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Flight Reliability

UA 1851 · United Airlines

This number covered several routes in this period.

One number, several routes.

Airlines reuse flight numbers, and UA 1851 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

76%
Arrive within 15 minutes
12 min
Average arrival delay
1.2%
Cancelled
2 min early
Median arrival delay

Based on 518 historical flights. Data through May 2026.

The breakdown

On-time by weekday
  • Mon74%(76 flights)
  • Tue82%(67 flights)
  • Wed89%(71 flights)
  • Thu78%(78 flights)
  • Fri61%(79 flights)
  • Sat80%(64 flights)
  • Sun69%(77 flights)
On-time by departure window
  • 6–9 AM90%(118 flights)
  • 9 AM–12 PM80%(91 flights)
  • 12–3 PM74%(91 flights)
  • 3–6 PM69%(84 flights)
  • 6–9 PM58%(86 flights)
  • 9 PM–12 AM79%(42 flights)
On-time trend by month
49%
May

Jun 88% → May 49% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
June 202588%33
July 202586%58
August 202589%55
September 202586%58
October 202582%51
November 202573%45
December 202569%32
January 202662%55
February 202679%38
March 202661%51
May 202649%35
Departures on time
77%
Diverted
0%
Flights flown
512
Months covered
12

Keep nerding

Based on 518 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.