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Flight Reliability

UA 1231 · United Airlines

This number covered several routes in this period.

One number, several routes.

Airlines reuse flight numbers, and UA 1231 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

79%
Arrive within 15 minutes
13 min
Average arrival delay
1.2%
Cancelled
10 min early
Median arrival delay

Based on 421 historical flights. Data through May 2026.

The breakdown

On-time by weekday
  • Mon79%(65 flights)
  • Tue88%(57 flights)
  • Wed82%(51 flights)
  • Thu69%(55 flights)
  • Fri82%(65 flights)
  • Sat79%(57 flights)
  • Sun76%(66 flights)
On-time by departure window
  • 12–3 AM100%(29 flights)
  • 6–9 AM89%(240 flights)
  • 9 AM–12 PM—(3 flights)
  • 12–3 PM63%(38 flights)
  • 3–6 PM70%(37 flights)
  • 6–9 PM49%(69 flights)
On-time trend by month
94%
May

Jun 77% → May 94% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
June 202577%30
July 202530%23
August 202548%31
September 202572%29
October 202582%27
November 202593%30
December 202586%42
January 202688%43
February 202681%48
March 202685%33
April 202687%45
May 202694%35
Departures on time
82%
Diverted
0%
Flights flown
416
Months covered
12

Keep nerding

Based on 421 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.