SFO, which consistently ranks among the top five airports with the most delays in the U.S., typically lands 30 aircraft an hour in inclement weather when the maximum arrival rate is 62, FAA spokesman Ian Gregor said.
The combination of reduced visibility common in December through March and the geographical limitations that prevent SFO from modifying its several-decades-old, closely spaced runways, means planes have had to approach in a single-file line, he explained.
Under the Closely-Spaced Parallel Runways procedure, announced Monday, two aircraft can be paired together and run staggered approaches to both runways. The expected increase in poor-weather landings is four to five aircraft per hour, Gregor said.
“We don’t want to give the impression that this is going to be a panacea,” he said. “Is this the cure-all? No. Is it going to improve the situation? Yes.”
SFO has an estimated on-time arrival rate of 65 to 70 percent, according to airport spokesman Doug Yakel, and officials would like to see a boost to 75 percent.
The weather has been fair since the procedure went into effect Sept. 30, Yakel said, so, “It’s a little too early to tell what percentage improvement this may offer.”
In 2005, the airport launched the FAA’s Simultaneous Offset Instrument Approach, which similarly allowed a parallel approach when the cloud-cover ceiling was as low as 2,100 feet. That ceiling was eventually reduced to 1,600 feet. While that approach will remain in effect, the new procedure can be used in conditions with ceilings as low as 200 feet and visibility as low as 1 mile, Gregor said.
“This was something that was in the pipeline well before Asiana [Flight 214 crashed] and FAA is very good about extensively testing new procedures,” he said. “Safety is our No. 1 priority, so we’re very confident on this new procedure.”