SFO's Runway 1R Reopens September 29 — What Actually Changes for Your Flight
Matt — Founder & Airline Pilot. Published September 23, 2026. 8 min read.
On Tuesday, September 29, San Francisco International gets its fourth runway back. Runway 1R has been closed since March 30 for a full repaving, and for most of those six months it has been one of the two biggest reasons your SFO flight ran late.
The reopening is genuine good news, and it comes ahead of schedule. It is also smaller than some of the coverage suggests. SFO does not go back to where it was in March, and if you are connecting at SFO in October you should still plan like the airport is constrained — because it is.
Here is what actually changes on September 29, what does not, and what it means for a flight you have already booked through SFO.
The One Number That Matters
Airport capacity comes down to a single figure: how many aircraft can land per hour. That number is what collapsed in the spring, and it is what recovers next week.
| Period | Arrivals per hour | What was happening |
|---|
| Before March 30, 2026 | up to 54 | Four runways, simultaneous side-by-side approaches permitted |
| March 30 – August 11 | 36 | 1R closed for repaving, and the FAA separately ended side-by-side approaches in clear weather |
| August 12 – September 28 | 42 | FAA permitted staggered parallel landings in clear weather |
| From September 29 | 45–48 | 1R reopens alongside revised procedures allowing modified parallel landings |
Two things are worth pulling out of that table.
The closure was never the whole story. SFO has said that losing 1R on its own would have cut arrivals to about 45 per hour. The drop to 36 happened because the FAA, within a day of the closure taking effect, separately discontinued simultaneous side-by-side approaches to the 28L/28R pair following a national review of closely spaced parallel operations (SFO). Two constraints, one of which had nothing to do with construction.
The recovery started in August, not this month. On August 12 the FAA began allowing staggered parallel landings in clear weather, which lifted the arrival rate immediately (SFist). If your flight has felt better since late summer, that is why.
One note on precision, because the published figures do not perfectly agree. Reporting at the time of the August change put the new rate at 42 per hour, which is the figure used above; later coverage has described that same change as reaching 45 (SFist). For the post-reopening period, SFO's own release gives 45–48, with 48 the clear-weather ceiling. Where sources conflict, the lower contemporaneous figure is used here.
What Does Not Change on September 29
This is the part worth understanding before you assume your October flight is safe.
Simultaneous side-by-side approaches are still prohibited. SFO's 28L and 28R are 750 feet apart — unusually close by modern standards. The FAA restriction that took SFO from 45 to 36 in March is being relaxed, not withdrawn. What resumes is a modified, staggered version, not the old procedure. That is precisely why the ceiling is 48 and not 54.
Low visibility still wipes out the gain. Every improvement described above applies to clear weather. When the marine layer sits on the field or a winter system drops the ceiling, SFO reverts to single-file approaches and the arrival rate falls back toward the mid-30s. A foggy morning in October will look a lot like a morning in June.
The national network still rules. Two days ago, more than 400 flights were delayed at SFO because a backup fiber cable was cut at a construction site in New Jersey and took down FAA equipment on the East Coast (SF Chronicle). SFO's runways were perfectly fine that day. No amount of local capacity protects you from a broken aircraft rotation, a crew running out of duty time, or an ATC failure three time zones away.
So How Much Better Will It Actually Feel?
Better than the summer, and close to normal on a clear day.
SFO's spokesman Doug Yakel has said that 48 arrivals per hour in clear weather should feel more or less like "normal operations", and — this is the useful detail — that the airport rarely hit 54 on a day-to-day basis even before any of this started (SFist). Scheduled demand, not the theoretical maximum, is what fills an arrival bank. If real demand peaks in the mid-40s, a 48 ceiling is not much of a constraint.
For scale, here is what the constrained period actually cost passengers. Delays at SFO averaged about 20 minutes across the five months of the closure (SFist), against roughly 5 minutes in the same period a year earlier. In the April-to-June window, 41% of flights ran 15 or more minutes late, up from about 18% a year before (SF Chronicle). Those are the numbers that should now improve.
SFO's own travel alerts page was still advising that around 30% of arrivals were running 30 or more minutes late, and still listing early October as the end of construction, at the time of writing (SFO). Expect that page to be revised after the runway returns.
What To Do If You Are Flying SFO in October
Four things, in order of how much they actually help.
- Fly early. The first departures of the day are the ones flown by aircraft that slept at the airport. Delay accumulates through the day as aircraft and crews fall behind, and that pattern is independent of runway count. This is the single highest-value choice you make when booking.
- Keep a real connection buffer. A 60-minute SFO connection was genuinely risky through the summer. It is defensible again on a clear day from September 29, but on a low-visibility morning it is still tight. If the itinerary is important, buy 90 minutes.
- Watch the weather, not the construction. From next week, the runway stops being the variable. Ceiling and visibility become the thing that decides whether SFO runs at 48 an hour or 36.
- Check the flight rather than the airport. Airport-level averages hide enormous variation between individual flights. The same route at 07:00 and at 19:00 are different risk propositions, and a specific tail number arriving from a delayed inbound is a different proposition again.
That last point is the whole reason DelayGuard exists. Our model scores a specific flight on a specific day using the aircraft's inbound history, the route, the hour, the airline, the airport and the forecast — rather than telling you that SFO is "usually fine".
The Project Itself
For completeness, since the numbers moved. The 1R rehabilitation was awarded to Granite Construction and closed the runway from March 30 for a planned six months, originally to October 2. The total project cost came in around $215 million including $92.1 million of FAA funding, revised up from the $180 million construction estimate SFO gave when it announced the closure (SF Chronicle). The work is finishing ahead of schedule, which is rare enough in airport construction to be worth noting.
Accounts of exactly how early differ — SFO framed the reopening as no later than September 29 against an original October 2 completion, and various reports have described it as two, three or five days ahead. The date that matters to travelers is September 29.
The Bottom Line
- Runway 1R reopens no later than Tuesday, September 29, 2026, ahead of the original October 2 date
- Clear-weather arrivals go to roughly 45–48 per hour, up from 42 since August and 36 through the spring
- SFO does not return to 54 per hour, because simultaneous side-by-side approaches remain prohibited
- Low visibility still forces single-file approaches at roughly 36 per hour, so foggy mornings stay bad
- Airline-side problems and national ATC disruptions are unaffected by any of this
If you want the earlier context, the April analysis of the capacity cut explains the FAA restriction in detail, and the six-month review covers what the summer actually looked like in the data.
Sources: SFO press release, September 16, 2026 · SFO travel alerts · SFist, September 17, 2026 · SFist, August 12, 2026 · ABC7 on staggered landings · KTVU on the project cost · SF Chronicle reporting on the reopening and on the September ATC outage
All articles | Flight delay prediction