SPD, MACH .80, 4500 FPM, IN PERFORMANCE MODE. AS THE INTERMEDIATE LEVELOFF ALT WAS APCHED (FL240) THE AUTOPLT COULD NOT TRIM FAST ENOUGH, AND THE ACFT DSNDED THROUGH THE ALT BY APPROX 300 FT. THE ACFT WAS TAKEN OFF OF AUTOPLT TO RETURN TO ALT. THERE WAS SIGNIFICANT NOSE-DOWN TRIM TO BE OVERCOME. ATC DID NOT INDICATE THAT THERE WAS EVER A LOSS OF SEPARATION. IN THE FUTURE FOR ABNORMALLY HIGH RATES OF DSCNT I WILL NOT DEPEND ON PERFORMANCE MODE, BUT WILL MANUALLY REDUCE THE RATE ABOUT 2000 FT ABOVE LEVELOFF.

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.