ATC equipment problem radar failed caused target jump when different remote radar site used.

Attributes
ACN	270567
Time
Date	199405
Day	Thu
Local Time Of Day	0601 To 1200
Place
Locale Reference	atc facility : cxr
State Reference	OH
Altitude	msl bound lower : 26000 msl bound upper : 26000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zob
Operator	common carrier : air carrier
Make Model Name	B727 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	cruise other
Route In Use	enroute : direct
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	DC-9 Undifferentiated or Other Model
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	climbout : intermediate altitude
Route In Use	enroute : direct
Flight Plan	IFR
Person 1
Affiliation	government : faa
Function	controller : radar
Qualification	controller : radar
Experience	controller non radar : 4 controller radar : 1
ASRS Report	270567
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	conflict : airborne less severe other anomaly other
Independent Detector	other controllera
Resolutory Action	none taken : anomaly accepted
Consequence	Other
Miss Distance	horizontal : 12000 vertical : 200
Supplementary
Primary Problem	Navigational Facility
Air Traffic Incident	other

Narrative:

Air carrier X B727 was proceeding on course swbound at FL260. DC9 was climbing off of dtw behind X. Due to a cleveland radar outage, Y's target 'jumped' toward X's target therefore making it appear that a loss of separation had occurred. It appeared as if there was only a couple mi of separation and only 200 ft vertically. When there is a radar outage, targets 'swap' with each other, jump around, etc. Is the mosaic from the more distant radar sites reliable and accurate? It was shocking to watch these 2 targets get so close so suddenly that there wasn't much that I could do.

Original NASA ASRS Text

Title: ATC EQUIP PROB RADAR FAILED CAUSED TARGET JUMP WHEN DIFFERENT REMOTE RADAR SITE USED.

Narrative: ACR X B727 WAS PROCEEDING ON COURSE SWBOUND AT FL260. DC9 WAS CLBING OFF OF DTW BEHIND X. DUE TO A CLEVELAND RADAR OUTAGE, Y'S TARGET 'JUMPED' TOWARD X'S TARGET THEREFORE MAKING IT APPEAR THAT A LOSS OF SEPARATION HAD OCCURRED. IT APPEARED AS IF THERE WAS ONLY A COUPLE MI OF SEPARATION AND ONLY 200 FT VERTICALLY. WHEN THERE IS A RADAR OUTAGE, TARGETS 'SWAP' WITH EACH OTHER, JUMP AROUND, ETC. IS THE MOSAIC FROM THE MORE DISTANT RADAR SITES RELIABLE AND ACCURATE? IT WAS SHOCKING TO WATCH THESE 2 TARGETS GET SO CLOSE SO SUDDENLY THAT THERE WASN'T MUCH THAT I COULD DO.

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.