San Francisco delays ground 300 flights

Flights at San Francisco International Airport got snarled Friday for a very Bay Area reason — low clouds. But the effect was much bigger than a little fog over the runway. The FAA put SFO into a ground delay program, which means planes headed there were held at their departure airports instead of all arriving at once and clogging the sky. By midday, hundreds of flights were running late, and the disruption was set to last into the night. ### What actually happened at SFO? The FAA issued a ground delay program for SFO on Friday, May 8, because of “low ceilings” — basically a cloud layer low enough to reduce how efficiently planes can land. The active window ran from 9:49 a.m. to 11:59 p.m. PDT, and the FAA’s public status page showed average delays of about 70 minutes. Local coverage said more than 300 flights had already been delayed by late morning. (nasstatus.faa.gov) ### Why do low clouds cause such a mess? SFO is unusually sensitive to this kind of weather. The airport’s parallel runways are close together, which is fine in clear conditions, but low cloud ceilings can force controllers to increase spacing between arriving aircraft and reduce how many planes can land each hour. So the problem is not that planes cannot land at all — it’s that the airport suddenly handles fewer of them, and the schedule falls behind fast. (nasstatus.faa.gov) ### What is a ground delay program? It sounds dramatic, but it is really a traffic-management tool. Instead of letting dozens of flights depart for San Francisco and then circle in holding patterns, the FAA assigns controlled departure times at the origin airports. That keeps the airspace safer and more orderly, but it also means delays spread far beyond San Francisco because a plane leaving Chicago, Denver, or Seattle may sit on the ground waiting for its slot. (hoodline.com) ### How bad did it get? Bad enough that it was not just a few late arrivals on the board. Coverage during the day described hundreds of delayed flights, with disruptions expected to continue through the afternoon and evening. One report said more than 200 flights were already delayed by 11 a.m.; another put the total above 300 later in the morning. That is the kind of volume that starts breaking connections, crew timing, and aircraft rotations for the rest of the day. (hoodline.com) ### Why does SFO keep having this problem? Because the airport sits right next to the Bay and deals constantly with marine-layer weather. Turns out “routine fog” is not routine for airline schedules when an airport is already running close to capacity. SFO has had similar FAA delay programs this year for other weather events too, which shows the bigger issue — there is not much slack in the system when weather trims arrival rates. (hoodline.com) ### What should travelers take from this? The main thing is that a weather delay at SFO often starts before your plane ever leaves another city. If your flight was headed to San Francisco on Friday, the delay may have shown up as late boarding somewhere else, not dramatic weather at the airport itself. That is why airlines and the airport kept pushing the same advice — check your carrier status directly and expect knock-on delays even if your route looked fine earlier in the day. (hoodline.com) ### Bottom line This was not a systems outage or a security scare. It was a classic SFO weather squeeze — low clouds, fewer arrivals, then a nationwide queue. And because SFO’s runway setup is so vulnerable to that squeeze, a gray morning over the Bay can still throw off flights across the country. (nasstatus.faa.gov) (flysfo.com)