False TCASII warning.

Attributes
ACN	295262
Time
Date	199501
Day	Mon
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : dfw
State Reference	TX
Altitude	msl bound lower : 2000 msl bound upper : 3500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : dfw
Operator	common carrier : air carrier
Make Model Name	ATR 72
Operating Under FAR Part	Part 121
Navigation In Use	Other Other
Flight Phase	cruise other descent : approach landing : missed approach
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 200 flight time total : 13000 flight time type : 500
ASRS Report	295262
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : instrument
Events
Anomaly	aircraft equipment problem : less severe altitude deviation : excursion from assigned altitude non adherence : clearance other anomaly other
Independent Detector	other controllera other flight crewa
Resolutory Action	flight crew : took evasive action none taken : unable
Consequence	faa : reviewed incident with flight crew Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Got an RA at approximately 2000 ft MSL on approach, told us to climb and showed a target right on us at '00' altitude. We initiated climb, tried to get a word in edgewise with tower (lots of traffic). Tower told us to maintain 2000 ft on the miss but we were already climbing through 3500 ft so we stopped at 3500 ft. The TCASII still said '00.' called departure. They turned us, and TCASII target stayed with us! Obviously a false target. Turned the damn thing off, restarted our hearts with electroshock, got on the ground without further incident. Wrote TCASII up in discrepancy log. The mechanics changed the box. I don't think there was a traffic conflict but you never know, hence this report. Tower told us that there was no traffic anywhere near us. Callback conversation with reporter revealed the following information: the reporter flies the ATR 72 for a large regional airline. He has flown the saab 340 for the same air carrier. He believes that the TCASII in the ATR is less sophisticated than the TCASII in the saab. For instance, he has never had a false TCASII warning in the saab, but has had several in the ATR. The reporter states that, in the ATR on the acton STAR into dfw, one can often get a false warning passing downtown fort worth. The reporter believes that this may be a reaction from a microwave tower in fort worth. He states that the latest modification to the TCASII suppresses all RA's below 1000 ft AGL. This is the first time that the reporter has had a false alarm that followed his aircraft. Changing the 'box' fixed the problem as the reporter immediately flew the aircraft later in the day.

Original NASA ASRS Text

Title: FALSE TCASII WARNING.

Narrative: GOT AN RA AT APPROX 2000 FT MSL ON APCH, TOLD US TO CLB AND SHOWED A TARGET RIGHT ON US AT '00' ALT. WE INITIATED CLB, TRIED TO GET A WORD IN EDGEWISE WITH TWR (LOTS OF TFC). TWR TOLD US TO MAINTAIN 2000 FT ON THE MISS BUT WE WERE ALREADY CLBING THROUGH 3500 FT SO WE STOPPED AT 3500 FT. THE TCASII STILL SAID '00.' CALLED DEP. THEY TURNED US, AND TCASII TARGET STAYED WITH US! OBVIOUSLY A FALSE TARGET. TURNED THE DAMN THING OFF, RESTARTED OUR HEARTS WITH ELECTROSHOCK, GOT ON THE GND WITHOUT FURTHER INCIDENT. WROTE TCASII UP IN DISCREPANCY LOG. THE MECHS CHANGED THE BOX. I DON'T THINK THERE WAS A TFC CONFLICT BUT YOU NEVER KNOW, HENCE THIS RPT. TWR TOLD US THAT THERE WAS NO TFC ANYWHERE NEAR US. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR FLIES THE ATR 72 FOR A LARGE REGIONAL AIRLINE. HE HAS FLOWN THE SAAB 340 FOR THE SAME ACR. HE BELIEVES THAT THE TCASII IN THE ATR IS LESS SOPHISTICATED THAN THE TCASII IN THE SAAB. FOR INSTANCE, HE HAS NEVER HAD A FALSE TCASII WARNING IN THE SAAB, BUT HAS HAD SEVERAL IN THE ATR. THE RPTR STATES THAT, IN THE ATR ON THE ACTON STAR INTO DFW, ONE CAN OFTEN GET A FALSE WARNING PASSING DOWNTOWN FORT WORTH. THE RPTR BELIEVES THAT THIS MAY BE A REACTION FROM A MICROWAVE TWR IN FORT WORTH. HE STATES THAT THE LATEST MODIFICATION TO THE TCASII SUPPRESSES ALL RA'S BELOW 1000 FT AGL. THIS IS THE FIRST TIME THAT THE RPTR HAS HAD A FALSE ALARM THAT FOLLOWED HIS ACFT. CHANGING THE 'BOX' FIXED THE PROB AS THE RPTR IMMEDIATELY FLEW THE ACFT LATER IN THE DAY.

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.