Carrier route record

DLDTW→IAH

Delta Air Lines · Detroit to Houston

Flights: 1,322
Period: July 2025 to June 2026
Share of route: 62%
Carriers: 5

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

Delta on DTW to IAH 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 about an hour on average. That is a workable record, not a spotless one. That rests on 1,322 flights, with a median arrival 6 minutes early.

The US average over the same twelve months is 77.6%, so there is little to separate Delta on DTW to IAH from the country as a whole. The variation that matters here is internal: which carrier, and what time of day.

On time

79.8%

Arrivals under 15 minutes late, of 1,308 completed flights

Avg delay

55 min

Across delayed arrivals only, not all flights

Cancelled

0.83%

National rate is 1.81%

Whole route

79.7%

Every carrier on DTW to IAH, 2,129 flights

These figures cover 1,322 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

Delta against every carrier on DTW to IAH

Delta flew 1,322 of the 2,129 flights on DTW to IAH, most of the route. Its 79.8% on time is about level with the route as a whole at 79.7%. Ranked by on-time rate it is number two of five carriers on the route, where the range runs from United at 87.0% to Frontier at 65.5%. 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 DTW to IAH
Airline	Flights	On time	Avg delay	Cancelled	Grade
United Airlinesthin sample	281	87.0%	53 min	1.42%	A
Delta Air Lines (this page)	1,322	79.8%	55 min	0.83%	B+
Spirit Airlines	403	78.5%	85 min	1.74%	B
SkyWest Airlinesthin sample	3	66.7%	19 min	0.00%	C+
Frontier Airlinesthin sample	120	65.5%	73 min	0.83%	C+

Flight by flight

Delta flight numbers on DTW to IAH

DL 163320:1579.1% · 364 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 16 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–8am1 flights—
8am–11am364 flights85.6%
11am–2pm299 flights86.5%
2pm–5pm333 flights70.5%
5pm–8pm3 flights—
8pm–5am322 flights76.7%

Scale runs 60% to 90%. Rows with fewer than 30 flights show a dash.

The best window here is not the first bank but the 11am–2pm slot at 86.5% on time, ahead of 2pm–5pm at 70.5%. Where the curve peaks mid-day rather than at dawn, the constraint is usually congestion at one end rather than the aircraft's own rotation. The 8am–11am window is the busiest, with 364 flights scheduled in it.

Across the year

Delta on DTW to IAH through the year

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

December is the weak month at 64.4% on time, against 92.5% 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. March was the busiest month here, with 120 flights.

Across the week, Tuesday is the strongest day at 81.7% on time and Friday the weakest at 77.1%. 5 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 15,000 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%
National Airspace System
31%
Late-arriving aircraft
16%
Extreme weather
4%
Security
0%

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 7,239 of the 15,000 delay minutes reported here. The split is drawn from 14,634 reported delay minutes.

Cancellations are rare at 0.83%, 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 costs

6.4% 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.

The 1,075 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 82.3% on time across 1,322 flights, within 3 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 1,322 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 Delta on DTW to IAH

Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 92.5% on time and December 64.4%, a swing of 28 points. If the dates move at all, move them out of December before you think about anything else. 1,308 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