FlyerIntel Research
The Latest Weekday, by Airline Size
Sunday is the weekday with the lowest on-time rate in every airline size group.
Published October 18, 2026 · Source period July 2023 – July 2026
Summary
5 of the 5 largest airlines landed on time least often on Sunday, against 3 of the 5 smallest on Sunday. Pooled, the largest group’s Sunday rate is 75.9% and the smallest group’s Sunday rate is 73.7%. The pooled worst weekday is Sunday in all three groups.
Key findings
- The largest third of airlines (5) has its pooled worst weekday on Sunday at 75.9% on time and its best on Tuesday at 82.2%.
- The smallest third (5) has its pooled worst weekday on Sunday at 73.7% and its best on Wednesday at 80.8%.
- The median airline’s best weekday beats its worst by 6.3 points in the largest third, 5.1 in the middle and 7.0 in the smallest.
- Of the 15 airlines, 15 have a best and worst weekday more than 2 standard errors apart.
Does the late day move with airline size
Airlines are ranked by scheduled flights over the period and cut into the largest third, the middle third and the smallest third. Within each airline the report finds the weekday on which flights landed on time least often. It then counts how many airlines in each group share the group’s weakest weekday. Size goes together with network shape and route mix, so a difference between groups is not a size effect on its own.
On-time rate by weekday and airline size, pooled
| Weekday | Largest third (5 airlines) | Middle third (5 airlines) | Smallest third (5 airlines) |
|---|---|---|---|
| Monday | 78.3% | 77.6% | 75.3% |
| Tuesday | 82.2% | 81.4% | 80.5% |
| Wednesday | 81.6% | 80.3% | 80.8% |
| Thursday | 77.9% | 77.2% | 76.3% |
| Friday | 77.2% | 76.8% | 75.1% |
| Saturday | 79.8% | 79.3% | 76.8% |
| Sunday | 75.9% | 75.7% | 73.7% |
Each cell adds on-time and completed flights over the group’s airlines before dividing. On time is flights that landed within 15 minutes of schedule over flights that completed, summed over every hour of the weekday. Weekday is the scheduled departure weekday at the flight’s origin. The worst weekday is the one with the lowest rate; spread is the best weekday’s rate less the worst’s.
How many airlines have each weekday as their worst
| Weekday | Largest third | Middle third | Smallest third |
|---|---|---|---|
| Monday | 0 | 0 | 0 |
| Tuesday | 0 | 0 | 0 |
| Wednesday | 0 | 0 | 0 |
| Thursday | 0 | 0 | 0 |
| Friday | 0 | 1 | 2 |
| Saturday | 0 | 0 | 0 |
| Sunday | 5 | 4 | 3 |
Counts add to the number of airlines in each group. Ties go to the earlier weekday.
Each airline’s worst and best weekday
| Airline | Size | Scheduled flights | Worst weekday | On time | Best weekday | On time | Spread, points |
|---|---|---|---|---|---|---|---|
| Southwest Airlines | Largest third | 4,371,639 | Sunday | 74.6% | Tuesday | 82.5% | 7.9 |
| Delta Air Lines | Largest third | 3,146,502 | Sunday | 78.7% | Wednesday | 85.0% | 6.3 |
| American Airlines | Largest third | 3,019,376 | Sunday | 71.5% | Tuesday | 78.4% | 6.9 |
| SkyWest Airlines | Largest third | 2,433,643 | Sunday | 78.4% | Tuesday | 82.8% | 4.5 |
| United Airlines | Largest third | 2,418,979 | Sunday | 77.8% | Tuesday | 82.6% | 4.8 |
| Republic Airways | Middle third | 1,004,281 | Sunday | 80.4% | Tuesday | 84.3% | 3.9 |
| Envoy Air | Middle third | 886,878 | Sunday | 77.6% | Tuesday | 83.2% | 5.6 |
| Alaska Airlines | Middle third | 813,732 | Friday | 76.9% | Tuesday | 81.9% | 5.1 |
| JetBlue | Middle third | 745,492 | Sunday | 67.7% | Tuesday | 77.5% | 9.8 |
| PSA Airlines | Middle third | 717,562 | Sunday | 73.7% | Tuesday | 78.2% | 4.5 |
| Spirit Airlines | Smallest third | 635,598 | Sunday | 71.9% | Wednesday | 80.2% | 8.4 |
| Frontier Airlines | Smallest third | 629,235 | Sunday | 68.7% | Wednesday | 75.7% | 7.0 |
| Allegiant Air | Smallest third | 381,495 | Sunday | 72.9% | Wednesday | 80.6% | 7.7 |
| Endeavor Air | Smallest third | 304,230 | Friday | 82.4% | Wednesday | 86.8% | 4.4 |
| Hawaiian Airlines | Smallest third | 199,679 | Friday | 80.3% | Tuesday | 85.7% | 5.4 |
Sorted from the most scheduled flights to the fewest.
What this does not show
A weekday’s rate mixes routes with hours of the day and with airports, and those differ by airline, so the late day can be an effect of where a carrier flies and not of the carrier. A small airline’s rate on one weekday rests on fewer flights than a large airline’s. The weekday is the day a flight was scheduled to leave, local time at its origin, and the on-time rate is for arrival. Airlines are included with at least 10,000 completed flights over the period and at least 500 on every weekday. Flights with no scheduled departure time are not in the source table.
Pages for what this report covers
Airlines: Southwest Airlines · Delta Air Lines · American Airlines · SkyWest Airlines · United Airlines · Republic Airways
Methodology
Calculated by FlyerIntel from 21,708,321 individual flight records in the US Department of Transportation Bureau of Transportation Statistics Reporting Carrier On-Time Performance dataset, covering July 2023 through July 2026. Following BTS methodology, a flight counts as delayed when it arrives 15 or more minutes after its scheduled arrival time. Cancelled and diverted flights have no arrival time and are excluded from on-time rates rather than counted as late; cancellation rates are reported separately. Full definitions are published at /methodology/. Flights are counted once, under the airline that operated them, from the airline’s weekday-by-hour table added up across the hours of the day. Groups are rank cuts of scheduled flights: the first third of airlines by size, the last third, and the rest. A best and worst weekday are called clearly apart only when a two-proportion z of at least 2 separates them; this guards against naming a tie and is not an interval. Group rates add counts before dividing.
Limitations
The source dataset covers scheduled domestic flights operated by carriers above the DOT reporting threshold; smaller carriers and international flights are not included. Flights sold under a mainline brand but flown by a regional carrier are attributed to the operating carrier, which is how the DOT records them. Past performance describes what has happened and is not a prediction about any individual flight.
Sources
- FlyerIntel analysis — FlyerIntel · source
- Reporting Carrier On-Time Performance — US Department of Transportation, Bureau of Transportation Statistics · source
Full FlyerIntel methodology · Report a problem with this analysis