MD88 first officer overshot descent altitude due to autoplt not capturing set altitude.

Attributes
ACN	543793
Time
Date	200203
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : atl.airport
State Reference	GA
Altitude	msl bound lower : 10800 msl bound upper : 11000
Environment
Flight Conditions	Mixed
Light	Night
Aircraft 1
Controlling Facilities	tracon : atl.tracon
Operator	common carrier : air carrier
Make Model Name	MD-88
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : cfi pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 80 flight time total : 7100 flight time type : 815
ASRS Report	543793
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : overshoot non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : altimeter other controllera other flight crewa
Resolutory Action	flight crew : returned to assigned altitude flight crew : overrode automation
Supplementary
Problem Areas	Flight Crew Human Performance Aircraft
Primary Problem	Aircraft

Narrative:

Slat extension, descending, turning and slowing. The FMS in the MD88 has trouble accomplishing all 3 functions at the same time. I learned this in my IOE 800 hours back. I was watching as the airspeed was slowing to 210 IAS, the airplane banked at 25-27 degrees and was leveling at 11000 ft regardless. I was still caught and the airplane descended through the assigned altitude by at least 200 ft. I corrected immediately with pitch (autoplt still engaged) followed by power and pitch with autoplt disengaged. The only mention from the controller was to maintain assigned altitude. This is the first occurrence of this happening to me. Because it's an FMS/autoplt problem which is inherent to this airplane, pilots in the situation above must think ahead to the possible consequences when performing this maneuver and react quicker as deviation becomes evident.

Original NASA ASRS Text

Title: MD88 FO OVERSHOT DSCNT ALT DUE TO AUTOPLT NOT CAPTURING SET ALT.

Narrative: SLAT EXTENSION, DSNDING, TURNING AND SLOWING. THE FMS IN THE MD88 HAS TROUBLE ACCOMPLISHING ALL 3 FUNCTIONS AT THE SAME TIME. I LEARNED THIS IN MY IOE 800 HRS BACK. I WAS WATCHING AS THE AIRSPD WAS SLOWING TO 210 IAS, THE AIRPLANE BANKED AT 25-27 DEGS AND WAS LEVELING AT 11000 FT REGARDLESS. I WAS STILL CAUGHT AND THE AIRPLANE DSNDED THROUGH THE ASSIGNED ALT BY AT LEAST 200 FT. I CORRECTED IMMEDIATELY WITH PITCH (AUTOPLT STILL ENGAGED) FOLLOWED BY PWR AND PITCH WITH AUTOPLT DISENGAGED. THE ONLY MENTION FROM THE CTLR WAS TO MAINTAIN ASSIGNED ALT. THIS IS THE FIRST OCCURRENCE OF THIS HAPPENING TO ME. BECAUSE IT'S AN FMS/AUTOPLT PROB WHICH IS INHERENT TO THIS AIRPLANE, PLTS IN THE SIT ABOVE MUST THINK AHEAD TO THE POSSIBLE CONSEQUENCES WHEN PERFORMING THIS MANEUVER AND REACT QUICKER AS DEV BECOMES EVIDENT.

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.