Carrier route record
WNSLC→BWI
Southwest Airlines · Salt Lake City to Baltimore
- Flights
- 409
- Period
- September 2025 to August 2026
- Share of route
- 53%
- Carriers
- 2
Historical statistics for September 2025 to August 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on SLC to BWI lands a B, 6 points better than the national rate of 77.3%. About one flight in six arrives 15 minutes late or worse, and those flights are late by roughly 45 minutes on average. That rests on 409 flights, with a median arrival 8 minutes early.
Set against the rest of the country, Southwest's SLC to BWI record is 6 points better than the US average of 77.3%. That gap is worth roughly 63 fewer late arrivals for every thousand flights.
Key figures
On time
83.6%
Arrivals under 15 minutes late, of 403 completed flights
Avg delay
47 min
Across delayed arrivals only, not all flights
Cancelled
1.22%
National rate is 1.89%
Whole route
81.2%
Every carrier on SLC to BWI, 769 flights
These figures cover 409 flights between September 2025 and August 2026. The median arrival is 8 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 SLC to BWI
Southwest flew 409 of the 769 flights on SLC to BWI, most of the route. Its 83.6% on time is 2 points better than the route as a whole, which runs 81.2%. Ranked by on-time rate it is first of two carriers on the route, where the range runs from Southwest at 83.6% to Delta at 78.3%. One of those carriers flew fewer than 365 flights here, so treat their positions as rough.
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 |
|---|---|---|---|---|---|
| Southwest Airlines (this page) | 409 | 83.6% | 47 min | 1.22% | B |
| Delta Air Linesthin sample | 360 | 78.3% | 35 min | 1.94% | 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 25 points, against half a point between the best and worst carrier.
- 5am–8am42 flights97.6%
- 8am–11am27 flights—
- 11am–2pm123 flights77.5%
- 2pm–5pm65 flights73.0%
- 5pm–8pm—
- 8pm–5am152 flights88.2%
Scale runs 65% to 100%. Rows with fewer than 30 flights show a dash.
Book the early departure. Flights leaving between 5am–8am arrive on time 97.6% of the time, against 73.0% for the afternoon window. That is 25 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 8pm–5am window is the busiest, with 152 flights scheduled in it.
Across the year
Southwest on SLC to BWI through the year
August is the worst month at 64.5% on time, 29 points below May, the best at 93.5%. Summer afternoon convection and peak-season schedules land on the same weeks every year, so this is a pattern you can book around rather than a run of bad luck. February was the busiest month here, with 50 flights.
Across the week, Tuesday is the strongest day at 94.3% on time and Sunday the weakest at 69.1%, a spread of 25 points.
Arrival by arrival
How late Southwest on SLC to BWI runs when it is late
Southwest on SLC to BWI often beats the schedule: 138 of 403 completed flights, 34%, arrived 15 minutes or more early. Most of the lateness is short. 33 of the 66 late arrivals were under half an hour behind, and 14 reached an hour or more.
- 15+ min early138 flights34.2%
- Within 15 min199 flights49.4%
- 15–29 min late33 flights8.2%
- 30–59 min late19 flights4.7%
- 1–2 hours late8 flights2.0%
- 2+ hours late6 flights1.5%
Scale runs 0% to 100%.
Share of 403 completed flights by arrival against schedule.
A late pushback is often recovered here: of 86 departures that left 15 minutes late or more, 38 still arrived on time. 18 flights left on time and still arrived late.
The worst days
Worst days for Southwest on SLC to BWI
The latest arrival of the period was on 20 October 2025, 2 hours 52 minutes behind schedule; most of its delay minutes were filed as a late-arriving aircraft. The same cause led on three of the five worst days.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 20 October 2025 | 2 hours 52 minutes | Late-arriving aircraft |
| 12 October 2025 | 2 hours 42 minutes | Late-arriving aircraft |
| 18 February 2026 | 2 hours 40 minutes | Extreme weather |
| 7 November 2025 | 2 hours 28 minutes | Late-arriving aircraft |
| 8 February 2026 | 2 hours 23 minutes | Carrier |
Delay causes
Why Southwest runs late on this route
Late-arriving aircraft accounts for 53% of the 3,102 delay minutes carriers reported here, and the remaining four split what is left.
- 53%Late-arriving aircraft
- 27%Carrier
- 15%National Airspace System
- 5%Extreme weather
- 0%Security
53% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 3,102 reported delay minutes here, that single category outweighs weather by 12 to one. The split is drawn from 3,102 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 97.6% on time here.
Cancellations sit at 1.22% against a national 1.89%, which is ordinary. Diversions add another 0.24%.
Connections and stage length
What a delay here costs
Badly late arrivals are rare here: only 3.5% land an hour or more behind schedule, against 8.3% nationally. Connections built on this flight are about as safe as US domestic connections get, though a cancelled flight still ignores every layover you give it.
At 1,865 miles this is transcontinental flying, and long routes get a quiet structural advantage. Scheduled block time on a flight this length carries more padding in absolute minutes, so a twenty-minute late departure often still becomes an on-time arrival. Read the on-time rate here as slightly flattering next to a short-haul route with the same operational quality.
The return leg is a different operation and performs like one: it runs 72.8% on time across 409 flights, 11 points below 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 11 points of difference.
One caution: this is a thin sample. 409 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 SLC to BWI
Put together: treat all of this as provisional. 409 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 83.6% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 403 completed flights over 12 months sit behind that.
Related
Where to go next
- SLC to BWI, every carrier
- Southwest on BWI to SLC, the return leg
- Delta Air Lines on SLC to BWI78.3%
- Southwest Airlines network-wide record
- Salt Lake City International (SLC) delay statistics
- Baltimore/Washington International Thurgood Marshall (BWI) 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.