Carrier performance at one airport
DL→IAH
Delta Air Lines at George Bush Intercontinental
- Departures
- 8,429
- Period
- September 2025 to August 2026
- Routes
- 7
- Rank here
- #1 of 11
Delta Air Lines at Houston lands a B, 4 points better than the national rate of 77.3%. About one flight in five arrives 15 minutes late or worse, and those flights are late by an hour and a half on average. That rests on 8,429 flights, of which Delta Air Lines flew 8,429 at 81.0% on time.
Measured against the airport rather than the country, Delta Air Lines runs 2 points ahead of the 79.1% weighted average across all carriers at IAH. That is the comparison worth making: every operator here works the same runways, the same airspace and the same weather.
Key figures
On time
81.0%
8,242 completed departures
Avg delay
83 min
Across delayed flights only
Cancelled
1.90%
At IAH, this carrier only
Rank here
#1
Of 11 carriers clearing the floor at IAH
These figures cover 8,429 flights between September 2025 and August 2026. The median arrival is 8 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.
Against the competition
Every carrier at IAH, ranked
The choice of carrier is not cosmetic here. Delta Air Lines arrives on time 81.0% of the time; JetBlue Airways manages 50.5%. Sample sizes sit next to every figure, because a two-point gap across 835 flights means less than a ten-point one.
| Airline | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| Delta Air Lines (this page) | 8,429 | 81.0% | 83 min | 1.90% | B |
| Alaska Airlines | 1,195 | 80.6% | 55 min | 0.67% | B+ |
| United Airlines | 74,201 | 80.6% | 63 min | 0.55% | B+ |
| Envoy Air | 1,270 | 78.0% | 91 min | 1.81% | B |
| SkyWest Airlines | 14,187 | 77.8% | 94 min | 1.02% | B |
| American Airlines | 7,927 | 77.5% | 122 min | 2.35% | B |
| Republic Airways | 873 | 74.8% | 79 min | 4.12% | C− |
| Spirit Airlines | 4,114 | 74.5% | 73 min | 3.23% | C− |
| Frontier Airlines | 5,339 | 70.9% | 86 min | 2.38% | C |
| PSA Airlines | 566 | 68.1% | 123 min | 6.89% | C− |
| JetBlue Airways | 835 | 50.5% | 103 min | 4.79% | F− |
PSA Airlines cancels 6.9% of what it schedules here, the highest in the table. A cancelled flight never appears in an on-time rate, so read that column alongside the punctuality one rather than after it.
Route by route
Where Delta Air Lines flies from IAH
Delta Air Lines operates 7 routes out of IAH with enough volume to report. Route records inside one carrier at one airport still spread widely, because a short shuttle and a transcontinental have very different exposure to a late inbound.
| Route | Flights | On time | Avg delay | Cancelled | Grade |
|---|---|---|---|---|---|
| IAH to ATL · Atlanta | 2,543 | 80.4% | 70 min | 2.04% | B |
| IAH to LGA · New York | 1,347 | 77.5% | 95 min | 4.75% | B− |
| IAH to DTW · Detroit | 1,327 | 82.4% | 72 min | 0.68% | B+ |
| IAH to MSP · Minneapolis | 1,278 | 79.1% | 100 min | 1.10% | B |
| IAH to SLC · Salt Lake City | 1,016 | 83.3% | 90 min | 0.39% | B+ |
| IAH to LAX · Los Angeles | 648 | 87.7% | 70 min | 0.93% | A+ |
| IAH to JFK · New Yorkthin sample | 269 | 78.9% | 86 min | 4.09% | B− |
Flight by flight
Delta Air Lines flight numbers from IAH
11 Delta Air Lines flight numbers leaving IAH flew their main route often enough to have a record of their own. Grouped by destination.
Departure window
Best time of day for this operation
Departure time matters more here than the choice of carrier. The gap between the best and worst window is 17 points, against 31 points between the best and worst carrier.
- 5am–8am2,533 flights89.3%
- 8am–11am863 flights82.0%
- 11am–2pm1,568 flights81.1%
- 2pm–5pm1,817 flights76.3%
- 5pm–8pm1,586 flights72.6%
- 8pm–5am62 flights75.4%
Scale runs 65% to 95%.
Book the early departure. Flights leaving between 5am–8am arrive on time 89.3% of the time, against 72.6% for the evening window. That is 17 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 2,533 flights scheduled in it.
Across the year
Seasonal pattern
December is the weak month at 73.4% on time, against 91.9% 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. May was the busiest month here, with 767 flights.
Delay causes
What holds this operation up
- 44%Carrier
- 35%Late-arriving aircraft
- 18%National Airspace System
- 3%Extreme weather
- 0%Security
35% of delay minutes trace back to a late-arriving aircraft, meaning the plane was already behind before it got here. Across 130,000 reported delay minutes here, that single category outweighs weather by 11 to one. The split is drawn from 129,735 reported delay minutes.
Cancellations sit at 1.90% against a national 1.89%, which is ordinary. Diversions add another 0.32%.
7.1% of arrivals land an hour or more late, close to the national 8.3%, so a 60 to 75 minute layover is reasonable here while anything under 45 minutes is a bet. Most delays on this route last an hour and a half, which a normal layover absorbs.
The sample behind these figures is 8,429 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.
Put together: the calendar is the biggest lever here, not the carrier or the hour. September runs 91.9% on time and December 73.4%, a swing of 19 points. If the dates move at all, move them out of December before you think about anything else. 8,242 completed flights over 12 months sit behind that.
Common questions
Delta Air Lines at IAH
How often is Delta Air Lines at IAH delayed?
About one flight in five arrives at least 15 minutes late, which is the Department of Transportation's definition of a delayed arrival. That works out to 19.0% of the 8,429 flights in this analysis, against 22.7% nationally. Delayed flights are late by an hour and a half on average.
Which airline is most reliable on Delta Air Lines at IAH?
Delta Air Lines leads at 81.0% on time across 8,429 flights. JetBlue Airways is at the other end on 50.5%, a gap of 31 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 Delta Air Lines at IAH?
The 5am–8am departure window is the strongest at 89.3% on time. The 5pm–8pm window is the weakest at 72.6%, 17 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 December delays on Delta Air Lines at IAH?
December is the weakest month at 73.4% on time, compared with 91.9% in September. 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.
Related
Where to go next
Source: US DOT Bureau of Transportation Statistics, on-time performance data, September 2025 to August 2026. Last updated ; recomputed monthly. How this data is collected.