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Flight Reliability

WN 1821 · Southwest Airlines

This number covered several routes in this period.

One number, several routes.

Airlines reuse flight numbers, and WN 1821 moved between routes during this period. Numbers below combine all of them, so treat them as background, not a verdict. For a cleaner answer, check the route you are actually flying.

Combined across all its routes

70%
Arrive within 15 minutes
11 min
Average arrival delay
0.3%
Cancelled
1 min early
Median arrival delay

Based on 378 historical flights. Data through May 2026.

The breakdown

On-time by weekday
  • Mon66%(61 flights)
  • Tue81%(42 flights)
  • Wed74%(42 flights)
  • Thu68%(65 flights)
  • Fri71%(69 flights)
  • Sat72%(47 flights)
  • Sun65%(51 flights)
On-time by departure window
  • 6–9 AM92%(74 flights)
  • 9 AM–12 PM83%(46 flights)
  • 12–3 PM59%(91 flights)
  • 3–6 PM54%(52 flights)
  • 6–9 PM67%(67 flights)
  • 9 PM–12 AM68%(47 flights)
On-time trend by month
94%
May

Jun 54% → May 94% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
June 202554%24
July 202563%27
August 202564%22
September 202576%21
October 202577%30
November 202575%28
December 202545%29
January 202687%30
February 202669%55
March 202664%47
April 202676%33
May 202694%31
Departures on time
67%
Diverted
0%
Flights flown
377
Months covered
12

Keep nerding

Based on 378 historical flights, because apparently we checked. Historical flight data: U.S. Bureau of Transportation Statistics, June 2025 – May 2026. Data through May 2026. How we calculate this.