Air carrier X TCASII RA ghost target non adherence to ATC clearance. Evasive action taken.

Attributes
ACN	247000
Time
Date	199302
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	atc facility : ord
State Reference	IL
Altitude	msl bound lower : 5000 msl bound upper : 5000
Environment
Light	Night
Aircraft 1
Controlling Facilities	tracon : ord
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Route In Use	enroute : on vectors
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	other personnel other
Qualification	controller : radar
ASRS Report	247000
Person 2
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Experience	controller radar : 12
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : returned to intended course or assigned course
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Air carrier X was level at 5000 ft when he advised he was 'descending for traffic.' the controller told him the only traffic in the area was at 2 O'clock and 10 mi level at 8000 ft. The aircraft descended 500 ft, then returned to assigned altitude. X communication was accomplished by the TCASII aircraft after he had begun his maneuver. This particular controller states that with TCASII equipped airplanes, he builds in an extra 1000 ft of separation when able, simply to avoid unnecessary RA's. This TCASII unit sent a false RA from an aircraft 10 mi away and 3000 ft higher.

Original NASA ASRS Text

Title: ACR X TCASII RA GHOST TARGET NON ADHERENCE TO ATC CLRNC. EVASIVE ACTION TAKEN.

Narrative: ACR X WAS LEVEL AT 5000 FT WHEN HE ADVISED HE WAS 'DSNDING FOR TFC.' THE CTLR TOLD HIM THE ONLY TFC IN THE AREA WAS AT 2 O'CLOCK AND 10 MI LEVEL AT 8000 FT. THE ACFT DSNDED 500 FT, THEN RETURNED TO ASSIGNED ALT. X COM WAS ACCOMPLISHED BY THE TCASII ACFT AFTER HE HAD BEGUN HIS MANEUVER. THIS PARTICULAR CTLR STATES THAT WITH TCASII EQUIPPED AIRPLANES, HE BUILDS IN AN EXTRA 1000 FT OF SEPARATION WHEN ABLE, SIMPLY TO AVOID UNNECESSARY RA'S. THIS TCASII UNIT SENT A FALSE RA FROM AN ACFT 10 MI AWAY AND 3000 FT HIGHER.

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.