<< >> NASA ASRS Report 478613, July 2000

A cpr flight crew flying a giv at FL430 near grb fails to maintain their assigned altitude after the autoplt became inadvertently disengaged.

Attributes
ACN	478613
Time
Date	200007
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : zmp.artcc
State Reference	MN
Altitude	msl bound lower : 43000 msl bound upper : 43400
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zmp.artcc tower : den.tower
Operator	general aviation : corporate
Make Model Name	Gulfstream IV
Operating Under FAR Part	Part 91
Navigation In Use	other
Flight Phase	cruise : level
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Qualification	pilot : multi engine pilot : atp
Experience	flight time last 90 days : 70 flight time total : 16000 flight time type : 450
ASRS Report	478613
Person 2
Affiliation	company : corporate
Function	flight crew : first officer
Qualification	pilot : multi engine pilot : instrument pilot : commercial
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : far non adherence : clearance
Independent Detector	other flight crewa
Resolutory Action	flight crew : regained aircraft control flight crew : returned to assigned altitude
Supplementary
Problem Areas	Flight Crew Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Flight from blm to yxd, copilot needed to go to toilet. Oxygen mask was on. He got out of seat and was standing behind cockpit entrance. Autoplt disc alert sounded. Aircraft began climbing. I re-engaged autoplt. Aircraft continued climbing. Disc autoplt trimmed nose down, re-engaged autoplt and flight level change at FL431. Aircraft deviated to FL434. No traffic near us horizontally or vertically. On ground at yxd, we performed automatic flight guidance computer system (afgcs) check. Flight fault summary showed no reason for autoplt disc. No controls were touched when other pilot left his seat. Field of vision much narrower with oxygen mask.

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Original NASA ASRS Text

Title: A CPR FLC FLYING A GIV AT FL430 NEAR GRB FAILS TO MAINTAIN THEIR ASSIGNED ALT AFTER THE AUTOPLT BECAME INADVERTENTLY DISENGAGED.

Narrative: FLT FROM BLM TO YXD, COPLT NEEDED TO GO TO TOILET. OXYGEN MASK WAS ON. HE GOT OUT OF SEAT AND WAS STANDING BEHIND COCKPIT ENTRANCE. AUTOPLT DISC ALERT SOUNDED. ACFT BEGAN CLBING. I RE-ENGAGED AUTOPLT. ACFT CONTINUED CLBING. DISC AUTOPLT TRIMMED NOSE DOWN, RE-ENGAGED AUTOPLT AND FLT LEVEL CHANGE AT FL431. ACFT DEVIATED TO FL434. NO TFC NEAR US HORIZLY OR VERTLY. ON GND AT YXD, WE PERFORMED AUTO FLT GUIDANCE COMPUTER SYS (AFGCS) CHK. FLT FAULT SUMMARY SHOWED NO REASON FOR AUTOPLT DISC. NO CTLS WERE TOUCHED WHEN OTHER PLT LEFT HIS SEAT. FIELD OF VISION MUCH NARROWER WITH OXYGEN MASK.

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.