As of October 20, 2026, the latest Bureau of Transportation Statistics (BTS) month is August 2026. That month, 26.0% of flights by reporting US airlines arrived 15 or more minutes late, and another 2.46% were cancelled or diverted. On October 16, the Transportation Department announced a 2.8% pay deal for air traffic controllers tied to staffing changes, with no estimate of any effect on delays. Delays remain common enough to plan for, and the data show when and why they pile up.
Key takeaways
- In August 2026, the largest single delay code was a late-arriving aircraft (10.16% of all scheduled flights), ahead of the national aviation system (7.45%) and the airline itself (7.29%).
- The "extreme weather" code was only 1.06%, but BTS's broader weather measure put weather behind 36.98% of delayed flights that month.
- In calendar 2025, flights scheduled to leave between 5:00 and 8:59 a.m. arrived 15 or more minutes late 12.0% of the time, against 32.0% for departures between 6:00 and 8:59 p.m. (editorial calculation).
- A minimum connection time has no cushion for a late inbound flight, and the FAA's NAS Status page forecasts delays for later the same day.
What it means for you
- Choosing flight times: morning departures ran late far less often than evening ones.
- Tight connections: the minimum connection time is a floor, not a buffer.
- Winter trips through hubs: January 2026 cancellation rates differed widely by airport.
- Families and travelers with medications: see the TSA section and FAQ.
Why flights run late, by cause
A flight is delayed when it arrives 15 or more minutes late; each delay is split among five causes by the minutes each caused, per the BTS delay causes page. Under the reporting rule (14 CFR 234.4), air carrier delays are within the airline's control. Extreme weather prevents a flight from operating. National aviation system (NAS) delays include non-extreme weather, airport operations, heavy traffic and air traffic control. Late-arriving aircraft means the incoming plane was late.
| Outcome, August 2026 | Share of scheduled flights | Share of all delayed flights* |
|---|---|---|
| On time | 71.53% | n/a |
| Late-arriving aircraft | 10.16% | 39.1% |
| National aviation system (NAS) | 7.45% | 28.6% |
| Air carrier | 7.29% | 28.0% |
| Extreme weather (code only) | 1.06% | 4.1% |
| Security | 0.05% | 0.2% |
| Cancelled | 2.00% | n/a |
| Diverted | 0.46% | n/a |
*Editorial calculation: each cause divided by the five causes' total of 26.01%.
The extreme-weather row understates weather. BTS's weather's share of delayed flights adds NAS delays the FAA attributes to weather and weather's share of late-aircraft delays. On that measure, weather was behind 36.98% of delayed flights in August 2026, and 58.34% of NAS delays. A storm anywhere on your aircraft's route that day can reach your flight.
In BTS's flight-level files for 2025 (about 7.0 million scheduled flights; 22.3% of operated flights arrived 15+ minutes late), an editorial calculation gives 39.2% of delay minutes from late-arriving aircraft, 32.5% from air carrier causes, 21.9% from the NAS, 6.4% from extreme weather and 0.1% from security. Of 2025 cancellations, 61.6% carried the extreme-weather code.
When delays build: hour and season
Delays accumulate through the day
Calendar 2025 operated flights by scheduled local departure time (editorial calculation from BTS files):
| Scheduled departure | Arrived 15+ min late | Late-arriving aircraft, share of delay minutes |
|---|---|---|
| 5:00-8:59 a.m. | 12.0% | 17.0% |
| 9:00-11:59 a.m. | 17.5% | 35.8% |
| 12:00-2:59 p.m. | 23.2% | 40.0% |
| 3:00-5:59 p.m. | 29.7% | 41.9% |
| 6:00-8:59 p.m. | 32.0% | 48.4% |
| 9:00-11:59 p.m. | 27.8% | 45.5% |
Not shown: about 16,800 flights scheduled from midnight to 4:59 a.m. (17.0% late). An evening departure was 2.7 times as likely to arrive late as an early-morning one (32.0% divided by 12.0%). The late-aircraft share rises in step, because a plane that lands late passes the delay to its next flight. Still, 12.0% is about one in eight.
Months and winter hubs
In editorial calculations from BTS flight files, the 2025 monthly late-arrival rate ranged from 16.6% in September to 28.9% in July. January 2026 had 4.71% of scheduled flights cancelled, against 0.51% in September 2025, and 87.6% of January's cancellations carried the extreme-weather code. Among the 15 airports with 10,000 or more scheduled departures that month, cancellation rates ranged from 1.7% at Denver to 11.0% at Charlotte, with Dallas/Fort Worth at 9.9% (editorial calculation). One month is noisy, but winter risk clearly differs by hub.
Connection buffers
A minimum connection time (MCT) is the shortest time needed to move a passenger and bags between connecting flights. Travelport's booking-system documentation looks it up by airport and by connection type (domestic or international on each leg); connections the system builds automatically meet it.
It is a floor, not a forecast. Illustrative example: with a 45-minute MCT and an inbound flight landing 20 minutes late, 25 minutes remain, 20 below the minimum. In 2025, 22.3% of operated flights arrived 15 or more minutes late; on a connection booked at exactly the minimum, each of those, and any smaller delay, would leave less than the minimum. Allow more than the minimum after an evening inbound flight, when changing terminals, or when the second flight is the day's last.
