B737-700
Air Traffic Control Fully Certified
Situational Awareness; Confusion
Deviation / Discrepancy - Procedural Published Material / Policy
General None Reported / Taken
Company Policy
Traffic was moderately busy and complex with uneven pairs on final requiring close attention to determine which gaps would be departure holes. After a B737-700 was airborne; I noticed that another B737 with the same callsign inbound on final was the next to land on 28R; and I had already cleared him to land. This was the first time I noticed they had the same callsigns. Since I was shipping one to departure; I did not provide cautionary advisories to either aircraft. There did not appear to be any confusion in this instance during the event sequence and the pilots readback their respective take-off/landing clearances. Since the arrival was still airborne when the departure tagged up; the departure did not acquire its datablock and LCA had to call CI-1 to advise them of the identical callsigns. [The airline] needs to use stubbed callsigns (i.e. with a letter suffix) when a continuing flight on a different aircraft leaves before the arriving flight. In the scan of my strips and the radar; I should have noticed the identical callsigns and provided the appropriate advisories to both aircraft.
SFO Controller described a duplicate flight number event with both an arrival on final and an airborne departure having an identical flight number.