Carrier route record
WNBWI→SLC
Southwest Airlines · Baltimore to Salt Lake City
- 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 BWI to SLC sits in the middle of the pack with a C. About seven flights in ten arrive on time by the DOT's definition, 5 points worse than the national rate of 77.3%. The late ones land roughly 50 minutes behind schedule. That rests on 409 flights, with a median arrival 2 minutes late.
The national on-time rate over the same period is 77.3%, so Southwest on BWI to SLC runs 5 points behind the country as a whole. Across a thousand flights that is about 45 extra late arrivals.
Key figures
On time
72.8%
Arrivals under 15 minutes late, of 401 completed flights
Avg delay
52 min
Across delayed arrivals only, not all flights
Cancelled
1.71%
National rate is 1.89%
Whole route
76.3%
Every carrier on BWI to SLC, 769 flights
These figures cover 409 flights between September 2025 and August 2026. Beyond the headline rate, 8.5% of arrivals land a full hour or more behind schedule, against 8.3% nationally.
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Carrier by carrier
Southwest against every carrier on BWI to SLC
Southwest flew 409 of the 769 flights on BWI to SLC, most of the route. Its 72.8% on time is 4 points worse than the route as a whole, which runs 76.3%. Ranked by on-time rate it is last of two carriers on the route, where the range runs from Delta at 80.2% to Southwest at 72.8%. 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 |
|---|---|---|---|---|---|
| Delta Air Linesthin sample | 360 | 80.2% | 62 min | 1.94% | B |
| Southwest Airlines (this page) | 409 | 72.8% | 52 min | 1.71% | C |
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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 24 points, against half a point between the best and worst carrier.
- 5am–8am8 flights—
- 8am–11am161 flights81.6%
- 11am–2pm87 flights74.1%
- 2pm–5pm37 flights70.3%
- 5pm–8pm74 flights58.9%
- 8pm–5am42 flights57.5%
Scale runs 50% to 85%. Rows with fewer than 30 flights show a dash.
The 8pm–5am window is where this operation falls apart: 57.5% on time, against 81.6% for the 8am–11am 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 8am–11am window is the busiest, with 161 flights scheduled in it.
Across the year
Southwest on BWI to SLC through the year
Delays peak in March, when the on-time rate falls to 45.9%. January is the strongest month at 86.5%. Moving a flexible trip across that boundary buys 41 points. February was the busiest month here, with 50 flights.
Across the week, Tuesday is the strongest day at 83.0% on time and Wednesday the weakest at 65.4%, a spread of 18 points.
Arrival by arrival
How late Southwest on BWI to SLC runs when it is late
The 109 late arrivals split 37 under half an hour, 38 between 30 and 60 minutes, and 34 an hour or more.
- 15+ min early67 flights16.7%
- Within 15 min225 flights56.1%
- 15–29 min late37 flights9.2%
- 30–59 min late38 flights9.5%
- 1–2 hours late28 flights7.0%
- 2+ hours late6 flights1.5%
Scale runs 0% to 100%.
Share of 401 completed flights by arrival against schedule.
A late pushback is often recovered here: of 129 departures that left 15 minutes late or more, 43 still arrived on time. In the other direction, 23 flights left on time yet arrived 15 minutes late or more, so that delay built up after pushback: in the air, in a holding pattern or on the ground at SLC.
The worst days
Worst days for Southwest on BWI to SLC
The latest arrival of the period was on 16 March 2026, 5 hours 18 minutes behind schedule; most of its delay minutes were filed as carrier-caused (crew, maintenance, fuelling, baggage). The five worst days are spread across March, December, June and July, with no single month standing out.
| Date | Arrived late by | Largest filed cause |
|---|---|---|
| 16 March 2026 | 5 hours 18 minutes | Carrier |
| 14 December 2025 | 2 hours 47 minutes | Carrier |
| 19 June 2026 | 2 hours 41 minutes | Late-arriving aircraft |
| 5 December 2025 | 2 hours 34 minutes | Extreme weather |
| 30 July 2026 | 2 hours 14 minutes | Late-arriving aircraft |
Delay causes
Why Southwest runs late on this route
Carrier accounts for 44% of the 5,682 delay minutes carriers reported here, and the remaining four split what is left.
- 44%Carrier
- 29%Late-arriving aircraft
- 22%National Airspace System
- 4%Extreme weather
- 1%Security
The largest share of delay minutes, 44%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. It accounts for 2,516 of the 5,682 delay minutes reported here. The split is drawn from 5,682 reported delay minutes.
The practical consequence: the 8am–11am departure is the one that starts clean. Its aircraft has no earlier leg to be late from, which is exactly why that window shows 81.6% on time here.
Cancellations sit at 1.71% against a national 1.89%, which is ordinary. Diversions add another 0.24%.
Connections and stage length
What a delay here costs
8.5% 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 roughly 50 minutes, which a normal layover absorbs.
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 83.6% on time across 409 flights, 11 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 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 BWI to SLC
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 72.8% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 401 completed flights over 12 months sit behind that.
Related
Where to go next
- BWI to SLC, every carrier
- Southwest on SLC to BWI, the return leg
- Delta Air Lines on BWI to SLC80.2%
- Southwest Airlines network-wide record
- Baltimore/Washington International Thurgood Marshall (BWI) delay statistics
- Salt Lake City International (SLC) delay statistics
- The best time of day to fly, according to 7.05 million flight records
- Connecting flights: how much buffer the data says you need
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.