FAA tools and staffing news
Reading the NAS Status map
The FAA's NAS Status page shows current and forecast airport closures, ground stops, ground delay programs, arrival and departure delays and de-icing. It updates every minute, per the FAA's NAS Status user guide (September 2022). Forecast events cover later the same day, so check on the morning of travel, for both airports.
The FAA's airport status help page defines the two key terms:
- Ground stop: flights bound for the airport are held where they are, when demand will exceed its acceptance rate for a short period, to buy time for a longer-term fix, or when the rate has fallen to zero.
- Ground delay program: used when demand is expected to exceed the acceptance rate for a lengthy period, most commonly because of low ceilings and visibility. Inbound flights get controlled departure times and may not leave earlier.
Controller staffing and the 2025 cuts
During what Transportation Secretary Sean Duffy later called the longest government shutdown in the nation's history, the FAA announced on November 6, 2025 a temporary cut in flights at 40 airports, citing staffing triggers and controllers working without pay: 4% from November 7, scheduled to reach 10% by November 14. Carriers chose which flights to cancel; the FAA said they had to issue full refunds but not cover secondary costs.
On November 14, the FAA lowered the required cut from 6% to 3% from 6 a.m. on November 15, as staffing triggers fell from a record 81 on November 8. On November 16, it announced the order would end at 6 a.m. on November 17. In an editorial calculation, 53.7% of November 2025 cancellations carried the NAS code, against 17.8% across 2025.
The October 16, 2026 2.8% pay deal comes with tracking of controller hours, shifts set by forecast workload and reassignments to the worst-staffed facilities; the raise takes effect October 18. It gives no delay forecast, so it is no reason to shorten buffers.
TSA lines, MyTSA and PreCheck
During the partial government shutdown in March 2026, TSA's deputy administrator told a House committee on March 25 that wait times at some major airports had exceeded four hours, with officers there calling out at rates of 40% to 50%, as NPR reported. That was exceptional, but checkpoint time can swing widely.
The MyTSA app gives estimated checkpoint wait times, a "What Can I Bring" tool, live assistance and flight-time updates, according to TSA.
For shorter routine screening, TSA says about 99% of PreCheck passengers wait under 10 minutes and that five years of membership costs $85 or less. New-enrollment prices from its three providers were $79.75 to $85.00 as listed on October 20, 2026.
TSA's medication guidance allows medically necessary liquids in reasonable quantities if you declare them at the checkpoint. A Passenger Support Specialist can help through screening if you ask at least 72 hours ahead. It does not exempt you from screening; wheelchairs are arranged through the airline. Ask your clinician and airline about your own needs.
Frequently asked questions
How does BTS decide a flight was delayed?
A flight counts as delayed when it arrives 15 or more minutes after its scheduled time, per the BTS delay causes page. Under 14 CFR 234.4, airlines report each cause that contributed 5 minutes or more. A 10-minute-late arrival does not appear in the cause figures.
Are the delay cause categories changing?
Yes. A DOT final rule effective October 19, 2026 moves ten event types out of the Air Carrier code into a new "Section 511(b)" category. They include non-deferrable unscheduled maintenance, removing an unruly passenger and cyberattacks. The August 2026 figures use the old categories, so air carrier shares for flights after the change won't compare directly.
What decides how long a ground delay program lasts?
According to the FAA's help page, it depends on how far demand exceeded the airport's acceptance rate and for how long. Its sample (74-minute maximum, 36-minute average) illustrates the format, not typical values.
What do "possible," "probable" and "expected" mean on NAS Status?
The FAA's user guide labels forecast events by likelihood. Possible means less than a 30% chance of occurring, probable means 30% to 60%, and expected means it will most likely occur.
Can my children use the PreCheck lane?
TSA's PreCheck page says children 17 and under can join an adult in the TSA PreCheck lane for free. The adult needs a Known Traveler Number entered in the airline reservation so PreCheck appears on the boarding pass.
A checklist for travel day
- When booking, pick the earliest departure that fits the trip; the 5:00-8:59 a.m. block was late 12.0% of the time in 2025.
- For connections, choose more than the published minimum, particularly after an evening inbound flight.
- On the morning of travel, check NAS Status for active and forecast events at both airports, and check MyTSA for checkpoint estimates.
- If a ground stop or ground delay program covers your destination, expect a later departure and watch the airline app.
- Liquid medications: declare them at the checkpoint; request TSA help at least 72 hours ahead if needed.
Sources
- Bureau of Transportation Statistics: Airline On-Time Statistics and Delay Causes, national figures for August 2026, and its weather-share pages. Other figures: editorial calculations from BTS monthly reporting-carrier on-time files.
- 14 CFR 234.4: reporting of on-time performance and delay causes; Federal Register, September 3, 2026: delay and cancellation categories under Section 511(b).
- FAA National Airspace System Status and its user guide.
- FAA: ground delay program, ground stop and delay information help.
- FAA, November 6, 2025: temporary 10% reduction in flights at 40 airports; November 14, 2025; November 16, 2025.
- FAA, October 16, 2026: air traffic controller pay increase deal.
- TSA PreCheck, TSA customer service fact sheet (MyTSA), TSA passenger support and TSA medication guidance.
- NPR, March 25, 2026: Travelers are facing the longest TSA wait times in history.
- Travelport: Minimum Connect Time (MCT).
