San Francisco (SFO) has never been a beacon of operational reliability. In fact, it has generally been one of the most unreliable airports in a part of the country where snowstorms don’t exist and thunderstorms are a true rarity. It’s the airfield design combined with the location being fog-prone that has caused so many ruined plans over the years. Now, that’s going to stop thanks to a new Federal Aviation Administration (FAA) change which impacts any airport using “Simultaneous Dependent Approaches to Closely Spaced Parallel Runways.” But don’t get too thankful, because in general this is going to be bad news for travelers.

Let us start with a satellite look at the mighty SFO to understand the original problem:

The airport has two pairs of parallel runways. In the ideal operational situation, all arrivals are on the 28s, meaning airplanes fly from the right of this photo and approach over the bay before landing to the west/northwest. Nearly all departures go off the 1s, meaning they start at the bottom and head north/northeast. Some heavier departures will use the longer 28s as well, when needed.

It’s those arrivals on the 28s that have long been the source of pain at this airport. As you can see, those runways are not far apart — a mere 750 feet. Since the separation is less than 2,500 feet, it has required implementation of special FAA procedures to increase capacity. At SFO, where capacity is at a premium, they have run slightly offset, side-by-side approaches where airplanes get much closer than would normally be allowed. It is a spectacular sight to see, but more importantly, this has kept capacity at the airport up at 54 arrivals per hour.

The problem is that this is only allowed when the weather is clear. And very often, it is not. See, Karl the Fog loves the area, and he spends a lot of time blanketing the airport, especially in the mornings. That means arrival rates get slowed dramatically, and operations are disrupted.

They’ve tried all different things to increase capacity at the airport, but now, the FAA has decided to go in an alternate direction. It is banning the simultaneous approaches outright.

In the near term, this will have an even more dramatic effect, because they are closing two runways — both of the 1/19s — for six months for rehabilitation. That means all operations will have to use the 10/28s and that forces the arrival rate down to 36 per hour.

Even when that construction is done, the expectation is that the arrival rate will only return to 45 per hour, not 54, because of this new policy. What does that mean in reality?

I pulled up Cirium schedule data to see the real impact. Here are all scheduled arrivals at the airport on a random Monday in June:

SFO Scheduled Arrivals by Hour – June 15, 2026

^{Data via Cirium}

That lower line shows the arrival rate while construction is happening. Temporary reductions are nothing new. They’re annoying, but they aren’t a huge concern on their own. Airlines can and always will change schedules to adjust when construction is being done.

But if it does only get back to 45 per hour after the construction, well, it’s still going to be a problem for the regular schedule. In particular, arrivals between 7 and 10pm are going to be awful. They are stacked pretty tight, and remember, this is only scheduled traffic. General aviation will make this worse.

What’s most remarkable about all this to me is that it has happened so quickly and seemingly so arbitrarily. People at more than one airline have told me that this was a complete surprise that was sprung on the airlines. That makes no sense at all since the airlines, especially United, will have to make schedule alterations.

I can’t help but wonder if after the Air Canada accident at LaGuardia where the airplane ran into a fire truck, they scared themselves into sacrificing airport capacity very quickly to help protect against the potential for another screw up. I’m sure they’ll deny it, but even if that is the case, there’s no real excuse for this taking the airlines by surprise.

Now, in the title of this post, I talked about upside. So… what is that upside? Well, the airport is likely now going to be much better operationally. If capacity is the same in good or bad weather, the airlines will create a schedule that works no matter what. Fog rolls in? Beautiful sunny day? It’s all the same. Delays should drop.

To be clear, this upside is in no way worth it. I just wanted to point out that an upside does exist. Airlines are going to have to cut back schedules. Options for customers will be worse. Fares will be higher. And all this to alter a system that has worked just fine for many years.

I’ve only talked about SFO here, but I imagine there is also an impact in Boston, Cleveland, Detroit, Memphis, Newark, Philadelphia, St Louis, and Seattle. By that, I mean those are airports that have parallel runways with less than 2,500 feet in between them. I don’t expect there to be big impacts there just because of how those airports operate normally, but I can’t say I know for sure.

Bigger picture, this is just another example of a government trying to make the system run well by reducing capacity. It is completely silent on long-term growth needs. The FAA should be building a system to accommodate traffic demand well into the future, but right now they are just trying to cap everything and make operations run more smoothly. We need a whole lot more than that.