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Flight Reliability

WN 4221 · Southwest Airlines

This number covered several routes in this period.

One number, several routes.

Airlines reuse flight numbers, and WN 4221 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

81%
Arrive within 15 minutes
5 min
Average arrival delay
1.9%
Cancelled
2 min early
Median arrival delay

Based on 265 historical flights. Data through May 2026.

The breakdown

On-time by weekday
  • Mon79%(43 flights)
  • Tue76%(42 flights)
  • Wed82%(38 flights)
  • Thu81%(36 flights)
  • Fri86%(42 flights)
  • Sat85%(26 flights)
  • Sun82%(33 flights)
On-time by departure window
  • 3–6 AM—(1 flights)
  • 6–9 AM88%(91 flights)
  • 9 AM–12 PM86%(92 flights)
  • 12–3 PM86%(21 flights)
  • 3–6 PM—(5 flights)
  • 6–9 PM56%(16 flights)
  • 9 PM–12 AM62%(34 flights)
On-time trend by month
68%
May

Jun 50% → May 68% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
June 202550%24
July 202569%26
November 202577%30
December 202583%40
January 202697%35
February 202698%42
March 202692%13
April 202682%22
May 202668%25
Departures on time
79%
Diverted
0%
Flights flown
260
Months covered
10

Keep nerding

Based on 265 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.