Flight crew of air carrier aircraft diverted from assigned altitude in response to a false TCASII alert and then subsequently overshot descent altitude when distracted by TCASII alert.

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Attributes
ACN	222178
Time
Date	199209
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : cle
State Reference	OH
Altitude	msl bound lower : 6750 msl bound upper : 10000
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other descent other
Route In Use	enroute airway : cle
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 150 flight time total : 7000 flight time type : 600
ASRS Report	222178
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 240 flight time total : 10000 flight time type : 1500
ASRS Report	221958
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : overshoot altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	controller : issued new clearance flight crew : took evasive 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:

We were level at 10000 ft with cle approach control. Without any prior alert, we received an RA to descend. (We had problems with the same thing on final approach in bos with no visual contact. (Assumed false RA since it quit quite suddenly)). We descended out of 10000 ft and advised cle approach. We did see an aircraft pass off our right, however, it appeared to be several mi away and would not have caused a conflict. The controller told us to descend to 9000 ft and then gave us a further descent to 7000 ft. We overshot 7000 ft by 250 ft and corrected back to 7000 ft. Prior to 7000 ft, TCASII had shown a yellow square and again this diverted our attention since we were never advised of the prior traffic, which approach control pointed out to us after we made a rapid descent out of 10000 ft. We were trying to determine if the TCASII was malfunctioning. There was no conflict on the overshoot at 7000 ft.

Original NASA ASRS Text

Title: FLC OF ACR ACFT DIVERTED FROM ASSIGNED ALT IN RESPONSE TO A FALSE TCASII ALERT AND THEN SUBSEQUENTLY OVERSHOT DSCNT ALT WHEN DISTRACTED BY TCASII ALERT.

Narrative: WE WERE LEVEL AT 10000 FT WITH CLE APCH CTL. WITHOUT ANY PRIOR ALERT, WE RECEIVED AN RA TO DSND. (WE HAD PROBLEMS WITH THE SAME THING ON FINAL APCH IN BOS WITH NO VISUAL CONTACT. (ASSUMED FALSE RA SINCE IT QUIT QUITE SUDDENLY)). WE DSNDED OUT OF 10000 FT AND ADVISED CLE APCH. WE DID SEE AN ACFT PASS OFF OUR R, HOWEVER, IT APPEARED TO BE SEVERAL MI AWAY AND WOULD NOT HAVE CAUSED A CONFLICT. THE CTLR TOLD US TO DSND TO 9000 FT AND THEN GAVE US A FURTHER DSCNT TO 7000 FT. WE OVERSHOT 7000 FT BY 250 FT AND CORRECTED BACK TO 7000 FT. PRIOR TO 7000 FT, TCASII HAD SHOWN A YELLOW SQUARE AND AGAIN THIS DIVERTED OUR ATTN SINCE WE WERE NEVER ADVISED OF THE PRIOR TFC, WHICH APCH CTL POINTED OUT TO US AFTER WE MADE A RAPID DSCNT OUT OF 10000 FT. WE WERE TRYING TO DETERMINE IF THE TCASII WAS MALFUNCTIONING. THERE WAS NO CONFLICT ON THE OVERSHOOT AT 7000 FT.

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.