MD80 flight crew descends below reclred altitude.

Attributes
ACN	439480
Time
Date	199906
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : stl.airport
State Reference	MO
Altitude	msl bound lower : 21600 msl bound upper : 22000
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zkc.artcc tower : iad.tower
Operator	common carrier : air carrier
Make Model Name	MD-83
Operating Under FAR Part	Part 121
Navigation In Use	other
Flight Phase	cruise : enroute altitude change
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zkc.artcc
Make Model Name	Twin Beech 18
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : commercial pilot : atp pilot : multi engine
Experience	flight time last 90 days : 98 flight time total : 9000 flight time type : 98
ASRS Report	439480
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : cfi pilot : flight engineer pilot : instrument pilot : multi engine pilot : atp
Experience	flight time last 90 days : 210 flight time total : 9000 flight time type : 1500
ASRS Report	439483
Events
Anomaly	altitude deviation : overshoot conflict : airborne less severe non adherence : clearance non adherence : required legal separation
Independent Detector	atc equipment other atc equipment : radar other controllera other flight crewa other flight crewb
Resolutory Action	controller : issued advisory flight crew : returned to original clearance
Supplementary
Problem Areas	Flight Crew Human Performance ATC Human Performance
Primary Problem	ATC Human Performance
Air Traffic Incident	Pilot Deviation Operational Error

Narrative:

This event is in reference to a flight operating from bos to stl. On descent into stl I was given clearance to descend to 11000 ft. The descent rate was about 2500 FPM. At about FL230 the controller amended clearance to level at FL220. I leveled the aircraft off as rapidly and smoothly as possible, as not to cause injury to crew and passenger. The aircraft descended to FL216. The controller mentioned a conflict with a twin aircraft that was at FL210. I did not visually see this aircraft. I did see it on TCASII. I believe the reason for this incident was due to the controller not giving the clearance to level at FL220 in a timely manner.

Original NASA ASRS Text

Title: MD80 FLC DSNDS BELOW RECLRED ALT.

Narrative: THIS EVENT IS IN REF TO A FLT OPERATING FROM BOS TO STL. ON DSCNT INTO STL I WAS GIVEN CLRNC TO DSND TO 11000 FT. THE DSCNT RATE WAS ABOUT 2500 FPM. AT ABOUT FL230 THE CTLR AMENDED CLRNC TO LEVEL AT FL220. I LEVELED THE ACFT OFF AS RAPIDLY AND SMOOTHLY AS POSSIBLE, AS NOT TO CAUSE INJURY TO CREW AND PAX. THE ACFT DSNDED TO FL216. THE CTLR MENTIONED A CONFLICT WITH A TWIN ACFT THAT WAS AT FL210. I DID NOT VISUALLY SEE THIS ACFT. I DID SEE IT ON TCASII. I BELIEVE THE REASON FOR THIS INCIDENT WAS DUE TO THE CTLR NOT GIVING THE CLRNC TO LEVEL AT FL220 IN A TIMELY MANNER.

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.