Flight crew of medium large transport has false TCASII alert, descends accordingly but ATC says no t...

Attributes
ACN	336197
Time
Date	199605
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : vxv
State Reference	TN
Altitude	msl bound lower : 24500 msl bound upper : 26000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zid
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	climbout : intermediate altitude
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : commercial pilot : instrument pilot : private pilot : atp
Experience	flight time last 90 days : 150 flight time total : 12400 flight time type : 2400
ASRS Report	336197
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	altitude deviation : excursion from assigned altitude other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	none taken : anomaly accepted
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Climbing through FL260 we received a 'traffic, traffic' alert from our TCASII, quickly followed by 'reduce climb' and the visual indication of a target 'red square' right over us. I began immediate descent and copilot began radio xmissions to ZID. TCASII kept on warning 'descend, descend' and I descended to almost FL245 before we visually determined TCASII warning was wrong. It took the copilot 4 radio xmissions to center before they answered. They were working multiple frequencys, and couldn't hear us. They said there was no other traffic, IFR or VFR.

Original NASA ASRS Text

Title: FLC OF MLG HAS FALSE TCASII ALERT, DSNDS ACCORDINGLY BUT ATC SAYS NO TFC IN AREA.

Narrative: CLBING THROUGH FL260 WE RECEIVED A 'TFC, TFC' ALERT FROM OUR TCASII, QUICKLY FOLLOWED BY 'REDUCE CLB' AND THE VISUAL INDICATION OF A TARGET 'RED SQUARE' RIGHT OVER US. I BEGAN IMMEDIATE DSCNT AND COPLT BEGAN RADIO XMISSIONS TO ZID. TCASII KEPT ON WARNING 'DSND, DSND' AND I DSNDED TO ALMOST FL245 BEFORE WE VISUALLY DETERMINED TCASII WARNING WAS WRONG. IT TOOK THE COPLT 4 RADIO XMISSIONS TO CTR BEFORE THEY ANSWERED. THEY WERE WORKING MULTIPLE FREQS, AND COULDN'T HEAR US. THEY SAID THERE WAS NO OTHER TFC, IFR OR VFR.

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.

Flight crew of medium large transport has false TCASII alert, descends accordingly but ATC says no traffic in area.