Date: 201307
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Aircraft: Light Sport Aircraft
Operator: Personal
Operating under: Part 91
Flight plan: VFR
Flight phase: Landing
Airspace: Class D ZZZ
ATC / advisory: Tower ZZZ
Second aircraft: Gulfstream G100/G150 (IAI 1125 Astra)
Reporter organization: Government
Reporter function: Ground
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Situational Awareness
Second reporter function: Local
Anomaly: Conflict NMAC
Detector: Person Air Traffic Control; Person Flight Crew
Result: Air Traffic Control Issued New Clearance
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: I was working the Ground Control position and the airport was in west traffic Runway 21 in use. Local had what appeared to be 3 aircraft doing pattern work on the south side and 1 or 2 in the down wind on the north side. Everything was flowing smooth until the TRACON started feeding us a string of IFR jets inbound to the airport. The spacing of the jet arrivals was starting to make it difficult to mix the slower single prop traffic in the down winds. Local Control sequenced a light sport in front of a G4 and it was going to be close due to a huge speed difference. The Local Controller instructed the G4 to S turn and reduce speed for spacing and the pilot did an amazing job. However; the overtake was just too great. I watched it as long as I felt I could and finally said to Local; 'this is not going to work'. With the light sport just over the fence and the G4 at what appeared to be 1/4 mile final the Local Controller told the light sport to go-around. The pilot of light sport stayed over the runway at approximately 30 AGL. At this point the CIC; as well as me; were telling the local Controller to send the G4 around. Local told the light sport to go-around again before realizing that that will not work either and then sends the G4 around. The G4 passed overtop of the light sport by what appeared to be less than 100 FT mid field with both aircraft still over the runway. Both aircraft later landed without incident.I firmly believe that the Local Controllers' lack of knowledge when it comes to aircraft operation was directly linked to this incident. Further familiarization with aircraft performance and pilot work load is a must as well as learning to recognize when a loss so acceptable separation is about to occur and take the right action to fix it as soon as possible.


Second narrative: Prior to speaking with the G4; I had several IFR jets inbound to the airport. I also had several VFR aircraft; a light sport aircraft being one of them that I had to pull off final or extend downwind to allow the IFR jets to land. I did not want to delay the light sport landing again; so I attempted to make him first so I asked the G4 to reduce speed as much as practical. I then told the light sport he was cleared to land but to expect minimal time on the runway. The light sport requested a touch and go which I replied that in order to do a touch and go he would have to make a right turn to join the north downwind to follow the jet. He replied he would make the full stop and continue inbound. On three mile final the G4 seemed a little close so I requested he make an S-turn to the right which he complied with. The light sport was on 1/2 mile final when I asked the Gulfstream for the S turn to the right so I felt like I had enough spacing and cleared the light sport to land. I then cleared the G4 to land and he responded that he would keep it coming. Once the light sport crossed the threshold it seemed as if he was having difficulty getting the airplane on the ground at that point the CIC and Ground Controller were yelling for me to send him around; thinking they were telling me to send the light sport around I told him to start a climb to go-around. After listening to the tape; I found out that he then asked me to verify that I wanted him to go-around but I did not hear the light sport ask me to repeat the instructions. My plan was to send the light sport around and land the Gulfstream because I felt it was safer to have one in the air and one on the ground rather than send them both around and possibly cause an accident. The CIC noticed that the light sport was not climbing and then the CIC and Ground Controller yelled for me to send the G4 around which I then did and I gave him instructions to make right traffic and keep his turn inside the shoreline. The light sport was at A2 when I then heard him ask me to verify I wanted him to go-around and I told him yes because I did not want to tell him to land which such little runway left and cause an accident. I would just recommend being more aware of pilot and aircraft capabilities. Once the light sport seemed like he was having difficulty landing I should have sent the G4 around. I should not have adjusted anything and just made the light sport go behind the G4.


Synopsis: Tower Controller described a pilot filed NMAC during a confused go-around instruction; the reporter citing the operating Controllers lack of experience as a major factor in this event.