Air carrier medium large transport overshoots altitude in descent.

Attributes
ACN	163538
Time
Date	199011
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : den
State Reference	CO
Altitude	msl bound lower : 16000 msl bound upper : 17000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdv tower : chs
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	descent other
Route In Use	enroute airway : zdv
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 210 flight time total : 20000 flight time type : 2500
ASRS Report	163538
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 240 flight time total : 14000 flight time type : 6000
ASRS Report	163835
Events
Anomaly	altitude deviation : overshoot non adherence : clearance
Independent Detector	other controllera other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Den area altimeter setting per ATIS 29.43. Descending through FL180 resetting altitude, I initially started to crank the setting upward toward 30.00 instead of downward to 29.43. Rate of descent was high due to ATC request to keep speed up for following aircraft. Aircraft descended through 17000' which I noticed on the standby altimeter located just below the electric altimeter. I quickly set in 29.43, the correct setting, and the aircraft responded by returning to 17000'. The lowest altitude I noticed on the altimeter was 16600'. When ATC asked about our altitude, I explained quickly that we had dipped below 17000', but were now level at 17000'. Requests to 'keep speed up' are common on the air carrier medium large transport due to slow cruise descent economy speeds. This results in high rates of descent. Altimeter reset altitude of 18000'. Level off requirement of 17000' results in a very short time for fmcs aircraft to respond to new data inserted, and very little margin for error.

Original NASA ASRS Text

Title: ACR MLG OVERSHOOTS ALT IN DESCENT.

Narrative: DEN AREA ALTIMETER SETTING PER ATIS 29.43. DSNDING THROUGH FL180 RESETTING ALT, I INITIALLY STARTED TO CRANK THE SETTING UPWARD TOWARD 30.00 INSTEAD OF DOWNWARD TO 29.43. RATE OF DSNT WAS HIGH DUE TO ATC REQUEST TO KEEP SPD UP FOR FOLLOWING ACFT. ACFT DSNDED THROUGH 17000' WHICH I NOTICED ON THE STANDBY ALTIMETER LOCATED JUST BELOW THE ELECTRIC ALTIMETER. I QUICKLY SET IN 29.43, THE CORRECT SETTING, AND THE ACFT RESPONDED BY RETURNING TO 17000'. THE LOWEST ALT I NOTICED ON THE ALTIMETER WAS 16600'. WHEN ATC ASKED ABOUT OUR ALT, I EXPLAINED QUICKLY THAT WE HAD DIPPED BELOW 17000', BUT WERE NOW LEVEL AT 17000'. REQUESTS TO 'KEEP SPD UP' ARE COMMON ON THE ACR MLG DUE TO SLOW CRUISE DSNT ECONOMY SPDS. THIS RESULTS IN HIGH RATES OF DSNT. ALTIMETER RESET ALT OF 18000'. LEVEL OFF REQUIREMENT OF 17000' RESULTS IN A VERY SHORT TIME FOR FMCS ACFT TO RESPOND TO NEW DATA INSERTED, AND VERY LITTLE MARGIN FOR ERROR.

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.