Altitude overshoot in climb for 'glass cockpit' medium large transport that often has this problem.

Attributes
ACN	149723
Time
Date	199006
Day	Tue
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : atl
State Reference	GA
Altitude	msl bound lower : 10000 msl bound upper : 10400
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : atl
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	climbout : intermediate altitude
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 : 7000 flight time type : 130
ASRS Report	149723
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 180 flight time total : 9700 flight time type : 1000
ASRS Report	149620
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : overshoot non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	flight crew : returned to intended course or assigned course flight crew : overcame equipment problem
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

During a departure from atl, while passing through 8300' using VNAV, I engaged autoplt for level off at 10000' as assigned. We were given a turn to 270 degree and as aircraft initiated turn FMS VNAV pitched aircraft up to 15 degree anu. Rate of climb accelerated to 4500-5000 FPM. Although FMA did annunciate 'VNAV climb, VNAV cap' then (captain observed 'VNAV climb') with no attempt to level off at 10000'. I disconnected autoplt at 9400' and returned to 10000' after reaching/topping out at 10400 MSL. ATC then gave a climb ot 14000'. When ATC was questioned, they said we had showed level at 10000' and were cleared to 14000'. No conflict was observed with other traffic in area. I believe the FMS/DFGS interface in the type a medium large transport requires very close watching by the flight crew. The 'black boxes' do not always do what they were commanded to accomplish. Supplemental information from acn 149620. Unsure of cause, FMS appeared 'confused' by second punch of VNAV button as this seemed to occur about the same time as 'altitude cap' was annunciated on mode display panel. Unsure of what the FMS was looking at after this; but the autoplt payed no attention to the FMS annunciations, only maintained 15 degree to 18 degree anu and climb power west/O regard to level commands.

Original NASA ASRS Text

Title: ALT OVERSHOOT IN CLIMB FOR 'GLASS COCKPIT' MLG THAT OFTEN HAS THIS PROBLEM.

Narrative: DURING A DEP FROM ATL, WHILE PASSING THROUGH 8300' USING VNAV, I ENGAGED AUTOPLT FOR LEVEL OFF AT 10000' AS ASSIGNED. WE WERE GIVEN A TURN TO 270 DEG AND AS ACFT INITIATED TURN FMS VNAV PITCHED ACFT UP TO 15 DEG ANU. RATE OF CLB ACCELERATED TO 4500-5000 FPM. ALTHOUGH FMA DID ANNUNCIATE 'VNAV CLB, VNAV CAP' THEN (CAPT OBSERVED 'VNAV CLB') WITH NO ATTEMPT TO LEVEL OFF AT 10000'. I DISCONNECTED AUTOPLT AT 9400' AND RETURNED TO 10000' AFTER REACHING/TOPPING OUT AT 10400 MSL. ATC THEN GAVE A CLB OT 14000'. WHEN ATC WAS QUESTIONED, THEY SAID WE HAD SHOWED LEVEL AT 10000' AND WERE CLRED TO 14000'. NO CONFLICT WAS OBSERVED WITH OTHER TFC IN AREA. I BELIEVE THE FMS/DFGS INTERFACE IN THE TYPE A MLG REQUIRES VERY CLOSE WATCHING BY THE FLT CREW. THE 'BLACK BOXES' DO NOT ALWAYS DO WHAT THEY WERE COMMANDED TO ACCOMPLISH. SUPPLEMENTAL INFO FROM ACN 149620. UNSURE OF CAUSE, FMS APPEARED 'CONFUSED' BY SECOND PUNCH OF VNAV BUTTON AS THIS SEEMED TO OCCUR ABOUT THE SAME TIME AS 'ALT CAP' WAS ANNUNCIATED ON MODE DISPLAY PANEL. UNSURE OF WHAT THE FMS WAS LOOKING AT AFTER THIS; BUT THE AUTOPLT PAYED NO ATTN TO THE FMS ANNUNCIATIONS, ONLY MAINTAINED 15 DEG TO 18 DEG ANU AND CLB PWR W/O REGARD TO LEVEL COMMANDS.

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.