Fwa TRACON controller reported losing radar on an aircraft when it went over the radar site.

Attributes
ACN	1482741
Time
Date	201709
Local Time Of Day	1201-1800
Place
Locale Reference	FWA.TRACON
State Reference	IN
Environment
Light	Daylight
Aircraft 1
Make Model Name	Small Aircraft Low Wing 2 Eng Retractable Gear
Operating Under FAR Part	Part 91
Flight Phase	Cruise
Flight Plan	IFR
Person 1
Function	Approach
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 7
Events
Anomaly	ATC Issue All Types Airspace Violation All Types Deviation - Procedural Published Material / Policy

Narrative:

Aircraft X was handed off from azo enroute southwest level at 8000. I pointed out the aircraft to sbn then at some point near the qtz radar site the aircraft dropped off my radar scope and I didn't notice. The aircraft never retagged as it flew southwest and into gus airspace. The controller after me was asked about aircraft X from gus. After watching the replay; it appears as if some anomaly occurred as the aircraft passed over the 'cone of silence' at the qtz site and was possibly too far from the gus site as we were on multi-mode radar feed due to fwa radar outage.possible automation issue when a site is out and aircraft passes directly over another radar site.

Original NASA ASRS Text

Title: FWA TRACON Controller reported losing radar on an aircraft when it went over the radar site.

Narrative: Aircraft X was handed off from AZO enroute southwest level at 8000. I pointed out the aircraft to SBN then at some point near the QTZ radar site the aircraft dropped off my radar scope and I didn't notice. The aircraft never retagged as it flew SW and into GUS airspace. The controller after me was asked about Aircraft X from GUS. After watching the replay; it appears as if some anomaly occurred as the aircraft passed over the 'cone of silence' at the QTZ site and was possibly too far from the GUS site as we were on multi-mode radar feed due to FWA radar outage.Possible automation issue when a site is out and aircraft passes directly over another radar site.

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.