Aircraft pitches up abruptly as flight crew tries to overcome an autoplt problem.

Attributes
ACN	242954
Time
Date	199305
Day	Sun
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : phl
State Reference	PA
Altitude	msl bound lower : 15000 msl bound upper : 15000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zdc
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other descent other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : atp pilot : commercial
Experience	flight time last 90 days : 75 flight time total : 20000 flight time type : 1000
ASRS Report	242954
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : overshoot
Independent Detector	other other : unspecified cockpit
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 other

Narrative:

Descending to 13000 ft with the copilot flying using a manual autoplt. A manual turn wheel controls the rate of descent. The aircraft was doing 300 KTS and approximately 2000 FPM descent. Upon reaching 15000 ft the use of the control wheel didn't arrest the descent. I grabbed the controls. The autoplt pulsed as I grabbed the controls. Either one of us then hit the disconnect buttons or the autoplt disconnected by itself causing the aircraft to abruptly pitch up and start climbing rapidly. The abrupt pitch up caused 2 flight attendants to fall to the floor. All passenger were seated and no one was hurt. We wrote the autoplt up and maintenance thought the problem was a too sensitive elevator servo. The thing I really learned the hard way was if you have an autoplt problem, grab the controls lightly and disconnect the autoplt.

Original NASA ASRS Text

Title: ACFT PITCHES UP ABRUPTLY AS FLC TRIES TO OVERCOME AN AUTOPLT PROB.

Narrative: DSNDING TO 13000 FT WITH THE COPLT FLYING USING A MANUAL AUTOPLT. A MANUAL TURN WHEEL CTLS THE RATE OF DSCNT. THE ACFT WAS DOING 300 KTS AND APPROX 2000 FPM DSCNT. UPON REACHING 15000 FT THE USE OF THE CTL WHEEL DIDN'T ARREST THE DSCNT. I GRABBED THE CTLS. THE AUTOPLT PULSED AS I GRABBED THE CTLS. EITHER ONE OF US THEN HIT THE DISCONNECT BUTTONS OR THE AUTOPLT DISCONNECTED BY ITSELF CAUSING THE ACFT TO ABRUPTLY PITCH UP AND START CLBING RAPIDLY. THE ABRUPT PITCH UP CAUSED 2 FLT ATTENDANTS TO FALL TO THE FLOOR. ALL PAX WERE SEATED AND NO ONE WAS HURT. WE WROTE THE AUTOPLT UP AND MAINT THOUGHT THE PROB WAS A TOO SENSITIVE ELEVATOR SERVO. THE THING I REALLY LEARNED THE HARD WAY WAS IF YOU HAVE AN AUTOPLT PROB, GRAB THE CTLS LIGHTLY AND DISCONNECT THE AUTOPLT.

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.