Large transport using flight computers overshoot descent altitude.

Attributes
ACN	274265
Time
Date	199406
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : cle
State Reference	OH
Altitude	msl bound lower : 27500 msl bound upper : 28000
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zob
Operator	common carrier : air carrier
Make Model Name	A320
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	descent other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 180 flight time total : 10500 flight time type : 1200
ASRS Report	274265
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : overshoot non adherence : clearance other anomaly other
Independent Detector	other controllera other flight crewa
Resolutory Action	flight crew : became reoriented flight crew : returned to intended course or assigned course other
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Airbus 320 -- autoplt and automatic throttle active, initially cleared from FL310 to FL280, told to 'hurry down.' aircraft captain selected 'open descent' which brings thrust to idle -- speed controled by pitch angle. 1/2 speed brakes used to expedite descent. Aircraft has approximately 3100 FPM rate and starting to level off by 28700 ft when ZOB cleared us on down to FL240, which was quickly selected so aircraft would not capture FL280 which was seconds from happening. Then ZOB reversed himself and told us to maintain FL280. Aircraft is still in descent mode (vertical speed). It descends on down to 27500 ft then finally reverts to climb mode about the time ATC questions our altitude. Aircraft should have been disconnected off autoplt and aggressively leveled off by captain. Instead, he elected to use FCU (flight control unit). The flight computers, not knowing the urgency, tend to do things softly for passenger comfort.

Original NASA ASRS Text

Title: LGT USING FLT COMPUTERS OVERSHOOT DSCNT ALT.

Narrative: AIRBUS 320 -- AUTOPLT AND AUTO THROTTLE ACTIVE, INITIALLY CLRED FROM FL310 TO FL280, TOLD TO 'HURRY DOWN.' ACFT CAPT SELECTED 'OPEN DSCNT' WHICH BRINGS THRUST TO IDLE -- SPD CTLED BY PITCH ANGLE. 1/2 SPD BRAKES USED TO EXPEDITE DSCNT. ACFT HAS APPROX 3100 FPM RATE AND STARTING TO LEVEL OFF BY 28700 FT WHEN ZOB CLRED US ON DOWN TO FL240, WHICH WAS QUICKLY SELECTED SO ACFT WOULD NOT CAPTURE FL280 WHICH WAS SECONDS FROM HAPPENING. THEN ZOB REVERSED HIMSELF AND TOLD US TO MAINTAIN FL280. ACFT IS STILL IN DSCNT MODE (VERT SPD). IT DSNDS ON DOWN TO 27500 FT THEN FINALLY REVERTS TO CLB MODE ABOUT THE TIME ATC QUESTIONS OUR ALT. ACFT SHOULD HAVE BEEN DISCONNECTED OFF AUTOPLT AND AGGRESSIVELY LEVELED OFF BY CAPT. INSTEAD, HE ELECTED TO USE FCU (FLT CTL UNIT). THE FLT COMPUTERS, NOT KNOWING THE URGENCY, TEND TO DO THINGS SOFTLY FOR PAX COMFORT.

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.