Carrier route record

DLSTL→DTW

Delta Air Lines · St. Louis to Detroit

Flights: 1,088
Period: July 2025 to June 2026
Share of route: 57%
Carriers: 5

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

Delta on STL to DTW earns an A. Close to nine flights in ten arrive inside the 15-minute window the DOT uses to define an on-time arrival, which puts it 11 points better than the national rate of 77.6%. When something does go wrong the average delay runs close to two hours. That rests on 1,088 flights, with a median arrival 15 minutes early.

Set against the rest of the country, Delta's STL to DTW record is 11 points better than the US average of 77.6%. That gap is worth roughly 106 fewer late arrivals for every thousand flights.

On time

88.2%

Arrivals under 15 minutes late, of 1,068 completed flights

Avg delay

102 min

Across delayed arrivals only, not all flights

Cancelled

1.65%

National rate is 1.81%

Whole route

81.8%

Every carrier on STL to DTW, 1,905 flights

These figures cover 1,088 flights between July 2025 and June 2026. The median arrival is 15 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

Delta against every carrier on STL to DTW

Delta flew 1,088 of the 1,905 flights on STL to DTW, most of the route. Its 88.2% on time is 6 points better than the route as a whole, which runs 81.8%. Ranked by on-time rate it is first of five carriers on the route, where the range runs from Delta at 88.2% to Republic at 0.0%. 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.

On-time performance by carrier on STL to DTW
Airline	Flights	On time	Avg delay	Cancelled	Grade
Delta Air Lines (this page)	1,088	88.2%	102 min	1.65%	A
Spirit Airlinesthin sample	36	83.3%	206 min	0.00%	B+
Southwest Airlines	593	73.6%	62 min	0.34%	C+
SkyWest Airlinesthin sample	186	71.7%	110 min	1.08%	C
Republic Airwaysthin sample	2	0.0%	37 min	0.00%	F+

Flight by flight

Delta flight numbers on STL to DTW

DL 162606:4092.4% · 347 flights

Departure window

When Delta runs best on this route

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 12 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–8am348 flights92.4%
8am–11am245 flights91.7%
11am–2pm—
2pm–5pm149 flights80.3%
5pm–8pm346 flights85.0%
8pm–5am—

Scale runs 70% to 100%. Rows with fewer than 30 flights show a dash.

Book the early departure. Flights leaving between 5am–8am arrive on time 92.4% of the time, against 80.3% for the afternoon window. That is 12 points of difference for no extra money, and it comes from the same aircraft having had no earlier flight to fall behind on. The 5am–8am window is the busiest, with 348 flights scheduled in it.

Across the year

Delta on STL to DTW through the year

Darker means more delays. Figures are on-time percentages.September best, December worst

December is the weak month at 78.3% on time, against 97.9% in September. Winter delays cluster: a single storm system can account for most of a month's shortfall, so an average December hides both very good weeks and genuinely unflyable days. October was the busiest month here, with 114 flights.

Across the week, Thursday is the strongest day at 95.0% on time and Monday the weakest at 79.1%. 16 points is a smaller lever than departure hour, but it is free.

Delay causes

Why Delta runs late on this route

One category carries most of the weight here. Carrier accounts for 49% of the 13,000 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.

Carrier
49%
Late-arriving aircraft
38%
National Airspace System
7%
Extreme weather
6%

38% 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 13,000 reported delay minutes here, that single category outweighs weather by 7 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 12,871 reported delay minutes.

The largest share of delay minutes, 49%, falls under carrier control: crew scheduling, maintenance, fuelling, baggage. Unlike weather, that is a management outcome, and it is the category where the gap between two carriers on the same schedule is genuinely earned. It accounts for 6,280 of the 13,000 delay minutes reported here.

Cancellations sit at 1.65% against a national 1.81%, which is ordinary. Diversions add another 0.18%.

Connections and stage length

What a delay here costs

6.0% 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 close to two hours, which a normal layover absorbs.

At 440 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 80.1% on time across 1,088 flights, 8 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 8 points of difference.

One caution: this is a thin sample. 1,088 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 Delta on STL to DTW

Put together: treat all of this as provisional. 1,088 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 88.2% headline is the most reliable number on the page; the hour and month splits below it are built on a few dozen flights each. 1,068 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