SFO stresses the fact that its arrival capacity drops from 60 aircraft/hour to 30 aircraft per hour during poor weather. The implication is that it is dealing with an extra 30 planes per hour when it goes to a single runway for arrivals. In fact, the average arrival rate during the peak hours of a typical day is 34 arrivals/hour. In the next two years, SFO will have a new radar system (PRM) and a new approach pattern (SOIA) that will allow for arrival rates of 38-45 planes/hour even when the airport is experiencing low cloud cover. SFO’s hourly arrival rate only exceeds 42 flights/hour during 3 hours of the day and its maximum hourly arrival rate is 46 flights/hour ¹⁰.

NASA and the FAA are developing a number of new technologies that will ensure that SFO’s arrival capacity on the existing airfield exceeds the average arrival rate. If steps are taken to spread the arrivals more evenly throughout the day, then the increase in arrival capacity will lead to a significant reduction in weather-related delays. The long-term goal of NASA’s Terminal Area Program (TAP), "is to achieve the same level of airport capacity and safety associated with clear weather operation during instrument meteorological conditions."

In addition to the SOIA approach, SFO should be introducing air traffic management systems, such as FAST (final approach spacing tool) and TMA (traffic management advisor). These systems allow air traffic controllers to route and sequence planes more efficiently. TMA and FAST have permitted a 10-15% increase in arrival rates at the congested Dallas-Fort Worth airport. With the combined improvements from these systems, SFO could realize arrival rates from 40-50 flights/hour even in poor weather.

NASA, the FAA, and commercial partners are also working on satellite navigation and avoidance systems (GPS/ADS-B ) and wake vortex detection systems that will allow a greater number of planes to arrive safely in poor weather. New satellite based navigation and avoidance systems have the capability to increase safety in all phases of flight by allowing a pilot to ‘see’ all other similarly equipped aircraft in real time whether they are on the ground or in the air.

¹⁰ Calculated from Exhibit 15 (Scheduled Operations by Hour), Regional Airport System Plan (2000)

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