An MD80 overshoots its assigned altitude during climb. Crew cites an autoplt malfunction. TTT-tx.

Attributes
ACN	452040
Time
Date	199910
Day	Fri
Local Time Of Day	1801 To 2400
Place
State Reference	TX
Altitude	msl bound lower : 27000 msl bound upper : 27500
Environment
Flight Conditions	VMC
Light	Night
Aircraft 1
Controlling Facilities	artcc : zhu.artcc
Operator	common carrier : air carrier
Make Model Name	MD-80 Series (DC-9-80) Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	other vortac
Flight Phase	climbout : vacating altitude cruise : level
Route In Use	departure sid : jpool8
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : flight engineer pilot : instrument pilot : multi engine pilot : atp pilot : cfi pilot : commercial
Experience	flight time last 90 days : 240 flight time total : 8700 flight time type : 750
ASRS Report	452040
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : overshoot non adherence : clearance
Independent Detector	aircraft equipment : altitude alert
Resolutory Action	flight crew : returned to assigned altitude flight crew : overrode automation
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

Clearance to FL270. While climbing through FL260 center had us slow to 280 KIAS. I selected speed select on flight guidance and slowed rate of climb from 2000 FPM to 1000 FPM. Our standard altitude callout, FL260 for FL270 was done. The altitude alert went off at FL273-FL274. The autoplt did not capture even though it was armed. I disconnected autoplt and flew back to FL270. Total deviation approximately 500 ft by the time the descent began. There was no traffic conflict. This was only second leg of a trip with afternoon check-in. However, I had a poor night's sleep and even took a 1/2 hour nap before work but still was not feeling rested. Had a caffinated beverage prior to first leg and tea second but still felt slightly out of sorts. I'll try oxygen in future and let my partner know so he can be extra diligent to any possible mistakes -- instead of normal alertness.

Original NASA ASRS Text

Title: AN MD80 OVERSHOOTS ITS ASSIGNED ALT DURING CLB. CREW CITES AN AUTOPLT MALFUNCTION. TTT-TX.

Narrative: CLRNC TO FL270. WHILE CLBING THROUGH FL260 CTR HAD US SLOW TO 280 KIAS. I SELECTED SPD SELECT ON FLT GUIDANCE AND SLOWED RATE OF CLB FROM 2000 FPM TO 1000 FPM. OUR STANDARD ALT CALLOUT, FL260 FOR FL270 WAS DONE. THE ALT ALERT WENT OFF AT FL273-FL274. THE AUTOPLT DID NOT CAPTURE EVEN THOUGH IT WAS ARMED. I DISCONNECTED AUTOPLT AND FLEW BACK TO FL270. TOTAL DEV APPROX 500 FT BY THE TIME THE DSCNT BEGAN. THERE WAS NO TFC CONFLICT. THIS WAS ONLY SECOND LEG OF A TRIP WITH AFTERNOON CHK-IN. HOWEVER, I HAD A POOR NIGHT'S SLEEP AND EVEN TOOK A 1/2 HR NAP BEFORE WORK BUT STILL WAS NOT FEELING RESTED. HAD A CAFFINATED BEVERAGE PRIOR TO FIRST LEG AND TEA SECOND BUT STILL FELT SLIGHTLY OUT OF SORTS. I'LL TRY OXYGEN IN FUTURE AND LET MY PARTNER KNOW SO HE CAN BE EXTRA DILIGENT TO ANY POSSIBLE MISTAKES -- INSTEAD OF NORMAL ALERTNESS.

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.