Air carrier X TCASII RA descended from ghost target. Unauthorized descent from assigned altitude.

Attributes
ACN	247004
Time
Date	199304
Day	Fri
Local Time Of Day	0001 To 0600
Place
Locale Reference	atc facility : ord
State Reference	IL
Altitude	msl bound lower : 10000 msl bound upper : 10000
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
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Experience	controller radar : 6
ASRS Report	247004
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	altitude deviation : excursion from assigned altitude non adherence : clearance
Independent Detector	aircraft equipment other aircraft equipment : unspecified
Resolutory Action	flight crew : took evasive action
Consequence	Other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Air carrier X inbound to ord descended 600 ft in response to an RA. There was no traffic.

Original NASA ASRS Text

Title: ACR X TCASII RA DSNDED FROM GHOST TARGET. UNAUTH DSCNT FROM ASSIGNED ALT.

Narrative: ACR X INBOUND TO ORD DSNDED 600 FT IN RESPONSE TO AN RA. THERE WAS NO TFC.

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.