Air carrier X TCASII failed to detect heavy jet 6 mi ahead. Aircraft equipment problem TCASII.

Attributes
ACN	238665
Time
Date	199303
Day	Sat
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : ord
State Reference	IL
Altitude	msl bound lower : 5000 msl bound upper : 5000
Environment
Light	Night
Aircraft 1
Controlling Facilities	tracon : ord tower : hlg
Operator	common carrier : air carrier
Make Model Name	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Heavy Transport
Flight Phase	descent : approach
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Experience	controller radar : 12
ASRS Report	238665
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : anomaly accepted
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

Air carrier X was advised he was following a heavy jet by 6 mi. Air carrier X asked if we were getting a transponder reply on the heavy and the reply was 'yes.' air carrier X said his TCASII was not showing any traffic. At that time, the preceding traffic was 6 mi ahead, 1000 ft below the TCASII airplane. The preceding aircraft was not TCASII equipped. It is obvious that the TCASII system still has limitations. Having traffic directly ahead of and 1000 ft below would be the most potentially dangerous traffic. This TCASII aircraft did not even display traffic much less could it have issued any commands had traffic actually been a factor. The system is giving the users a dangerous false sense of security.

Original NASA ASRS Text

Title: ACR X TCASII FAILED TO DETECT HVY JET 6 MI AHEAD. ACFT EQUIP PROB TCASII.

Narrative: ACR X WAS ADVISED HE WAS FOLLOWING A HVY JET BY 6 MI. ACR X ASKED IF WE WERE GETTING A XPONDER REPLY ON THE HVY AND THE REPLY WAS 'YES.' ACR X SAID HIS TCASII WAS NOT SHOWING ANY TFC. AT THAT TIME, THE PRECEDING TFC WAS 6 MI AHEAD, 1000 FT BELOW THE TCASII AIRPLANE. THE PRECEDING ACFT WAS NOT TCASII EQUIPPED. IT IS OBVIOUS THAT THE TCASII SYS STILL HAS LIMITATIONS. HAVING TFC DIRECTLY AHEAD OF AND 1000 FT BELOW WOULD BE THE MOST POTENTIALLY DANGEROUS TFC. THIS TCASII ACFT DID NOT EVEN DISPLAY TFC MUCH LESS COULD IT HAVE ISSUED ANY COMMANDS HAD TFC ACTUALLY BEEN A FACTOR. THE SYS IS GIVING THE USERS A DANGEROUS FALSE SENSE OF SECURITY.

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.