Carrier route record
WNDTW→BWI
Southwest Airlines · Detroit to Baltimore
- Flights
- 784
- 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 DTW to BWI lands a B, 2 points better than the national rate of 77.6%. About one flight in five arrives 15 minutes late or worse, and those flights are late by roughly 50 minutes on average. That is a workable record, not a spotless one. That rests on 784 flights, with a median arrival 3 minutes early.
The US average over the same twelve months is 77.6%, so there is little to separate Southwest on DTW to BWI from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.
Key figures
On time
79.6%
Arrivals under 15 minutes late, of 774 completed flights
Avg delay
48 min
Across delayed arrivals only, not all flights
Cancelled
1.02%
National rate is 1.81%
Whole route
80.9%
Every carrier on DTW to BWI, 2,261 flights
These figures cover 784 flights between July 2025 and June 2026. The median arrival is 3 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.
Carrier by carrier
Southwest against every carrier on DTW to BWI
Southwest flew 784 of the 2,261 flights on DTW to BWI, about 35% of it. Its 79.6% on time is about level with the route as a whole at 80.9%. Ranked by on-time rate it is number four of five carriers on the route, where the range runs from Republic at 100.0% to Frontier at 76.9%. 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 | 100.0% | — | 7.14% | A− |
| Spirit Airlinesthin sample | 109 | 82.6% | 103 min | 0.00% | B+ |
| Delta Air Lines | 1,204 | 81.9% | 73 min | 1.50% | B |
| Southwest Airlines (this page) | 784 | 79.6% | 48 min | 1.02% | B |
| Frontier Airlinesthin sample | 150 | 76.9% | 66 min | 2.00% | B |
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 36 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–8am365 flights94.2%
- 8am–11am4 flights—
- 11am–2pm111 flights73.9%
- 2pm–5pm207 flights66.2%
- 5pm–8pm97 flights58.3%
- 8pm–5am—
Scale runs 50% to 100%. Rows with fewer than 30 flights show a dash.
The 5pm–8pm window is where this operation falls apart: 58.3% on time, against 94.2% 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 5am–8am window is the busiest, with 365 flights scheduled in it.
Across the year
Southwest on DTW to BWI through the year
June is the worst month at 58.3% on time, 31 points below January, the best at 89.2%. 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. July was the busiest month here, with 70 flights.
Across the week, Wednesday is the strongest day at 88.3% on time and Thursday the weakest at 71.8%. 17 points is a smaller lever than departure hour, but it is free.
Delay causes
Why Southwest runs late on this route
Carriers report a reason for every delay minute they cause, in five DOT categories. The split below is by minutes, not by number of flights, so a handful of very long weather delays weighs as much as many short ones. It covers 7,608 reported delay minutes.
- 42%Late-arriving aircraft
- 30%National Airspace System
- 25%Carrier
- 3%Extreme weather
- 0%Security
42% 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 7,608 reported delay minutes here, that single category outweighs weather by 14 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 7,608 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 94.2% on time here.
Cancellations sit at 1.02% against a national 1.81%, which is ordinary. Diversions add another 0.26%.
Connections and stage length
What a delay here costs
Badly late arrivals are rare here: only 4.1% land an hour or more behind schedule, against 8.1% 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 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 5am–8am window matters as much as it does.
The return leg is a different operation and performs like one: it runs 75.8% on time across 785 flights, 4 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 4 points of difference.
One caution: this is a thin sample. 784 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 DTW to BWI
Put together: treat all of this as provisional. 784 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 79.6% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 774 completed flights over 12 months sit behind that.
Related
Where to go next
- DTW to BWI, every carrier
- Southwest on BWI to DTW, the return leg
- Spirit Airlines on DTW to BWI82.6%
- Delta Air Lines on DTW to BWI81.9%
- Frontier Airlines on DTW to BWI76.9%
- Southwest Airlines network-wide record
- Detroit Metropolitan Wayne County (DTW) 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 7.04 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.