Route Reliability

Route reliability

Denver (DEN) to Washington (IAD): which airline is most on time?

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

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

Denver, COWashington, VA

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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

DEN to IAD

Denver, CO to Washington, VA

On time
81.3%vs 75.6% U.S. average Better than average
Cancelled
0.6%vs 1.9% U.S. average Better than average
60+ min late
5.6%vs 8.1% U.S. average Better than average
Scheduled flights
3,385in 12 months2 airlines
Most reliable airline
United Airlines84.4% on time · 2,790 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 DEN to IAD, 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 84.4% 0.5% 5.2% 66 min 0.0% 2,790
2. Southwest Airlines 67.1% 1.0% 7.6% 47 min 0.0% 595

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 Denver (DEN) to Washington (IAD): 84.4% of its 2,790 scheduled flights arrived within 15 minutes of schedule, compared with 67.1% for Southwest Airlines.
  • 0.6% of flights on this route were cancelled (about 1 in 167), 1.3 points lower than the U.S. average of 1.9%.
  • 5.6% of flights, about 1 in 18, arrived an hour or more late. When a flight was late (15+ minutes), the average arrival delay was 60 min.
  • Overall, 81.3% of flights on this route arrived on time, 5.7 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 July the least reliable (67.9%).
  • Cancellations peaked in January, when 7.0% of flights were cancelled.
  • Flights scheduled to depart 6 am to 7 am were the most punctual (93.5% on time); flights scheduled to depart 7 pm to 8 pm were the least (48.4%).
  • In the other direction, Washington (IAD) to Denver (DEN), 82.1% of flights were on time and 0.6% were cancelled. Compare airlines IAD to DEN.

Best and worst months to fly DEN to IAD

Jan 74.3%
Feb 82.3%
Mar 78.4%
Apr 81.8%
May 73.9%
Jun 72.3%
Jul 67.9%
Aug 73.5%
Sep 79.8%
Oct 85.5%
Nov 84.9%
Dec 84.2%
Share of scheduled flights on time 12-month average 81.3%
All airlines combined, by calendar month, September 2023 to August 2026 (3 years pooled). Scale starts at zero.
Show as table
PeriodOn timeFlights
January 74.3% 754
February 82.3% 688
March 78.4% 846
April 81.8% 845
May 73.9% 928
June 72.3% 878
July 67.9% 929
August 73.5% 888
September 79.8% 826
October 85.5% 815
November 84.9% 757
December 84.2% 815
Best and worst calendar month by airline, September 2023 to August 2026.
AirlineBest monthWorst month
United Airlines October (89.5%) July (69.3%)
Southwest Airlines November (81.8%) June (57.2%)

Month by month, last 12 months

Sep 79.1%
Oct 85.2%
Nov 86.9%
Dec 84.7%
Jan 85.7%
Feb 84.4%
Mar 75.0%
Apr 88.3%
May 80.4%
Jun 80.2%
Jul 69.9%
Aug 75.5%
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 79.1% 292
Oct 2025 85.2% 283
Nov 2025 86.9% 275
Dec 2025 84.7% 307
Jan 2026 85.7% 279
Feb 2026 84.4% 257
Mar 2026 75.0% 300
Apr 2026 88.3% 291
May 2026 80.4% 316
Jun 2026 80.2% 262
Jul 2026 69.9% 266
Aug 2026 75.5% 257

Best and worst departure times

<6a Insufficient sample
6a 93.5%
7a 93.5%
8a 92.3%
9a 82.6%
10a 78.0%
11a 82.1%
12p 72.7%
1p 84.9%
2p 81.7%
3p 81.9%
4p 83.2%
5p 72.4%
6p 59.4%
7p 48.4%
8p Insufficient sample
11p 93.3%
Share of scheduled flights on time
By scheduled local departure hour at DEN, 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 Insufficient sample 2
Departing 6 am to 7 am 93.5% 199
Departing 7 am to 8 am 93.5% 199
Departing 8 am to 9 am 92.3% 234
Departing 9 am to 10 am 82.6% 69
Departing 10 am to 11 am 78.0% 437
Departing 11 am to noon 82.1% 301
Departing noon to 1 pm 72.7% 121
Departing 1 pm to 2 pm 84.9% 350
Departing 2 pm to 3 pm 81.7% 71
Departing 3 pm to 4 pm 81.9% 270
Departing 4 pm to 5 pm 83.2% 155
Departing 5 pm to 6 pm 72.4% 337
Departing 6 pm to 7 pm 59.4% 170
Departing 7 pm to 8 pm 48.4% 128
Departing 8 pm to 9 pm Insufficient sample 1
Departing 11 pm to midnight 93.3% 341
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 Denver, CO (DEN) to Washington, VA (IAD), 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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