Local controller and pilot not flying reported an unstable approach led to a go around.

Attributes
ACN	1598277
Time
Date	201812
Local Time Of Day	1801-2400
Place
Locale Reference	ATL.Airport
State Reference	GA
Environment
Flight Conditions	IMC
Aircraft 1
Make Model Name	Medium Large Transport Low Wing 2 Turbojet Eng
Operating Under FAR Part	Part 121
Flight Phase	Final Approach
Route In Use	Other Instrument Approach
Flight Plan	IFR
Person 1
Function	Local
Qualification	Air Traffic Control Fully Certified
Experience	Air Traffic Control Time Certified In Pos 1 (yrs) 4.1
Person 2
Function	Pilot Not Flying
Qualification	Flight Crew Air Transport Pilot (ATP) Flight Crew Instrument Flight Crew Multiengine
Events
Anomaly	ATC Issue All Types Aircraft Equipment Problem Less Severe Deviation - Procedural Clearance Deviation - Track / Heading All Types Inflight Event / Encounter Weather / Turbulence

Narrative:

I was on local position. Aircraft X was flying erratic; going slightly north and south of localizer but within parameters. There was a monitor in place (A80) and the tcp transfer control point was set at 1 mile. There was zero visibility; 6500+ RVR reading. Monitor O at A80 never made a transmission. Once inside a mile; I noticed on [radar display] the aircraft drifting south at altitude of 1400. I told the pilot to go around; he didn't respond initially; I made another go around transmission which the pilot did respond to. Turned the aircraft south; issued wake turbulence [caution] from a departure and handed aircraft off to approach. The asde-X amass did alert with the new system installed to warn of an aircraft lined up for a taxiway. Aircraft X appeared lined up for taxiway right.other than approach maybe being more on top of the erratic behavior of pilot outside of tcp; everything worked out with the new system installed on asde-x good. It saved a potential accident.

Original NASA ASRS Text

Title: Local Controller and pilot not flying reported an unstable approach led to a go around.

Narrative: I was on Local position. Aircraft X was flying erratic; going slightly north and south of localizer but within parameters. There was a monitor in place (A80) and the TCP transfer control point was set at 1 mile. There was zero visibility; 6500+ RVR reading. Monitor O at A80 never made a transmission. Once inside a mile; I noticed on [radar display] the aircraft drifting south at altitude of 1400. I told the pilot to go around; he didn't respond initially; I made another go around transmission which the pilot did respond to. Turned the aircraft south; issued wake turbulence [caution] from a departure and handed aircraft off to approach. The ASDE-X AMass did alert with the new system installed to warn of an aircraft lined up for a taxiway. Aircraft X appeared lined up for taxiway R.Other than approach maybe being more on top of the erratic behavior of pilot outside of TCP; everything worked out with the new system installed on ASDE-x good. It saved a potential accident.

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.