Altitude deviation altitude excursion during radar vectoring.

Attributes
ACN	241109
Time
Date	199305
Day	Sat
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : syr
State Reference	NY
Altitude	msl bound lower : 34000 msl bound upper : 35000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zob
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : instrument pilot : commercial pilot : atp
Experience	flight time last 90 days : 200 flight time total : 11000 flight time type : 200
ASRS Report	241109
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly
Independent Detector	other controllera other flight crewa
Resolutory Action	flight crew : overcame equipment problem flight crew : regained aircraft control flight crew : returned to intended course or assigned course
Consequence	faa : reviewed incident with flight crew Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

Medium large transport was level at FL350 close to syr VOR. ATC gave us a 30 degree right turn for spacing into dtw. Halfway through the turn the aircraft started a very rapid 2000 FPM descent with the autoplt on. When the autoplt was disconnected there was a lot of nose down trim which slowed recovery from the rapid descent. 1000 ft was lost. ATC was notified. A normal climb was started back to FL350. Everything seemed normal until a left turn back on course was issued by ATC. Approximately 1/2 through the turn, a descent was started again. This time recovery was made at a 400 ft loss. ATC was notified. Autoplt was not used for turns rest of the flight. Maintenance was notified of problem. ATC said there were no conflicts and requested that we not use the autoplt after the second descent. Rest of the flight was normal.

Original NASA ASRS Text

Title: ALTDEV ALT EXCURSION DURING RADAR VECTORING.

Narrative: MLG WAS LEVEL AT FL350 CLOSE TO SYR VOR. ATC GAVE US A 30 DEG R TURN FOR SPACING INTO DTW. HALFWAY THROUGH THE TURN THE ACFT STARTED A VERY RAPID 2000 FPM DSCNT WITH THE AUTOPLT ON. WHEN THE AUTOPLT WAS DISCONNECTED THERE WAS A LOT OF NOSE DOWN TRIM WHICH SLOWED RECOVERY FROM THE RAPID DSCNT. 1000 FT WAS LOST. ATC WAS NOTIFIED. A NORMAL CLB WAS STARTED BACK TO FL350. EVERYTHING SEEMED NORMAL UNTIL A L TURN BACK ON COURSE WAS ISSUED BY ATC. APPROX 1/2 THROUGH THE TURN, A DSCNT WAS STARTED AGAIN. THIS TIME RECOVERY WAS MADE AT A 400 FT LOSS. ATC WAS NOTIFIED. AUTOPLT WAS NOT USED FOR TURNS REST OF THE FLT. MAINT WAS NOTIFIED OF PROB. ATC SAID THERE WERE NO CONFLICTS AND REQUESTED THAT WE NOT USE THE AUTOPLT AFTER THE SECOND DSCNT. REST OF THE FLT WAS NORMAL.

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.