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Flight Reliability

UA 4539 · United Airlines

This number covered several routes in this period.

One number, several routes.

Airlines reuse flight numbers, and UA 4539 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
26 min
Average arrival delay
3.1%
Cancelled
5 min early
Median arrival delay

Based on 323 historical flights. Data through May 2026.

The breakdown

On-time by weekday
  • Mon77%(43 flights)
  • Tue83%(46 flights)
  • Wed70%(47 flights)
  • Thu74%(43 flights)
  • Fri72%(43 flights)
  • Sat69%(45 flights)
  • Sun72%(43 flights)
On-time by departure window
  • 6–9 AM81%(158 flights)
  • 9 AM–12 PM—(8 flights)
  • 12–3 PM42%(19 flights)
  • 3–6 PM68%(122 flights)
  • 6–9 PM—(3 flights)
On-time trend by month
86%
May

Jul 58% → May 86% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
July 202558%26
August 202565%31
September 202583%29
October 202581%31
November 202579%29
December 202548%21
January 202668%28
February 202692%26
March 202667%30
April 202693%29
May 202686%22
Departures on time
75%
Diverted
0.9%
Flights flown
310
Months covered
12

Keep nerding

Based on 323 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.