Skyhawk 172/Cutlass 172
Air Traffic Control Fully Certified
Other / Unknown
Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Executed Go Around / Missed Approach
Human Factors; Chart Or Publication; Procedure; Weather
A C172 was holding short for release. LAX gave the release but there was a jet on final that would have lost separation if and when he went around so I told the Flight Data Controller to let LAX know that I would depart the C172 after that aircraft landed. The Citation landed without any issues and I was briefed that no one had gone missed even though the weather was marginal. I put the C172 in position and told him about the twin Cessna on final that I previously slowed to make the situation work. I departed the C172 and switched him to Departure. The twin Cessna on final started to close the gap and separation was most likely lost when the twin Cessna declared that he was going missed. Their error was a misjudgment on my part. Having not seen the situation in some time and pressed against a release window; I forced the issue. I believe that the approach plate for this airport is a contributing factor to my error and others like it at SMO. It is published as a circling approach but the circle is never allowed. Pilots that are unfamiliar with that fact; tend to not fly the approach to minimums because they assume they can circle. This is the cause of a large number of missed approaches at this airport.
SMO Controller described a loss of separation event during marginal weather when spacing judgement was flawed; the reporter noting the published approach chart could be a contributing factor.