Air carrier X ghost TCASII TA RA evasive action climb in traffic pattern.

Attributes
ACN	236233
Time
Date	199303
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : psc
State Reference	WA
Altitude	msl bound lower : 1900 msl bound upper : 1900
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : psc tracon : edw
Operator	common carrier : air carrier
Make Model Name	Light Transport, High Wing, 2 Turboprop Eng
Flight Phase	other
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : local
Qualification	controller : non radar
ASRS Report	236233
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Air carrier X was approaching right downwind runway 30 and asked if there was any other traffic. I scanned the BRITE radar and traffic pattern and advised the pilot none that I was aware of. He said he had a TCASII advisory. I continued to scan the traffic pattern and radar, even the ramp areas. I told the pilot that there was nothing displayed on my radar and he was the only one on my frequency. He advised they were responding to an RA, the mode C indicated they climbed 400 to 500 ft higher. Air carrier X was midfield downwind at this time. I asked what their intentions were and the pilot said the conflict was over and they would go ahead and land. He also said the only thing they saw was a bird and he's probably squawking something else. It may have been a ground based transponder in an aircraft or at the avionics shop, or it may have been a ghost target.

Original NASA ASRS Text

Title: ACR X GHOST TCASII TA RA EVASIVE ACTION CLB IN TFC PATTERN.

Narrative: ACR X WAS APCHING R DOWNWIND RWY 30 AND ASKED IF THERE WAS ANY OTHER TFC. I SCANNED THE BRITE RADAR AND TFC PATTERN AND ADVISED THE PLT NONE THAT I WAS AWARE OF. HE SAID HE HAD A TCASII ADVISORY. I CONTINUED TO SCAN THE TFC PATTERN AND RADAR, EVEN THE RAMP AREAS. I TOLD THE PLT THAT THERE WAS NOTHING DISPLAYED ON MY RADAR AND HE WAS THE ONLY ONE ON MY FREQ. HE ADVISED THEY WERE RESPONDING TO AN RA, THE MODE C INDICATED THEY CLBED 400 TO 500 FT HIGHER. ACR X WAS MIDFIELD DOWNWIND AT THIS TIME. I ASKED WHAT THEIR INTENTIONS WERE AND THE PLT SAID THE CONFLICT WAS OVER AND THEY WOULD GO AHEAD AND LAND. HE ALSO SAID THE ONLY THING THEY SAW WAS A BIRD AND HE'S PROBABLY SQUAWKING SOMETHING ELSE. IT MAY HAVE BEEN A GND BASED XPONDER IN AN ACFT OR AT THE AVIONICS SHOP, OR IT MAY HAVE BEEN A GHOST TARGET.

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.