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Route on-time record

IAD to DEN: most on-time flights and the best time to fly

Dulles (Washington Dulles International Airport) to Denver (Denver International Airport). 3,624 nonstop flights in Jun 2025 to May 2026, 81% arrived within 15 minutes and 0.7% were cancelled. The most reliable flight number was United 1865 at 9:55 AM.

Flying on a specific date? We’ll adjust for the month, the weekday and the forecast.

IAD → DEN

Dulles to Denver: 3,624 nonstop flights a year

On time (12 months)

81%

Cancelled

0.7%

avg delay 14 min

Best time to leave

9 AM to noon

91% on time vs 62% 6 to 9 PM

Most reliable airline

United

82% chance on time

Check IAD to DEN fares

Fares open on our travel partner (Aviasales). Pick the flight number you chose here.

Most reliable nonstop flights

Ranked by the chance the flight operates and arrives within 15 minutes of schedule, from Jun 2025 to May 2026 records.

  1. #1 · United 1865

    9:55 AM → 12:00 PM4h 05m nonstop

    Local times, typical schedule. Last flown 2026-05-31.

    93%

    chance on time

    On time (history)
    95%
    Cancelled
    0.0%
    Avg arrival delay
    4 min
    • Arrived on time 95% of the time (86 flights, Jun 2025 to May 2026).
    • Never cancelled in 88 scheduled flights.
    • Leaves in this route's most on-time window (9 AM to noon: 91% on time; 6 to 9 PM: 62%).
    • Departs outside IAD's trouble window (1 PM to 7 PM, when 75% of its 63 ground stops and delay programs started).

    Moderate track record · 86 flights

    Find United 1865 fares Opens this date on Aviasales

  2. #2 · United 2035

    6:30 AM → 8:22 AM3h 52m nonstop

    Local times, typical schedule. Last flown 2026-05-31.

    91%

    chance on time

    On time (history)
    100%
    Cancelled
    0.0%
    Avg arrival delay
    0 min
    • Arrived on time 100% of the time (11 flights, Jun 2025 to May 2026).
    • Departs outside IAD's trouble window (1 PM to 7 PM, when 75% of its 63 ground stops and delay programs started).
    • Short track record (11 flights), so its score leans on the airline's record at this hour.

    Limited track record · 11 flights

    Find United 2035 fares Opens this date on Aviasales

  3. #3 · United 1587

    12:43 PM → 2:48 PM4h 05m nonstop

    Local times, typical schedule. Last flown 2026-05-31.

    91%

    chance on time

    On time (history)
    92%
    Cancelled
    0.3%
    Avg arrival delay
    8 min
    • Arrived on time 92% of the time (288 flights, Jun 2025 to May 2026).
    • Departs outside IAD's trouble window (1 PM to 7 PM, when 75% of its 63 ground stops and delay programs started).
    • Lands inside DEN's trouble window: 79% of its 174 ground stops and delay programs started between 2 PM and 8 PM.

    Strong track record · 288 flights

    Find United 1587 fares Opens this date on Aviasales

  4. #4 · United 644

    8:25 AM → 10:28 AM4h 03m nonstop

    Local times, typical schedule. Last flown 2026-05-20. Same departure also flew as United 1256; its record covers all of them.

    88%

    chance on time

    On time (history)
    92%
    Cancelled
    0.0%
    Avg arrival delay
    4 min
    • Arrived on time 92% of the time (52 flights, Jun 2025 to May 2026).
    • Never cancelled in 53 scheduled flights.
    • Departs outside IAD's trouble window (1 PM to 7 PM, when 75% of its 63 ground stops and delay programs started).
    • Short track record (52 flights), so its score leans on the airline's record at this hour.

    Limited track record · 52 flights

    Find United 644 fares Opens this date on Aviasales

  5. #5 · United 2768

    8:15 AM → 10:10 AM3h 55m nonstop

    Local times, typical schedule. Last flown 2026-05-31. Same departure also flew as United 2357; its record covers all of them.

    87%

    chance on time

    On time (history)
    91%
    Cancelled
    0.0%
    Avg arrival delay
    4 min
    • Arrived on time 91% of the time (35 flights, Jun 2025 to May 2026).
    • Never cancelled in 35 scheduled flights.
    • Departs outside IAD's trouble window (1 PM to 7 PM, when 75% of its 63 ground stops and delay programs started).
    • Short track record (35 flights), so its score leans on the airline's record at this hour.

    Limited track record · 35 flights

    Find United 2768 fares Opens this date on Aviasales

  6. #6 · United 1126

    2:37 PM → 4:45 PM4h 08m nonstop

    Local times, typical schedule. Last flown 2026-05-31.

    85%

    chance on time

    On time (history)
    90%
    Cancelled
    0.0%
    Avg arrival delay
    4 min
    • Arrived on time 90% of the time (31 flights, Jun 2025 to May 2026).
    • Never cancelled in 32 scheduled flights.
    • Departs inside IAD's trouble window: 75% of its 63 ground stops and delay programs started between 1 PM and 7 PM.
    • Lands inside DEN's trouble window: 79% of its 174 ground stops and delay programs started between 2 PM and 8 PM.

