Carrier route record
WNBWI→DTW
Southwest Airlines · Baltimore to Detroit
- Flights
- 785
- Period
- July 2025 to June 2026
- Share of route
- 35%
- Carriers
- 5
Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.
Southwest on BWI to DTW 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 77.6%. The late ones land about an hour behind schedule. That rests on 785 flights, with a median arrival right on schedule.
The US average over the same twelve months is 77.6%, so there is little to separate Southwest on BWI to DTW from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
75.8%
Arrivals under 15 minutes late, of 770 completed flights
Avg delay
57 min
Across delayed arrivals only, not all flights
Cancelled
1.91%
National rate is 1.81%
Whole route
81.7%
Every carrier on BWI to DTW, 2,257 flights
These figures cover 785 flights between July 2025 and June 2026. On-time means an arrival less than 15 minutes after the scheduled gate time, the same threshold the Department of Transportation uses in its own reports. Cancelled and diverted flights are excluded from the on-time rate and counted separately, which is why the cancellation column matters on its own.
Carrier by carrier
Southwest against every carrier on BWI to DTW
Southwest flew 785 of the 2,257 flights on BWI to DTW, about 35% of it. Its 75.8% on time is 6 points worse than the route as a whole, which runs 81.7%. Ranked by on-time rate it is number four of five carriers on the route, where the range runs from Republic at 92.3% to Frontier at 73.1%. Three 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 |
|---|---|---|---|---|---|
| Republic Airwaysthin sample | 14 | 92.3% | 17 min | 7.14% | A− |
| Delta Air Lines | 1,204 | 86.8% | 103 min | 1.66% | A |
| Spirit Airlinesthin sample | 106 | 77.1% | 104 min | 0.94% | B+ |
| Southwest Airlines (this page) | 785 | 75.8% | 57 min | 1.91% | B |
| Frontier Airlinesthin sample | 148 | 73.1% | 66 min | 2.03% | C |
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 37 points, against half a point between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.
- 5am–8am—
- 8am–11am162 flights85.1%
- 11am–2pm151 flights92.6%
- 2pm–5pm73 flights74.0%
- 5pm–8pm36 flights55.9%
- 8pm–5am363 flights66.9%
Scale runs 45% to 100%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 55.9% on time, against 92.6% for the 11am–2pm 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 363 flights scheduled in it.
Across the year
Southwest on BWI to DTW through the year
September is the best month on the calendar at 88.2% on time. Shoulder season thins the schedule and takes the summer weather with it, and the operation gets its margin back. August was the busiest month here, with 71 flights.
Across the week, Wednesday is the strongest day at 81.6% on time and Sunday the weakest at 66.1%. 16 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Southwest runs late on this route
One category carries most of the weight here. Late-arriving aircraft accounts for 57% of the 10,000 delay minutes carriers reported, and the remaining four split what is left. The split is by minutes rather than by flights, so a few very long delays count for as much as many short ones.
- 57%Late-arriving aircraft
- 27%Carrier
- 13%National Airspace System
- 2%Extreme weather
- 0%Security
57% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. That is a cascade, and cascades start small and grow through the day. Across 10,000 reported delay minutes here, that single category outweighs weather by 34 to one. It is the strongest argument for booking the first departure of the morning, when the aircraft has been sitting at the gate overnight with nothing to inherit. The split is drawn from 10,063 reported delay minutes.
Cancellations sit at 1.91% against a national 1.81%, which is ordinary. Diversions add another 0.00%.
Connections and stage length
What a delay here costs
6.8% of arrivals land an hour or more late, close to the national 8.1%. That is the figure that decides a connection, and it says 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.
At 409 miles this is a short hop, and stage length matters more than it looks. A flight this short spends under two hours in the air, which leaves almost nothing to claw back a late pushback with. Delay here is decided on the ground, in the turn, which is why the 11am–2pm window matters as much as it does.
The return leg is a different operation and performs like one: it runs 79.6% on time across 784 flights, 4 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 4 points of difference.
One caution: this is a thin sample. 785 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 DTW
Put together: treat all of this as provisional. 785 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 75.8% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 770 completed flights over 12 months sit behind that.
Related
Where to go next
- BWI to DTW, every carrier
- Southwest on DTW to BWI, the return leg
- Delta Air Lines on BWI to DTW86.8%
- Spirit Airlines on BWI to DTW77.1%
- Frontier Airlines on BWI to DTW73.1%
- Southwest Airlines network-wide record
- Baltimore/Washington International Thurgood Marshall (BWI) delay statistics
- Detroit Metropolitan Wayne County (DTW) delay statistics
- Why the first flight of the morning is statistically safest
- The best time of day to fly, according to 7.04 million flight records
Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Last updated 15 September 2026; recomputed monthly. How this data is collected.