<< >> NASA ASRS Report 580298, April 2003

Flight crew of C560 had to override autoflt system when the aircraft diverted from track. During recovery, altitude deviated 300 ft from assigned.

Attributes
ACN	580298
Time
Date	200304
Day	Tue
Local Time Of Day	1201 To 1800
Place
Locale Reference	intersection : crays
State Reference	TX
Altitude	msl single value : 13000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : sat.tracon
Operator	general aviation : personal
Make Model Name	Citation V
Operating Under FAR Part	Part 91
Navigation In Use	other
Flight Phase	descent : intermediate altitude
Route In Use	arrival star : marcs 7
Flight Plan	IFR
Person 1
Affiliation	other
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time total : 3750 flight time type : 750
ASRS Report	580298
Person 2
Affiliation	other
Function	flight crew : first officer
Qualification	pilot : cfi pilot : atp
Experience	flight time last 90 days : 50 flight time total : 3000 flight time type : 380
ASRS Report	580478
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : far non adherence : clearance other spatial deviation
Independent Detector	atc equipment other atc equipment : radar other controllera other flight crewa
Resolutory Action	controller : issued new clearance flight crew : overrode automation flight crew : returned to assigned altitude flight crew : returned to intended or assigned course
Supplementary
Problem Areas	Aircraft Flight Crew Human Performance
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

When approaching crays intersection on the marcs 7 arrival into sat, the autoplt (while utilizing FMS navigation guidance) commanded a turn to the left rather than proceeding to the next fix on the arrival which would have been marcs intersection. Seeing that the aircraft was turning away from the correct course, I instructed the first officer, who was PF, to select heading mode and make an immediate course correction. The first officer then disconnected the autoplt and the aircraft immediately lost 300 ft of altitude and turned more rapidly to the left. I briefly assumed control of the aircraft and made an immediate altitude correction and began a turn back toward the correct course. I returned the controls to the first officer, the autoplt was re-engaged. ATC stated 'you are south of course, fly heading 290 degrees.' heading 290 degrees was selected and the aircraft was re-established on the proper course for the arrival. There was no further communication from ATC regarding the matter. It appears the aircraft was attempting to enter a holding pattern at crays for reasons unknown. This situation could have been prevented by assuming control of the aircraft sooner after making repeated statements to the PF to make a course correction. I still do not know why the FMS would command the autoplt to enter holding when no holding pattern had been programmed.

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Original NASA ASRS Text

Title: FLT CREW OF C560 HAD TO OVERRIDE AUTOFLT SYS WHEN THE ACFT DIVERTED FROM TRACK. DURING RECOVERY, ALT DEVIATED 300 FT FROM ASSIGNED.

Narrative: WHEN APCHING CRAYS INTXN ON THE MARCS 7 ARR INTO SAT, THE AUTOPLT (WHILE UTILIZING FMS NAV GUIDANCE) COMMANDED A TURN TO THE L RATHER THAN PROCEEDING TO THE NEXT FIX ON THE ARR WHICH WOULD HAVE BEEN MARCS INTXN. SEEING THAT THE ACFT WAS TURNING AWAY FROM THE CORRECT COURSE, I INSTRUCTED THE FO, WHO WAS PF, TO SELECT HDG MODE AND MAKE AN IMMEDIATE COURSE CORRECTION. THE FO THEN DISCONNECTED THE AUTOPLT AND THE ACFT IMMEDIATELY LOST 300 FT OF ALT AND TURNED MORE RAPIDLY TO THE L. I BRIEFLY ASSUMED CTL OF THE ACFT AND MADE AN IMMEDIATE ALT CORRECTION AND BEGAN A TURN BACK TOWARD THE CORRECT COURSE. I RETURNED THE CTLS TO THE FO, THE AUTOPLT WAS RE-ENGAGED. ATC STATED 'YOU ARE S OF COURSE, FLY HDG 290 DEGS.' HDG 290 DEGS WAS SELECTED AND THE ACFT WAS RE-ESTABLISHED ON THE PROPER COURSE FOR THE ARR. THERE WAS NO FURTHER COM FROM ATC REGARDING THE MATTER. IT APPEARS THE ACFT WAS ATTEMPTING TO ENTER A HOLDING PATTERN AT CRAYS FOR REASONS UNKNOWN. THIS SIT COULD HAVE BEEN PREVENTED BY ASSUMING CTL OF THE ACFT SOONER AFTER MAKING REPEATED STATEMENTS TO THE PF TO MAKE A COURSE CORRECTION. I STILL DO NOT KNOW WHY THE FMS WOULD COMMAND THE AUTOPLT TO ENTER HOLDING WHEN NO HOLDING PATTERN HAD BEEN PROGRAMMED.

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.