    Limited track record · 31 flights

    Find United 1126 fares Opens this date on Aviasales

  7. #7 · Southwest 2439

    5:55 AM → 7:45 AM3h 50m nonstop

    Local times, typical schedule. Last flown 2026-05-31. Same departure also flew as Southwest 3339; its record covers all of them.

    85%

    chance on time

    On time (history)
    89%
    Cancelled
    1.1%
    Avg arrival delay
    5 min
    • Arrived on time 89% of the time (87 flights, Jun 2025 to May 2026).
    • Departs outside IAD's trouble window (1 PM to 7 PM, when 75% of its 63 ground stops and delay programs started).

    Moderate track record · 87 flights

    Find Southwest 2439 fares Opens this date on Aviasales

  8. #8 · United 495

    10:35 PM → 12:44 AM4h 09m nonstop

    Local times, typical schedule. Last flown 2026-05-31.

    82%

    chance on time

    On time (history)
    82%
    Cancelled
    0.6%
    Avg arrival delay
    14 min
    • Arrived on time 82% of the time (308 flights, Jun 2025 to May 2026).
    • Departs outside IAD's trouble window (1 PM to 7 PM, when 75% of its 63 ground stops and delay programs started).

    Strong track record · 308 flights

    Find United 495 fares Opens this date on Aviasales

  9. #9 · United 395

    4:00 PM → 6:10 PM4h 10m nonstop

    Local times, typical schedule. Last flown 2026-05-31.

    82%

    chance on time

    On time (history)
    85%
    Cancelled
    0.0%
    Avg arrival delay
    11 min
    • Arrived on time 85% of the time (88 flights, Jun 2025 to May 2026).
    • Never cancelled in 88 scheduled flights.
    • Departs inside IAD's trouble window: 75% of its 63 ground stops and delay programs started between 1 PM and 7 PM.
    • Lands inside DEN's trouble window: 79% of its 174 ground stops and delay programs started between 2 PM and 8 PM.

    Moderate track record · 88 flights

    Find United 395 fares Opens this date on Aviasales

  10. #10 · United 431

    2:21 PM → 4:28 PM4h 07m nonstop

    Local times, typical schedule. Last flown 2026-04-29.

    82%

    chance on time

    On time (history)
    84%
    Cancelled
    0.0%
    Avg arrival delay
    10 min
    • Arrived on time 84% of the time (55 flights, Jun 2025 to May 2026).
    • Never cancelled in 56 scheduled flights.
    • Departs inside IAD's trouble window: 75% of its 63 ground stops and delay programs started between 1 PM and 7 PM.
    • Lands inside DEN's trouble window: 79% of its 174 ground stops and delay programs started between 2 PM and 8 PM.

    Limited track record · 55 flights

    Find United 431 fares Opens this date on Aviasales

Airlines on this route

Season-adjusted chance of operating and arriving on time.

  • United Airlines82%

    2,787 flights · 83% on time as flown · 0.5% cancel

  • Southwest Airlines75%

    837 flights · 75% on time as flown · 1.2% cancel

On time by departure time

All airlines, scheduled local departure, Jun 2025 to May 2026.

  • Before 9 AM89%

    804 flights · avg delay 9 min

  • 9 AM to noon91%

    394 flights · avg delay 6 min

  • Noon to 3 PM86%

    833 flights · avg delay 11 min

  • 3 to 6 PM72%

    885 flights · avg delay 20 min

  • 6 to 9 PM62%

    367 flights · avg delay 23 min

  • After 9 PM83%

    341 flights · avg delay 13 min

On time by month

All airlines, Jun 2023 to May 2026. Several years per month, so one stormy season doesn't define a month. Travel-month estimates use this seasonal pattern.

J
82
F
81
M
86
A
82
M
77
J
73
J
70
A
77
S
86
O
88
N
90
D
85

What delays this route

  • Late-arriving aircraft35%
  • Air traffic control and airport volume30%
  • Airline (crew, maintenance, boarding)26%
  • Severe weather9%

Share of delay minutes by the cause airlines report to the US DOT.

Historical odds, not a guarantee. Built from the US DOT Bureau of Transportation Statistics on-time reports (Jun 2025 to May 2026), FAA ground stop and delay program advisories, and 20 years of airport weather observations. Covers US airlines that report to the DOT; schedules are flights operated recently, so confirm times when you book. ATIS Alerts is not affiliated with any airline. Fares are what Aviasales travelers saw in recent searches (USD, one way, 1 adult), not live quotes; the partner site shows the current price. Fare links go to our travel partner and may earn us a commission at no cost to you. Affiliate disclosure

IAD to DEN questions

What time of day is best to fly IAD to DEN?
9 AM to noon: 91% of flights arrived on time, against 62% for departures 6 to 9 PM.
Which airline is most on time from IAD to DEN?
United, with a season-adjusted 82% chance of operating and arriving on time over 2,787 flights. The adjustment compares each airline with what the route did in the months it flew, so a carrier that skipped a stormy month gets no free credit.
What is the worst month for delays on IAD to DEN?
July (70% on time); the best was November (90%), averaged over Jun 2023 to May 2026.
Is this a prediction for my flight?
No. These are historical odds from the US DOT on-time reports, FAA advisories and airport weather records. Check your flight status and the FAA delay board on the day you fly.

More routes from IAD

Live status: FAA delays and ground stops