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Flight Reliability

UA 421 · United Airlines

This number covered several routes in this period.

One number, several routes.

Airlines reuse flight numbers, and UA 421 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

74%
Arrive within 15 minutes
16 min
Average arrival delay
0.2%
Cancelled
3 min early
Median arrival delay

Based on 444 historical flights. Data through May 2026.

The breakdown

On-time by weekday
  • Mon75%(64 flights)
  • Tue77%(61 flights)
  • Wed76%(62 flights)
  • Thu67%(63 flights)
  • Fri73%(64 flights)
  • Sat83%(64 flights)
  • Sun66%(65 flights)
On-time by departure window
  • 9 AM–12 PM88%(186 flights)
  • 3–6 PM63%(238 flights)
  • 6–9 PM74%(19 flights)
On-time trend by month
94%
May

Jun 27% → May 94% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
June 202527%30
July 202526%31
August 202545%31
September 202573%30
October 2025100%37
November 202588%59
December 202574%46
January 202681%36
February 202682%27
March 202678%55
April 202697%30
May 202694%31
Departures on time
79%
Diverted
0%
Flights flown
443
Months covered
12

Keep nerding

Based on 444 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.