Nct TRACON controller reported when two aircraft activated conflict alert on their radar display the...

Attributes
ACN	1647044
Time
Date	201905
Local Time Of Day	1801-2400
Place
Locale Reference	NCT.TRACON
State Reference	CA
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Small Aircraft High Wing 1 Eng Fixed Gear
Operating Under FAR Part	Part 91
Flight Phase	Final Approach
Route In Use	Other Instrument Approach
Flight Plan	VFR
Aircraft 2
Make Model Name	Small Aircraft High Wing 1 Eng Fixed Gear
Operating Under FAR Part	Part 91
Flight Phase	Initial Climb
Route In Use	None
Flight Plan	VFR
Person 1
Function	Approach
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 2.7
Events
Anomaly	ATC Issue All Types Conflict NMAC Deviation - Procedural Other / Unknown

Narrative:

Aircraft X was tracking the localizer back course in ZZZ at 2300 feet. Aircraft Y departed ZZZ1 southwest bound and climbing. Collision alert activated and I attempted to move aircraft X's datablock to be able to see conflicting traffic. I was unable to move the datablock. I then attempted to disable auto offset and input the wrong entry. After correctly disabling auto offset I moved aircraft X's datablock; located the conflicting traffic; and issued a traffic alert. Aircraft X's target merged with the conflicting traffic at the same altitude. Aircraft X stated over the frequency 'that was really close.' aircraft Y then called for services and was radar identified and altitude verified. The restriction of datablocks while in collision alert and auto offset enabled is unsafe and will; potentially; lead to the loss of life during time critical safety situations. Remove the restriction limiting controllers from manipulating datablock position while auto offset is on and a datablock is in collision alert.

Original NASA ASRS Text

Title: NCT TRACON Controller reported when two aircraft activated Conflict Alert on their radar display they were unable to separate the overlapped data blocks to issue appropriate control instructions and a Traffic Alert.

Narrative: Aircraft X was tracking the localizer back course in ZZZ at 2300 feet. Aircraft Y departed ZZZ1 southwest bound and climbing. Collision alert activated and I attempted to move Aircraft X's datablock to be able to see conflicting traffic. I was unable to move the datablock. I then attempted to disable auto offset and input the wrong entry. After correctly disabling auto offset I moved Aircraft X's datablock; located the conflicting traffic; and issued a traffic alert. Aircraft X's target merged with the conflicting traffic at the same altitude. Aircraft X stated over the frequency 'That was really close.' Aircraft Y then called for services and was radar identified and altitude verified. The restriction of datablocks while in collision alert and auto offset enabled is unsafe and will; potentially; lead to the loss of life during time critical safety situations. Remove the restriction limiting controllers from manipulating datablock position while auto offset is on and a datablock is in collision alert.

Data retrieved from NASA's ASRS site 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.

Nct TRACON controller reported when two aircraft activated conflict alert on their radar display they were unable to separate the overlapped data blocks to issue appropriate control instructions and a traffic alert.