Altitude excursion when pms malfunctioned and pilot slow to respond.

Attributes
ACN	166568
Time
Date	199012
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : iiw
State Reference	KY
Altitude	msl bound lower : 33000 msl bound upper : 33500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zid
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 240 flight time total : 16500 flight time type : 1000
ASRS Report	166568
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : instrument pilot : commercial
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : returned to intended course or assigned course
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Level flight at FL330, aircraft on pms cruise. Had been level at least 1 hour. I was checking a chart and heard altitude warning. I looked up and saw we were 300' high and climbing. The first officer, who was flying, started to fiddle with the autoplt. He did not take hold of the yoke and fly the aircraft. We were by then at 33500'. I then pushed on the yoke and said, 'descend to 33000'.' I held the yoke forward until we were at 33200' and told the first officer, 'you've got it.' the aircraft immediately started to climb again and he again played with the autoplt rather than take positive control of the aircraft. At that time I disconnected the autoplt and leveled the aircraft at 33000'. Then reengaged the autoplt west/O the pms and everything was fine. This same scenario has happened at least 4 other times with a first officer flying in cruise after a period of time with the pms engaged, all within the last yr. Maintenance can find nothing wrong with the system. I see 2 problems: 1) the black box cannot be trusted, which is something most recent new hires are not aware of. Most times this has happened the first officer has been ex-military with 2-3 yrs with our company. 2) the modern pilot, it seems, is unable or reluctant to question the computer and to disengage it. It seems these pilots were taught that computers are right and better than themselves, even when other hard evidence suggests otherwise. Callback conversation with reporter revealed the following: pms is programmed to maintain altitude by beginning a climb or descent for a short period, before the autothrottles begin to activate. Feels this leads to altitude deviation beyond the limits, but in the case reported is sure there was a malfunction in the autoplt system. The company is presently upgrading all altitude select computers so it is no longer necessary to arm the system. Altitude selected will be captured. Reference to the report says many military trained pilots will try to correct the automatics first vs taking the aircraft manually.

Original NASA ASRS Text

Title: ALT EXCURSION WHEN PMS MALFUNCTIONED AND PLT SLOW TO RESPOND.

Narrative: LEVEL FLT AT FL330, ACFT ON PMS CRUISE. HAD BEEN LEVEL AT LEAST 1 HR. I WAS CHKING A CHART AND HEARD ALT WARNING. I LOOKED UP AND SAW WE WERE 300' HIGH AND CLBING. THE F/O, WHO WAS FLYING, STARTED TO FIDDLE WITH THE AUTOPLT. HE DID NOT TAKE HOLD OF THE YOKE AND FLY THE ACFT. WE WERE BY THEN AT 33500'. I THEN PUSHED ON THE YOKE AND SAID, 'DSND TO 33000'.' I HELD THE YOKE FORWARD UNTIL WE WERE AT 33200' AND TOLD THE F/O, 'YOU'VE GOT IT.' THE ACFT IMMEDIATELY STARTED TO CLB AGAIN AND HE AGAIN PLAYED WITH THE AUTOPLT RATHER THAN TAKE POSITIVE CTL OF THE ACFT. AT THAT TIME I DISCONNECTED THE AUTOPLT AND LEVELED THE ACFT AT 33000'. THEN REENGAGED THE AUTOPLT W/O THE PMS AND EVERYTHING WAS FINE. THIS SAME SCENARIO HAS HAPPENED AT LEAST 4 OTHER TIMES WITH A F/O FLYING IN CRUISE AFTER A PERIOD OF TIME WITH THE PMS ENGAGED, ALL WITHIN THE LAST YR. MAINT CAN FIND NOTHING WRONG WITH THE SYS. I SEE 2 PROBS: 1) THE BLACK BOX CANNOT BE TRUSTED, WHICH IS SOMETHING MOST RECENT NEW HIRES ARE NOT AWARE OF. MOST TIMES THIS HAS HAPPENED THE F/O HAS BEEN EX-MIL WITH 2-3 YRS WITH OUR COMPANY. 2) THE MODERN PLT, IT SEEMS, IS UNABLE OR RELUCTANT TO QUESTION THE COMPUTER AND TO DISENGAGE IT. IT SEEMS THESE PLTS WERE TAUGHT THAT COMPUTERS ARE RIGHT AND BETTER THAN THEMSELVES, EVEN WHEN OTHER HARD EVIDENCE SUGGESTS OTHERWISE. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING: PMS IS PROGRAMMED TO MAINTAIN ALT BY BEGINNING A CLB OR DSNT FOR A SHORT PERIOD, BEFORE THE AUTOTHROTTLES BEGIN TO ACTIVATE. FEELS THIS LEADS TO ALT DEVIATION BEYOND THE LIMITS, BUT IN THE CASE RPTED IS SURE THERE WAS A MALFUNCTION IN THE AUTOPLT SYS. THE COMPANY IS PRESENTLY UPGRADING ALL ALT SELECT COMPUTERS SO IT IS NO LONGER NECESSARY TO ARM THE SYS. ALT SELECTED WILL BE CAPTURED. REF TO THE RPT SAYS MANY MIL TRAINED PLTS WILL TRY TO CORRECT THE AUTOMATICS FIRST VS TAKING THE ACFT MANUALLY.

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.