<< >> NASA ASRS Report 686454, February 2006

P50 controller did not issue traffic to an air carrier when mode C was not received from an unknown target resulting in a TCASII RA at approximately 8500 ft.

Attributes
ACN	686454
Time
Date	200602
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : phx.airport
State Reference	AZ
Altitude	msl bound lower : 8000 msl bound upper : 8500
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tracon : p50.tracon
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	descent : intermediate altitude
Route In Use	arrival : on vectors
Flight Plan	IFR
Aircraft 2
Controlling Facilities	tracon : p50.tracon
Operator	general aviation : personal
Make Model Name	Skyhawk 172/Cutlass 172
Operating Under FAR Part	Part 91
Flight Phase	cruise : level
Flight Plan	VFR
Person 1
Affiliation	government : faa
Function	controller : approach
Qualification	controller : radar
Experience	controller radar : 24
ASRS Report	686454
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	other anomaly other
Independent Detector	aircraft equipment : tcas other controllera
Resolutory Action	none taken : anomaly accepted
Supplementary
Problem Areas	ATC Human Performance Navigational Facility FAA
Primary Problem	ATC Human Performance

Narrative:

Working 'a' arrival scope at P50; traffic as a primary target; no mode C appeared less than 3 mi from air carrier X. I watched the traffic to see movement -- no movement; false target I thought. We get a lot of false targets. I told air carrier X to contact final controller; and he acknowledged. I continued to watch the primary target; then I saw movement. Still no mode C. I leaned over to tell the final controller to call traffic and he told me; 'did you see that traffic?' which then had mode C indicating 8500 with air carrier X at 8300 ft! Air carrier X called on my frequency to report an RA with a C172. We get a lot of false targets at P50; our equipment is junk. I should have called the traffic even if I thought it was false. The thing that got me was the final controller had mode C at all times and my scope did not. I reported this to management. No one came to check out my scope or to follow up on this. Very typical of this facility.

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Original NASA ASRS Text

Title: P50 CTLR DID NOT ISSUE TFC TO AN ACR WHEN MODE C WAS NOT RECEIVED FROM AN UNKNOWN TARGET RESULTING IN A TCASII RA AT APPROX 8500 FT.

Narrative: WORKING 'A' ARR SCOPE AT P50; TFC AS A PRIMARY TARGET; NO MODE C APPEARED LESS THAN 3 MI FROM ACR X. I WATCHED THE TFC TO SEE MOVEMENT -- NO MOVEMENT; FALSE TARGET I THOUGHT. WE GET A LOT OF FALSE TARGETS. I TOLD ACR X TO CONTACT FINAL CTLR; AND HE ACKNOWLEDGED. I CONTINUED TO WATCH THE PRIMARY TARGET; THEN I SAW MOVEMENT. STILL NO MODE C. I LEANED OVER TO TELL THE FINAL CTLR TO CALL TFC AND HE TOLD ME; 'DID YOU SEE THAT TFC?' WHICH THEN HAD MODE C INDICATING 8500 WITH ACR X AT 8300 FT! ACR X CALLED ON MY FREQ TO RPT AN RA WITH A C172. WE GET A LOT OF FALSE TARGETS AT P50; OUR EQUIP IS JUNK. I SHOULD HAVE CALLED THE TFC EVEN IF I THOUGHT IT WAS FALSE. THE THING THAT GOT ME WAS THE FINAL CTLR HAD MODE C AT ALL TIMES AND MY SCOPE DID NOT. I RPTED THIS TO MGMNT. NO ONE CAME TO CHK OUT MY SCOPE OR TO FOLLOW UP ON THIS. VERY TYPICAL OF THIS FACILITY.

Data retrieved from NASA's ASRS site as of January 2009 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.