An air carrier mdt climbed in response to a false TCASII command.

Attributes
ACN	232371
Time
Date	199301
Day	Wed
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : ord
State Reference	IL
Altitude	msl bound lower : 5000 msl bound upper : 5300
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : ord
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport
Flight Phase	cruise other
Route In Use	departure 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 : 210 flight time total : 6020
ASRS Report	232371
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
ASRS Report	232370
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	other controllera other flight crewa other other : unspecified
Resolutory Action	flight crew : overcame equipment problem none taken : anomaly accepted
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

TCASII issued TA showing intruder aircraft at 12-1 O'clock and 3 mi, 200 ft below our altitude. TCASII issued RA 'climb, climb, climb,' when intruder was approximately 1 mi from our aircraft still showing 200 ft below our altitude. Crew initiated climb of 2000 FPM to match TCASII RA and immediately notified ATC of our deviation. As we approached 5300 ft, RA disappeared and aircraft was descended back to 5000 ft. ATC notified us that he showed no aircraft in our vicinity except for departure traffic above our altitude. Crew failed to pick up traffic that TCASII displayed. TCASII gave no 'clear of conflict' message once RA disappeared.

Original NASA ASRS Text

Title: AN ACR MDT CLBED IN RESPONSE TO A FALSE TCASII COMMAND.

Narrative: TCASII ISSUED TA SHOWING INTRUDER ACFT AT 12-1 O'CLOCK AND 3 MI, 200 FT BELOW OUR ALT. TCASII ISSUED RA 'CLB, CLB, CLB,' WHEN INTRUDER WAS APPROX 1 MI FROM OUR ACFT STILL SHOWING 200 FT BELOW OUR ALT. CREW INITIATED CLB OF 2000 FPM TO MATCH TCASII RA AND IMMEDIATELY NOTIFIED ATC OF OUR DEV. AS WE APCHED 5300 FT, RA DISAPPEARED AND ACFT WAS DSNDED BACK TO 5000 FT. ATC NOTIFIED US THAT HE SHOWED NO ACFT IN OUR VICINITY EXCEPT FOR DEP TFC ABOVE OUR ALT. CREW FAILED TO PICK UP TFC THAT TCASII DISPLAYED. TCASII GAVE NO 'CLR OF CONFLICT' MESSAGE ONCE RA DISAPPEARED.

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.