Route Reliability

Route reliability

Atlanta (ATL) to Denver (DEN): which airline is most on time?

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

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

Atlanta, GADenver, 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

ATL to DEN

Atlanta, GA to Denver, CO

On time
76.9%vs 75.6% U.S. average About average
Cancelled
1.1%vs 1.9% U.S. average Better than average
60+ min late
7.2%vs 8.1% U.S. average About average
Scheduled flights
5,594in 12 months4 airlines
Most reliable airline
United Airlines85.0% on time · 923 flights

On time about as often as 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 ATL 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 85.0% 0.4% 6.5% 83 min 0.5% 923
2. Delta Air Lines 77.9% 1.2% 6.1% 52 min 0.2% 2,807
3. Southwest Airlines 72.3% 1.2% 8.8% 57 min 0.5% 1,071
4. Frontier Airlines 70.0% 1.4% 10.0% 79 min 0.3% 793

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 Atlanta (ATL) to Denver (DEN): 85.0% of its 923 scheduled flights arrived within 15 minutes of schedule, compared with 70.0% for Frontier Airlines.
  • 1.1% of flights on this route were cancelled (about 1 in 91), 0.8 points lower than the U.S. average of 1.9%.
  • 7.2% of flights, about 1 in 14, arrived an hour or more late. When a flight was late (15+ minutes), the average arrival delay was 61 min.
  • Overall, 76.9% of flights on this route arrived on time, 1.3 points higher than the U.S. average of 75.6%.
  • Over the last 3 years, November was the most reliable month on this route (85.8% on time) and May the least reliable (67.2%).
  • Cancellations peaked in January, when 3.1% of flights were cancelled.
  • Flights scheduled to depart 6 am to 7 am were the most punctual (90.3% on time); flights scheduled to depart 6 pm to 7 pm were the least (61.3%).
  • In the other direction, Denver (DEN) to Atlanta (ATL), 77.4% of flights were on time and 0.9% were cancelled. Compare airlines DEN to ATL.

Best and worst months to fly ATL to DEN

Jan 77.7%
Feb 79.9%
Mar 81.0%
Apr 73.7%
May 67.2%
Jun 70.9%
Jul 68.3%
Aug 73.1%
Sep 81.4%
Oct 83.9%
Nov 85.8%
Dec 78.2%
Share of scheduled flights on time 12-month average 76.9%
All airlines combined, by calendar month, September 2023 to August 2026 (3 years pooled). Scale starts at zero.
Show as table
PeriodOn timeFlights
January 77.7% 1,339
February 79.9% 1,253
March 81.0% 1,414
April 73.7% 1,425
May 67.2% 1,522
June 70.9% 1,565
July 68.3% 1,610
August 73.1% 1,507
September 81.4% 1,444
October 83.9% 1,498
November 85.8% 1,427
December 78.2% 1,480
Best and worst calendar month by airline, September 2023 to August 2026.
AirlineBest monthWorst month
United Airlines October (90.2%) May (76.5%)
Delta Air Lines November (89.5%) July (67.5%)
Southwest Airlines November (86.1%) May (62.8%)
Frontier Airlines October (70.6%) June (53.9%)

Month by month, last 12 months

Sep 81.1%
Oct 78.1%
Nov 85.5%
Dec 67.0%
Jan 81.8%
Feb 79.8%
Mar 75.8%
Apr 79.9%
May 77.0%
Jun 76.5%
Jul 74.6%
Aug 67.4%
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 81.1% 450
Oct 2025 78.1% 474
Nov 2025 85.5% 449
Dec 2025 67.0% 457
Jan 2026 81.8% 429
Feb 2026 79.8% 410
Mar 2026 75.8% 459
Apr 2026 79.9% 442
May 2026 77.0% 483
Jun 2026 76.5% 515
Jul 2026 74.6% 532
Aug 2026 67.4% 494

Best and worst departure times

6a 90.3%
7a 85.0%
8a 86.5%
9a 88.6%
10a 81.4%
11a 89.7%
12p 82.8%
1p 76.0%
2p 75.5%
3p 73.3%
4p 71.1%
5p 50.0%
6p 61.3%
7p 63.6%
8p 64.4%
9p 78.7%
10p 72.5%
11p 66.7%
Share of scheduled flights on time
By scheduled local departure hour at ATL, September 2025 to August 2026. Hours with no scheduled flights are omitted. Scale starts at zero.
Show as table
PeriodOn timeFlights
Departing 6 am to 7 am 90.3% 196
Departing 7 am to 8 am 85.0% 505
Departing 8 am to 9 am 86.5% 438
Departing 9 am to 10 am 88.6% 297
Departing 10 am to 11 am 81.4% 371
Departing 11 am to noon 89.7% 358
Departing noon to 1 pm 82.8% 506
Departing 1 pm to 2 pm 76.0% 337
Departing 2 pm to 3 pm 75.5% 204
Departing 3 pm to 4 pm 73.3% 90
Departing 4 pm to 5 pm 71.1% 629
Departing 5 pm to 6 pm 50.0% 78
Departing 6 pm to 7 pm 61.3% 476
Departing 7 pm to 8 pm 63.6% 239
Departing 8 pm to 9 pm 64.4% 430
Departing 9 pm to 10 pm 78.7% 188
Departing 10 pm to 11 pm 72.5% 189
Departing 11 pm to midnight 66.7% 63
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 Atlanta, GA (ATL) 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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