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Flight Reliability

UA 5121 · United Airlines

This number covered several routes in this period.

One number, several routes.

Airlines reuse flight numbers, and UA 5121 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
16 min
Average arrival delay
4.0%
Cancelled
9 min early
Median arrival delay

Based on 552 historical flights. Data through May 2026.

The breakdown

On-time by weekday
  • Mon87%(82 flights)
  • Tue86%(50 flights)
  • Wed81%(82 flights)
  • Thu78%(88 flights)
  • Fri77%(87 flights)
  • Sat76%(53 flights)
  • Sun81%(84 flights)
On-time by departure window
  • 3–6 AM82%(334 flights)
  • 6–9 AM79%(163 flights)
  • 9 AM–12 PM76%(29 flights)
On-time trend by month
90%
May

Jun 83% → May 90% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
June 202583%47
July 202594%31
August 202584%51
September 202592%50
October 202587%54
November 202589%47
December 202564%39
January 202665%46
February 202674%34
March 202671%41
April 202672%47
May 202690%39
Departures on time
84%
Diverted
0.7%
Flights flown
526
Months covered
12

Keep nerding

Based on 552 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.