Date: 201704
Local time of day: 0001-0600
Location: SAN.Tower, CA
Flight conditions: VMC
Light: Daylight
Aircraft: Small Transport
Operator: Air Taxi
Operating under: Part 91
Flight plan: VFR
Mission: Cargo / Freight / Delivery
Flight phase: Final Approach
Airspace: Class B SAN
ATC / advisory: Tower SAN
Second aircraft: Commercial Fixed Wing
Reporter organization: Government
Reporter function: Local
Reporter qualification: Air Traffic Control Fully Certified
Human factors: Communication Breakdown; Situational Awareness
Second reporter function: Supervisor / CIC
Anomaly: ATC Issue All Types; Conflict Airborne Conflict; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Air Traffic Control
When detected: In-flight
Result: Air Traffic Control Issued New Clearance; Air Traffic Control Separated Traffic; Flight Crew Executed Go Around / Missed Approach; Flight Crew Requested ATC Assistance / Clarification
Contributing factors: Human Factors; Airspace Structure; Airport; Procedure
Primary problem: Procedure

Narrative: Aircraft X was handed off over as a VFR inbound. I accepted the handoff and when Aircraft X checked in I advised them they were following Aircraft Y and showed a slight overtake. I cleared them to land. Close in trail of Aircraft X was Aircraft Z. They had a 'VV' in their scratch pad so as per our Letter of Agreement with SCT he was on a Visual Approach and had traffic he is following in sight. I told Aircraft Z of their overtake with Aircraft X and cleared them to land. Aircraft Z was still indicating an overtake on Aircraft X ahead so after a mile or two tracking final I advised them of their overtake and told them the speed Aircraft X was indicating. Aircraft Z then told me; 'Ok I see them now'! This confused me a bit since according to his scratch pad entry he should have had that traffic in sight before SCT switched Aircraft Z to me. Aircraft Z than began to slow. I advised Aircraft X I would need no delay off the runway due to traffic close in trail. While this was happening with Aircraft X and Aircraft Z; I had Aircraft A who was turned in behind Aircraft Z instead of extending downwind to follow his company Aircraft B on a 12 mile final. Aircraft A quickly was indicating 180 knots overtaking Aircraft Z on final. I reached out to Aircraft A who was not on my frequency. I called over to TRACON to switch the Aircraft A. As I was talking to TRACON Aircraft A checked in. I advised Aircraft A of their overtake on traffic and sent them around. Aircraft A questioned the instructions and mentioned they were not told of traffic. I sent Aircraft A around at this time as he was about 1.5 miles from the Aircraft Z. Aircraft A went around heading 275 climbing to 2500 feet. I did have all traffic in sight out the window; weather was clear and traffic was easy to spot.We used to have procedures not allowing SCT to had us off an overtake inside a five mile final. This was removed due to adding that the tower will provide visual with traffic inside of a 5 mile final. I feel that the overtakes were unsafe. The traffic even though they indicated they had visual contact with preceding traffic did NOT have visual like their scratch pads indicated. I am not sure if any of this was an operational error. I feel it was unsafe not to be talking to a [Large Transport Aircraft] following to small aircraft all inside of a 5 mile final. I would like someone to check the tapes and see if this was an operational error. I feel it was all done very poorly and with reckless regard for safety. Instead of extending Aircraft A to follow and avoiding the whole situation. These types of issues happen at SAN all the time. Very dangerous and unnecessary overtakes and switches inside of 5 miles.


Second narrative: I was the Tower Controller in Charge on duty when approach vectored Aircraft A to follow Aircraft Z. IFR separation was rapidly collapsing and there was no coordination from approach so that tower could provide visual separation. Local control reached out on frequency to Aircraft A in the hopes of slowing him but they were not on frequency. When Aircraft A finally did check on Local Control had no choice but to send Aircraft A around because runway separation would not exist. Aircraft A then commented that was the first he heard of the traffic he was following. I called the TRACON Supervisor to ask if they could find out if Aircraft A had been given the traffic but did not get a call back. At the time I did not feel it was a separation incident because Tower had the aircraft in sight the whole time. I was advised by my Supervisor today that it could be a separation incident because approach may have lost separation before our application of visual separation.The above overtake situation is not an uncommon occurrence. I understand SCT has a challenging job with the complexity and mix of traffic they work; so beyond being cognizant of the speeds/overtakes they are giving us I don't know what else to recommend.


Synopsis: SAN Tower Controllers reported receiving multiple aircraft on final from the TRACON resulting in insufficient separation.