FA50 experienced TCASII RA with traffic having difficulty stabilizing altitude at FL220 in ZID airsp...

Attributes
ACN	605377
Time
Date	200401
Day	Fri
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : sdf.airport
State Reference	KY
Altitude	msl bound lower : 21000 msl bound upper : 22000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zid.artcc
Operator	general aviation : corporate
Make Model Name	Falcon 50
Operating Under FAR Part	Part 91
Navigation In Use	other
Flight Phase	descent : intermediate altitude
Route In Use	arrival : on vectors arrival star : darby three
Flight Plan	IFR
Aircraft 2
Controlling Facilities	artcc : zid.artcc
Make Model Name	PA-31T-1 Cheyenne I
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Flight Plan	IFR
Person 1
Affiliation	company : corporate
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 90 flight time total : 11800 flight time type : 400
ASRS Report	605377
Person 2
Affiliation	company : corporate
Function	flight crew : first officer
Events
Anomaly	altitude deviation : excursion from assigned altitude conflict : airborne less severe non adherence : clearance non adherence : required legal separation
Independent Detector	aircraft equipment : tcas other flight crewa
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Miss Distance	horizontal : 500 vertical : 0
Supplementary
Problem Areas	Weather Flight Crew Human Performance Aircraft ATC Human Performance
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	other

Narrative:

On the darby 3 arrival into sdf, ZID needed additional spacing from aircraft in front of us and gave us a command to turn right 030 degree heading, slow to 250 KTS, descend to FL220. First officer and I noticed this would place us on potential collision vector with another aircraft flying at FL210. We noticed this aircraft's TCASII altitude was climbing and descending as if having trouble maintaining altitude. Nearing our leveloff altitude, our TCASII gave an RA warning with climb command greater than 2000 FPM, so we responded. Flight would be climbing through FL230 before RA alert canceled. I called center and talked to controller. He stated 'cheyenne' altitude appeared erratic, and from discussion appears our TCASII equipment operated properly and gave correct command to climb. Flight proceeded with no further incident.

Original NASA ASRS Text

Title: FA50 EXPERIENCED TCASII RA WITH TFC HAVING DIFFICULTY STABILIZING ALT AT FL220 IN ZID AIRSPACE.

Narrative: ON THE DARBY 3 ARR INTO SDF, ZID NEEDED ADDITIONAL SPACING FROM ACFT IN FRONT OF US AND GAVE US A COMMAND TO TURN R 030 DEG HDG, SLOW TO 250 KTS, DSND TO FL220. FO AND I NOTICED THIS WOULD PLACE US ON POTENTIAL COLLISION VECTOR WITH ANOTHER ACFT FLYING AT FL210. WE NOTICED THIS ACFT'S TCASII ALT WAS CLBING AND DSNDING AS IF HAVING TROUBLE MAINTAINING ALT. NEARING OUR LEVELOFF ALT, OUR TCASII GAVE AN RA WARNING WITH CLB COMMAND GREATER THAN 2000 FPM, SO WE RESPONDED. FLT WOULD BE CLBING THROUGH FL230 BEFORE RA ALERT CANCELED. I CALLED CTR AND TALKED TO CTLR. HE STATED 'CHEYENNE' ALT APPEARED ERRATIC, AND FROM DISCUSSION APPEARS OUR TCASII EQUIP OPERATED PROPERLY AND GAVE CORRECT COMMAND TO CLB. FLT PROCEEDED WITH NO FURTHER INCIDENT.

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.

FA50 experienced TCASII RA with traffic having difficulty stabilizing altitude at FL220 in ZID airspace.