Carrier route record

WNMDW→DTW

Southwest Airlines · Chicago to Detroit

Flights: 1,053
Period: July 2025 to June 2026
Share of route: 80%
Carriers: 2

Historical statistics for July 2025 to June 2026, not live status. For today’s flights, check with Southwest Airlines.

Southwest on MDW to DTW sits in the middle of the pack with a C. Close to three flights in four arrive on time by the DOT's definition, 4 points worse than the national rate of 77.6%. The late ones land roughly 55 minutes behind schedule. That rests on 1,053 flights, with a median arrival 3 minutes early.

The national on-time rate over the same period is 77.6%, so Southwest on MDW to DTW runs 4 points behind the country as a whole. Across a thousand flights that is about 40 extra late arrivals.

On time

73.6%

Arrivals under 15 minutes late, of 1,032 completed flights

Avg delay

53 min

Across delayed arrivals only, not all flights

Cancelled

1.90%

National rate is 1.81%

Whole route

76.0%

Every carrier on MDW to DTW, 1,318 flights

These figures cover 1,053 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 MDW to DTW

Southwest flew 1,053 of the 1,318 flights on MDW to DTW, most of the route. Its 73.6% on time is 2 points worse than the route as a whole, which runs 76.0%. Ranked by on-time rate it is last of two carriers on the route, where the range runs from SkyWest at 85.2% to Southwest at 73.6%. 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.

On-time performance by carrier on MDW to DTW
Airline	Flights	On time	Avg delay	Cancelled	Grade
SkyWest Airlinesthin sample	265	85.2%	75 min	0.38%	A+
Southwest Airlines (this page)	1,053	73.6%	53 min	1.90%	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 28 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–8am52 flights86.5%
8am–11am299 flights87.8%
11am–2pm159 flights72.9%
2pm–5pm146 flights73.1%
5pm–8pm217 flights59.6%
8pm–5am180 flights63.8%

Scale runs 50% to 95%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 59.6% on time, against 87.8% 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 299 flights scheduled in it.

Across the year

Southwest on MDW to DTW through the year

Darker means more delays. Figures are on-time percentages.November best, June worst

June is the worst month at 57.6% on time, 31 points below November, the best at 88.5%. 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. October was the busiest month here, with 93 flights.

Across the week, Tuesday is the strongest day at 77.6% on time and Sunday the weakest at 70.1%. 8 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 54% of the 14,000 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.

Late-arriving aircraft
54%
Carrier
30%
National Airspace System
13%
Extreme weather
1%
Security
0%

54% 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 14,000 reported delay minutes here, that single category outweighs weather by 37 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 14,498 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 87.8% on time here.

Cancellations sit at 1.90% against a national 1.81%, which is ordinary. Diversions add another 0.09%.

Connections and stage length

What a delay here costs

7.8% 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 roughly 55 minutes, which a normal layover absorbs.

At 228 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 8am–11am window matters as much as it does.

The return leg runs 75.8% on time across 1,055 flights, within 2 points of this direction. The two legs are scored separately because they usually differ; on this city pair they happen not to.

One caution: this is a thin sample. 1,053 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 MDW to DTW

Put together: treat all of this as provisional. 1,053 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 73.6% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 1,032 completed flights over 12 months sit behind that.

Where to go next

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.

Key figures