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Flight Reliability

UA 4639 · United Airlines

This number covered several routes in this period.

One number, several routes.

Airlines reuse flight numbers, and UA 4639 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

65%
Arrive within 15 minutes
29 min
Average arrival delay
1.4%
Cancelled
3 min early
Median arrival delay

Based on 365 historical flights. Data through May 2026.

The breakdown

On-time by weekday
  • Mon44%(52 flights)
  • Tue73%(52 flights)
  • Wed74%(50 flights)
  • Thu74%(50 flights)
  • Fri64%(52 flights)
  • Sat70%(50 flights)
  • Sun59%(53 flights)
On-time by departure window
  • 6–9 AM73%(168 flights)
  • 9 AM–12 PM52%(64 flights)
  • 12–3 PM60%(72 flights)
  • 3–6 PM—(2 flights)
  • 6–9 PM67%(52 flights)
  • 9 PM–12 AM—(1 flights)
On-time trend by month
29%
May

Jun 56% → May 29% on time

On-time arrival percentage by month
MonthOn-time percentageFlights
June 202556%27
July 202570%30
August 202571%31
September 202576%29
October 202574%31
November 202580%30
December 202555%31
January 202677%30
February 202664%28
March 202687%31
April 202643%30
May 202629%31
Departures on time
71%
Diverted
0.3%
Flights flown
359
Months covered
12

Keep nerding

Based on 365 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.