Route Reliability

Route reliability

Houston (IAH) to Denver (DEN): which airline is most on time?

On-time arrivals, cancellations and long delays for every airline that reported nonstop flights from Houston, TX (IAH) to Denver, CO (DEN), September 2025 to August 2026.

Historical performance Official DOT data through August 2026 · Not live flight status

Houston, TXDenver, CO

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Three-letter airport codes, nonstop U.S. domestic flights. One direction at a time.

Route at a glance · September 2025 to August 2026

IAH to DEN

Houston, TX to Denver, CO

On time
82.5%vs 75.6% U.S. average Better than average
Cancelled
0.4%vs 1.9% U.S. average Better than average
60+ min late
6.2%vs 8.1% U.S. average Better than average
Scheduled flights
4,728in 12 months2 airlines
Most reliable airline
United Airlines83.2% on time · 3,894 flights

On time more often than the U.S. average, with fewer cancellations.

Compared with all U.S. flights, September 2025 to August 2026. “About average” means within 1.5 points for on time, 0.3 for cancelled and 1 for 60+ minutes late.

Airlines on this route

Ranked by on-time arrival

Airlines from IAH to DEN, September 2025 to August 2026. Rates are shares of all scheduled flights.
Airline On time Cancelled 60+ min late Avg delay when late Diverted Flights
1. United Airlines Most reliable 83.2% 0.2% 5.9% 67 min 0.2% 3,894
2. Frontier Airlines 79.1% 1.2% 7.3% 75 min 0.1% 834

On time = arrived within 15 minutes of schedule. Avg delay when late = average arrival delay of flights 15+ minutes late. "Most reliable" needs at least 300 flights in 12 months. Tap a heading to sort.

What this means

United Airlines has the strongest record on this route.

  • United Airlines had the best on-time record from Houston (IAH) to Denver (DEN): 83.2% of its 3,894 scheduled flights arrived within 15 minutes of schedule, compared with 79.1% for Frontier Airlines.
  • 0.4% of flights on this route were cancelled, 1.5 points lower than the U.S. average of 1.9%.
  • 6.2% of flights, about 1 in 16, arrived an hour or more late. When a flight was late (15+ minutes), the average arrival delay was 69 min.
  • Overall, 82.5% of flights on this route arrived on time, 6.9 points higher than the U.S. average of 75.6%.
  • Over the last 3 years, October was the most reliable month on this route (85.5% on time) and June the least reliable (69.4%).
  • Cancellations peaked in January, when 3.8% of flights were cancelled.
  • Flights scheduled to depart before 6 am were the most punctual (96.9% on time); flights scheduled to depart 6 pm to 7 pm were the least (64.6%).
  • In the other direction, Denver (DEN) to Houston (IAH), 79.3% of flights were on time and 0.3% were cancelled. Compare airlines DEN to IAH.

Best and worst months to fly IAH to DEN

Jan 75.6%
Feb 83.7%
Mar 81.9%
Apr 81.8%
May 70.3%
Jun 69.4%
Jul 71.3%
Aug 78.7%
Sep 83.5%
Oct 85.5%
Nov 85.0%
Dec 83.7%
Share of scheduled flights on time 12-month average 82.5%
All airlines combined, by calendar month, September 2023 to August 2026 (3 years pooled). Scale starts at zero.
Show as table
PeriodOn timeFlights
January 75.6% 1,173
February 83.7% 1,065
March 81.9% 1,231
April 81.8% 1,157
May 70.3% 1,254
June 69.4% 1,276
July 71.3% 1,313
August 78.7% 1,234
September 83.5% 1,216
October 85.5% 1,211
November 85.0% 1,127
December 83.7% 1,193
Best and worst calendar month by airline, September 2023 to August 2026.
AirlineBest monthWorst month
United Airlines October (86.5%) June (71.0%)
Frontier Airlines September (83.1%) June (63.2%)

Month by month, last 12 months

Sep 81.7%
Oct 82.8%
Nov 82.9%
Dec 84.4%
Jan 87.0%
Feb 86.5%
Mar 81.0%
Apr 87.8%
May 83.0%
Jun 71.0%
Jul 80.0%
Aug 83.9%
Share of scheduled flights on time U.S. average 75.6%
All airlines combined, September 2025 to August 2026. Scale starts at zero.
Show as table
PeriodOn timeFlights
Sep 2025 81.7% 383
Oct 2025 82.8% 396
Nov 2025 82.9% 357
Dec 2025 84.4% 390
Jan 2026 87.0% 385
Feb 2026 86.5% 347
Mar 2026 81.0% 406
Apr 2026 87.8% 361
May 2026 83.0% 412
Jun 2026 71.0% 431
Jul 2026 80.0% 444
Aug 2026 83.9% 416

Best and worst departure times

<6a 96.9%
6a 89.9%
7a 87.9%
8a 92.3%
9a 84.1%
10a 87.9%
11a 82.8%
12p 88.9%
1p Insufficient sample
2p 78.9%
3p 70.2%
4p 70.1%
5p Insufficient sample
6p 64.6%
7p Insufficient sample
8p 78.9%
9p 85.3%
10p 82.4%
11p Insufficient sample
Share of scheduled flights on time
By scheduled local departure hour at IAH, September 2025 to August 2026. Hours with no scheduled flights are omitted. Scale starts at zero.
Show as table
PeriodOn timeFlights
Departing before 6 am 96.9% 195
Departing 6 am to 7 am 89.9% 484
Departing 7 am to 8 am 87.9% 321
Departing 8 am to 9 am 92.3% 378
Departing 9 am to 10 am 84.1% 239
Departing 10 am to 11 am 87.9% 381
Departing 11 am to noon 82.8% 239
Departing noon to 1 pm 88.9% 370
Departing 1 pm to 2 pm Insufficient sample 3
Departing 2 pm to 3 pm 78.9% 261
Departing 3 pm to 4 pm 70.2% 131
Departing 4 pm to 5 pm 70.1% 395
Departing 5 pm to 6 pm Insufficient sample 32
Departing 6 pm to 7 pm 64.6% 432
Departing 7 pm to 8 pm Insufficient sample 12
Departing 8 pm to 9 pm 78.9% 383
Departing 9 pm to 10 pm 85.3% 129
Departing 10 pm to 11 pm 82.4% 341
Departing 11 pm to midnight Insufficient sample 2
Woman at an airport window watching a plane take off
Photo: Depositphotos (licensed stock, illustrative only). Credits

Sources & data dates

Source
U.S. DOT Bureau of Transportation Statistics, Reporting Carrier On-Time Performance (1987-present)
Period
September 2025 to August 2026 (12 months); month-of-year patterns September 2023 to August 2026
Data through
August 2026
Processed
2026-11-03
Scope
Nonstop scheduled flights from Houston, TX (IAH) to Denver, CO (DEN), one direction. Airlines that report to the DOT only.
Method
Rates use all scheduled flights as the denominator; cancelled and diverted flights count as not on time. Figures based on fewer than 50 scheduled flights are suppressed. Full methodology.

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