<< >> NASA ASRS Report 187031, August 1991

Air carrier mdt received a false TCASII TA on short final to runway 5L at rdu. Says this is the second time this has happened in the same location.

Attributes
ACN	187031
Time
Date	199108
Day	Thu
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : rdu
State Reference	NC
Altitude	agl bound lower : 500 agl bound upper : 700
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Controlling Facilities	tower : rdu
Operator	common carrier : air carrier
Make Model Name	Medium Transport, High Wing, 2 Turboprop Eng
Flight Phase	descent other landing 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 : 150 flight time total : 6400
ASRS Report	187031
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	other flight crewa
Resolutory Action	aircraft : equipment problem dissipated
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

TCASII phantom TA occurred short final 700 ft to 500 ft AGL. Yellow filled in box 100 ft above descending approximately 2 mi ahead converging. At 500 ft is disappeared. We also got the aural TA. Visual inspection showed no aircraft ahead of us on final. This is the second phantom alert I've got, same airport, runway, altitude. Solution: amend TCASII procedure to switch to standby on final approach. Option: there may be some kind of spurious radio frequency radiating from the ground in this vicinity causing this to happen. Callback conversation with reporter revealed the following information: reporter has not only received a false warning on approach to runway 5L but it has also happened on approach to runway 23R. Reporter says it was not always the same aircraft but was always the same type aircraft. The company fleet is not fully equipped yet but all installations are the same.

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Original NASA ASRS Text

Title: ACR MDT RECEIVED A FALSE TCASII TA ON SHORT FINAL TO RWY 5L AT RDU. SAYS THIS IS THE SECOND TIME THIS HAS HAPPENED IN THE SAME LOCATION.

Narrative: TCASII PHANTOM TA OCCURRED SHORT FINAL 700 FT TO 500 FT AGL. YELLOW FILLED IN BOX 100 FT ABOVE DSNDING APPROX 2 MI AHEAD CONVERGING. AT 500 FT IS DISAPPEARED. WE ALSO GOT THE AURAL TA. VISUAL INSPECTION SHOWED NO ACFT AHEAD OF US ON FINAL. THIS IS THE SECOND PHANTOM ALERT I'VE GOT, SAME ARPT, RWY, ALT. SOLUTION: AMEND TCASII PROC TO SWITCH TO STANDBY ON FINAL APCH. OPTION: THERE MAY BE SOME KIND OF SPURIOUS RADIO FREQ RADIATING FROM THE GND IN THIS VICINITY CAUSING THIS TO HAPPEN. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: RPTR HAS NOT ONLY RECEIVED A FALSE WARNING ON APCH TO RWY 5L BUT IT HAS ALSO HAPPENED ON APCH TO RWY 23R. RPTR SAYS IT WAS NOT ALWAYS THE SAME ACFT BUT WAS ALWAYS THE SAME TYPE ACFT. THE COMPANY FLEET IS NOT FULLY EQUIPPED YET BUT ALL INSTALLATIONS ARE THE SAME.

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.