Carrier route record
WNOAK→SLC
Southwest Airlines · Oakland to Salt Lake City
- Flights
- 547
- Period
- September 2025 to August 2026
- Share of route
- 34%
- Carriers
- 2
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on OAK to SLC sits in the middle of the pack with a B+. Close to three flights in four arrive on time by the DOT's definition, 2 points worse than the national rate of 77.3%. The late ones land about an hour behind schedule. That rests on 547 flights, with a median arrival 4 minutes early.
The US average over the same twelve months is 77.3%, so there is little to separate Southwest on OAK to SLC from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
75.5%
Arrivals under 15 minutes late, of 546 completed flights
Avg delay
57 min
Across delayed arrivals only, not all flights
Cancelled
0.00%
National rate is 1.89%
Whole route
87.8%
Every carrier on OAK to SLC, 1,621 flights
These figures cover 547 flights between September 2025 and August 2026. The median arrival is 4 minutes early, which is the part an average hides: most flights here are fine, and the on-time rate is decided by a tail of badly late ones. On-time means under 15 minutes late, the DOT's own threshold.
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Carrier by carrier
Southwest against every carrier on OAK to SLC
Southwest flew 547 of the 1,621 flights on OAK to SLC, about 34% of it. Its 75.5% on time is 12 points worse than the route as a whole, which runs 87.8%. Ranked by on-time rate it is last of two carriers on the route, where the range runs from SkyWest at 94.1% to Southwest at 75.5%.
Only one carrier clears this site's 365-flight floor here, so there is no comparison to draw. The table below is the full picture.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| SkyWest Airlines | 1,074 | 94.1% | 71 min | 0.19% | A+ |
| Southwest Airlines (this page) | 547 | 75.5% | 57 min | 0.00% | B+ |
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Departure window
When Southwest runs best on this route
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 44 points, against half a point between the best and worst carrier.
- 5am–8am80 flights100.0%
- 8am–11am89 flights92.1%
- 11am–2pm109 flights75.2%
- 2pm–5pm13 flights—
- 5pm–8pm95 flights75.8%
- 8pm–5am161 flights56.5%
Scale runs 50% to 100%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 56.5% on time, against 100.0% for the 5am–8am slot. By evening the aircraft flying these rotations have absorbed a full day of small delays and there is no slack left to recover in. The 8pm–5am window is the busiest, with 161 flights scheduled in it.
Across the year
Southwest on OAK to SLC through the year
December is the weak month at 51.6% on time, against 94.3% in March. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. February was the busiest month here, with 70 flights.
Across the week, Wednesday is the strongest day at 85.7% on time and Friday the weakest at 65.9%, a spread of 20 points.
Arrival by arrival
How late Southwest on OAK to SLC runs when it is late
The 134 late arrivals split 48 under half an hour, 44 between 30 and 60 minutes, and 42 an hour or more.
- 15+ min early103 flights18.9%
- Within 15 min309 flights56.6%
- 15–29 min late48 flights8.8%
- 30–59 min late44 flights8.1%
- 1–2 hours late26 flights4.8%
- 2+ hours late16 flights2.9%
Scale runs 0% to 100%.
Share of 546 completed flights by arrival against schedule.
32 of 162 late departures made up the time and arrived on time, 20% of them. Only 4 left on time and still arrived late.
The worst days
Worst days for Southwest on OAK to SLC
The latest arrival of the period was on 7 May 2026, 3 hours 50 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). On three of the five worst days the largest share was filed as a late-arriving aircraft.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 7 May 2026 | 3 hours 50 minutes | Carrier |
| 20 April 2026 | 3 hours 35 minutes | Carrier |
| 5 July 2026 | 3 hours 16 minutes | Late-arriving aircraft |
| 27 June 2026 | 3 hours 13 minutes | Late-arriving aircraft |
| 26 September 2025 | 2 hours 54 minutes | Late-arriving aircraft |
Delay causes
Why Southwest runs late on this route
Late-arriving aircraft accounts for 70% of the 7,589 delay minutes carriers reported here, and the remaining four split what is left.
- 70%Late-arriving aircraft
- 26%Carrier
- 4%National Airspace System
70% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 7,589 reported delay minutes here, that single category outweighs weather by 70 to one. The split is drawn from 7,589 reported delay minutes.
The practical consequence: the 5am–8am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 100.0% on time here.
Cancellations are rare at 0.00%, below the national 1.89% and low enough to earn the plus on the grade. Almost no flights are called off; the risk here is arriving late, not not arriving.
Connections and stage length
What a delay here costs
7.7% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last about an hour, which a normal layover absorbs.
The 588 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty.
The return leg is a different operation and performs like one: it runs 87.0% on time across 547 flights, 12 points above this direction. Departure banks, aircraft rotations and the congestion at each end all differ, so scoring the two directions together would average away a real 12 points of difference.
One caution: this is a thin sample. 547 flights over twelve months is enough to clear this site's floor but not enough to pin the rate down tightly, and a single bad week moves it by more than a point. Treat the grade as a rough reading.
What to do with this
Booking Southwest on OAK to SLC
Put together: treat all of this as provisional. 547 flights over twelve months is enough to clear this site's floor and not enough to be confident to better than a couple of points. The 75.5% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 546 completed flights over 12 months sit behind that.
Related
Where to go next
- OAK to SLC, every carrier
- Southwest on SLC to OAK, the return leg
- SkyWest Airlines on OAK to SLC94.1%
- Southwest Airlines network-wide record
- Oakland International (OAK) delay statistics
- Salt Lake City International (SLC) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.05 million flight records
Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.