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Flight Reliability

UA 4231 · United Airlines

This number covered several routes in this period.

One number, several routes.

Airlines reuse flight numbers, and UA 4231 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
10 min
Average arrival delay
1.7%
Cancelled
11 min early
Median arrival delay

Based on 302 historical flights. Data through May 2026.

The breakdown

On-time by weekday
  • Mon71%(45 flights)
  • Tue81%(43 flights)
  • Wed80%(39 flights)
  • Thu89%(45 flights)
  • Fri78%(45 flights)
  • Sat89%(36 flights)
  • Sun83%(42 flights)
On-time by departure window
  • 6–9 AM87%(123 flights)
  • 12–3 PM73%(30 flights)
  • 3–6 PM78%(120 flights)
  • 6–9 PM81%(21 flights)
  • 9 PM–12 AM—(1 flights)
On-time trend by month
83%
May

Jun 68% → May 83% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
June 202568%25
July 202575%20
August 202590%19
October 202583%29
November 202568%19
December 202579%28
January 202693%30
February 202682%27
March 202687%31
April 202687%30
May 202683%30
Departures on time
82%
Diverted
0.7%
Flights flown
295
Months covered
12

Keep nerding

Based on 302 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.