An air carrier flight crew temporarily loses control of their aircraft when the autoplt makes an unc...

Attributes
ACN	436400
Time
Date	199905
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	navaid : dqo.vortac
State Reference	DE
Altitude	msl bound lower : 21000 msl bound upper : 21500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zny.artcc
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	other other vortac
Flight Phase	cruise : enroute altitude change cruise : level
Route In Use	arrival star : minks
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : flight engineer pilot : atp
Experience	flight time last 90 days : 200 flight time total : 8000 flight time type : 1000
ASRS Report	436400
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : multi engine pilot : commercial
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly
Independent Detector	other flight crewa
Resolutory Action	flight crew : regained aircraft control flight crew : returned to original clearance flight crew : overrode automation
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

In cruise at FL210, I (captain) put in the FMC a slower speed from 320 KIAS to 220 KIAS per nyc instructions. Previously noted slow FMC speed response due to sluggish autothrottle response. Aircraft slowing gradually. Immediately afterward first officer put in descent and speed increase to increase speed to 250 KIAS and descend to cross somto at 13000 ft. This was entered and executed. Very shortly afterwards captain, first officer and jump seater all noticed aircraft climbing. I saw the vertical speed window open (it should not have been -- and it had been closed) with a positive value in it. I first tried to dial in a descent via the vertical speed window but the aircraft did not respond. I then hit 'level change' but there was no response. I finally disconnected the autoplt and autothrottles and descended back to FL210. We got up to FL215 in the excursion. No aircraft were near by and ATC said nothing about the event. All system re-engaged normally but speed/autothrottle response remained sluggish.

Original NASA ASRS Text

Title: AN ACR FLC TEMPORARILY LOSES CTL OF THEIR ACFT WHEN THE AUTOPLT MAKES AN UNCOMMANDED CLB.

Narrative: IN CRUISE AT FL210, I (CAPT) PUT IN THE FMC A SLOWER SPD FROM 320 KIAS TO 220 KIAS PER NYC INSTRUCTIONS. PREVIOUSLY NOTED SLOW FMC SPD RESPONSE DUE TO SLUGGISH AUTOTHROTTLE RESPONSE. ACFT SLOWING GRADUALLY. IMMEDIATELY AFTERWARD FO PUT IN DSCNT AND SPD INCREASE TO INCREASE SPD TO 250 KIAS AND DSND TO CROSS SOMTO AT 13000 FT. THIS WAS ENTERED AND EXECUTED. VERY SHORTLY AFTERWARDS CAPT, FO AND JUMP SEATER ALL NOTICED ACFT CLBING. I SAW THE VERT SPD WINDOW OPEN (IT SHOULD NOT HAVE BEEN -- AND IT HAD BEEN CLOSED) WITH A POSITIVE VALUE IN IT. I FIRST TRIED TO DIAL IN A DSCNT VIA THE VERT SPD WINDOW BUT THE ACFT DID NOT RESPOND. I THEN HIT 'LEVEL CHANGE' BUT THERE WAS NO RESPONSE. I FINALLY DISCONNECTED THE AUTOPLT AND AUTOTHROTTLES AND DSNDED BACK TO FL210. WE GOT UP TO FL215 IN THE EXCURSION. NO ACFT WERE NEAR BY AND ATC SAID NOTHING ABOUT THE EVENT. ALL SYS RE-ENGAGED NORMALLY BUT SPD/AUTOTHROTTLE RESPONSE REMAINED SLUGGISH.

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.

An air carrier flight crew temporarily loses control of their aircraft when the autoplt makes an uncommanded climb.