Route reliability record

DEN→DTW

Denver to Detroit

Flights: 3,088
Period: July 2025 to June 2026
Distance: 1,123 mi
Carriers: 5

This route lands a B+, level with the national rate of 77.6%. Roughly one flight in four arrive 15 minutes late or worse, and those flights are late by about an hour on average. That is a workable record, not a spotless one. That rests on 3,088 flights, of which Delta Air Lines flew 1,252 at 86.2% on time.

Delta Air Lines is the most reliable of the four carriers covered here at 86.2% on time across 1,252 flights.

On time

77.6%

Arrivals under 15 minutes late, of 3,069 completed flights

Avg delay

61 min

Across delayed arrivals only, not all flights

Cancelled

0.45%

National rate is 1.81%

Best carrier

Delta

86.2% on time across 1,252 flights

These figures cover 3,088 flights between July 2025 and June 2026. The median arrival is 6 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

Which airline is most reliable on DEN to DTW

The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 86.2% of the time; Southwest Airlines manages 56.7%. Sample sizes sit next to every figure, because a two-point gap across 649 flights means less than a ten-point one.

On-time performance by carrier on DEN to DTW
Airline	Flights	On time	Avg delay	Cancelled	Grade
SkyWest Airlinesthin sample	1	100.0%	—	0.00%	A+
Delta Air Lines	1,252	86.2%	75 min	0.48%	A+
Frontier Airlines	459	80.3%	76 min	0.22%	B+
United Airlines	727	79.7%	60 min	0.00%	B+
Southwest Airlines	649	56.7%	49 min	1.08%	D

The spread between Delta and Southwest is 30 points, wide enough that it should decide the booking. On a hundred trips that is 30 more arrivals inside the on-time window.

Departure window

The best time of day to leave

Departure time matters more here than the choice of carrier. The gap between the best and worst window is 29 points, against 30 points between the best and worst carrier. Each bar is the on-time rate for flights scheduled inside that window.

5am–8am512 flights90.6%
8am–11am866 flights83.4%
11am–2pm254 flights71.5%
2pm–5pm440 flights80.8%
5pm–8pm796 flights61.4%
8pm–5am220 flights84.4%

Scale runs 55% to 95%. Rows with fewer than 30 flights show a dash.

The 5pm–8pm window is where this operation falls apart: 61.4% on time, against 90.6% 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 8am–11am window is the busiest, with 866 flights scheduled in it.

Across the year

When delays peak on this route

This route's year swings by 19 points from best month to worst, which is wide. An annual average tells you very little about the week you are actually flying, so read the strip rather than the headline if your dates are fixed.

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

July is the worst month at 70.4% on time, 19 points below November, the best at 88.9%. 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 287 flights.

Across the week, Saturday is the strongest day at 81.8% on time and Thursday the weakest at 74.9%. 7 points is a smaller lever than departure hour, but it is free.

Delay causes

Why this route gets delayed

One category carries most of the weight here. Late-arriving aircraft accounts for 53% of the 42,000 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
53%
Carrier
31%
National Airspace System
13%
Extreme weather
2%
Security
0%

53% 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 42,000 reported delay minutes here, that single category outweighs weather by 21 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 41,952 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 90.6% on time here.

Cancellations are rare at 0.45%, below the national 1.81% and low enough to earn the plus on the grade. Roughly one flight in 100 is called off; the risk here is arriving late, not not arriving.

Connections and stage length

What a delay here actually costs

7.1% 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 are the about an hour kind, which a normal layover absorbs.

The 1,123 miles between these two airports put this in the middle of the US network, around two and a half to three hours of block time. That is enough cruise to absorb a ten-minute late pushback and not enough to absorb thirty. It is also long enough that the aircraft usually flies three or four legs a day rather than six, which slows how fast delay compounds.

The return leg runs 79.7% on time across 3,089 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.

The sample behind these figures is 3,088 flights, enough that the headline rate is stable to within roughly a point. The hour-block and month splits divide that further, so read the thinner bars with more caution than the headline.

What to do with this

Booking this route

Put together: the calendar is the biggest lever here, not the carrier or the hour. November runs 88.9% on time and July 70.4%, a swing of 19 points. If the dates move at all, move them out of July before you think about anything else. 3,069 completed flights over 12 months sit behind that.

Common questions

DEN to DTW questions

How often is DEN to DTW delayed?

Roughly one flight in four arrive at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 22.4% of the 3,088 flights in this analysis, against 22.4% nationally. Delayed flights are late by about an hour on average.

Which airline is most reliable on DEN to DTW?

Delta Air Lines leads at 86.2% on time across 1,252 flights. Southwest Airlines is at the other end on 56.7%, a gap of 30 points. Sample size matters as much as the percentage: a rate built from a few hundred flights moves around far more than one built from ten thousand.

What time of day has the fewest delays on DEN to DTW?

The 5am–8am departure window is the strongest at 90.6% on time. The 5pm–8pm window is the weakest at 61.4%, 29 points behind. Later departures inherit delays from earlier flights the same aircraft has already flown, which is why the curve slopes the way it does.

How bad are July delays on DEN to DTW?

July is the weakest month at 70.4% on time, compared with 88.9% in November. Across the year that is 19 points between the best and worst months. Moving flexible dates out of that month is one of the few things that reliably helps.

Where to go next

Direction matters. DEN to DTW and DTW to DEN are scored separately because they are separate operations, with different departure banks and different aircraft. Compare the return leg.

Source: US DOT Bureau of Transportation Statistics, on-time performance data, July 2025 to June 2026. Updated monthly. How this data is collected.

Key figures